Note: Descriptions are shown in the official language in which they were submitted.
12346- 1
1~71837
The present invention relates in general to novel
zeolite compositions and to the method for their prePara-
tion. More particularly it relates to zeolite compositions
topologically related to prior known zeolites but which
have substantially greater SiO2/A1203 molar ratios than the
heretofore known zeolite species and characterized by containin~,
framework silicon atoms from an extraneous source, and
preferably a very low content of defect sites in the struc-
ture. In general the preparative process involves contactin~
the starting zeolite under controlled conditions with an
aqueous solution of a fluorosilicate salt, preferablv one
which toes not form insoluble salts with aluminum.
The crystal structures of naturally occurring and
as-synthesized zeolitic aluminosilicates are composed of
A104 and SiO4 tetrahedra which are cross-linked by the
sharing of oxygen atoms. The electrovalence of each tetra-
hedron containing an aluminum atom is balanced by associa~ion
with a cation. Most commonly this cation is a metal cation
such a~Na or K but organic species such as quaternary
ammonium ions are also employed in zeolite synthesis and in
some instances appear as cations in the synthesized product
zeolite. In general the metal cations are, to a considerable
extent at least, replaceable with other cations including
H+ and NH4+, In many instances the organic cation species
are too large to pass through the pore system of the zeolite
and hence cannot be directly replaced by ion exchange tech-
niques, Thermal treatments can reduce these organic cations
to H+ or NH4+ cations which can be directly ion-exchan~ed.
Thermal treatment of the H or NH4~ cationic forms of the
zeolites can result in the substantial re~oval of these
cations from their normal association with the A104
tetrahedra thereby creating an electrovalent imbalance in
~,
-- 2 --
12346-l
i~7~83~7
the zeolite structure which must be accompanied by struc-
tural rearrangements to restore the electrovalent balance.
Commonly when the Al04 Setrahedra constitute about 40~/~ or
more of the total framework tetrahedra, the necessary
structural rearrangements cannot be accommodat~d and the
crystal structure colla?ses. In more siliceous zeolites,
the structural integrity is substantially maintained but
the resulting "decationized" form has certain significantly
different properties from its fully cationized precursor.
The relative instability of aluminum in zeolites,
particularly in the non-metallic cationic or the decation-
ized form, is well recognized in theart. For example, in
.S.P. 3,640,681, issued to P.E. Pickert on February 3, 1972,
there is disclosed a process for extracting framework aluminum
from zeolites which involves dehydroxylating a partially
cation deficient form of the zeolite and then contacting
it with acetylacetone or a metal terivative thereof to chelate
and solubilize aluminum atoms. Ethylenediaminetetraacetic
acid has been proposed as an extractant for aluminum from
a zeolite framework in a process which is in some respects
similar to the Pickert process. It is also known that
calcining the H or NH4+ cation forms of zeolites such as
zeolite Y in an environment of water vapor, either extraneous
or derived from dehydroxylation of the zeolite itself, is
effective in removing framework aluminu~ by hydrolysis.
Evidence of this phenomenon is set forth in U.S.P. 3,506,400,
issued April 14, 1970 to P.E. Eberly, Jr. et al.; U.S.P.
3,493,519, issued February 3, 1970 to G.T. Rerr et al.;
and U.S.P. 3,513,108, issued May l9, 1970 to G.T. Kerr.
In those instances in which the crystal structure of the
product composition is retained after the rigorous hydrothermal
-- 3 --
-
12346-1
1~7~837
treatment involved, infrared analysis indicated the presence
of substantial hydroxyl groups exhibiting a stretching
frequency in the area of about 3740, 3640 and 3550 cm 1.
The infrared analytical data of U.S.P. 3,506,400 is especially
instructive in this regard. An explanation of the mechanis~
of the creation of these hydroxyl groups is provided by
Xerr et al. in V.S.P. 3,493,519 wherein the patentees state
that the aluminum atoms in the lattice framework of hydrogen
zeolites can react with water resulting in the removal of
aluminum from the lattice in accordance with the followin~
equation:
O O O
' H
-Si - 0 -Al - O -Si - 0 + 3H20 -~
O O O
O O O
' H
-Si - OH HO-Si-0 +Al(OH)3
O O O
The aluminum removet from its original lattice position is
capable of further reaction with cationic hydrogen, accord-
ing to Kerr et al. to yield aluminum-containing i.e. hydroxo-
aluminum, cations by the equation:
O O O
' H
-Si - O -Al - O - Si - O + Al(OH)
O O O'
Al(OH) +
O O
-Si - O - Al - 0 Si - + H20
O O O
-- 4 --
12346-1
1~71837
It has been su~gested that stabilization ofNH4Y occurs
through hydrolysis of sufficient framework aluminum to for~
stable clusters of these hydroxoaluminum cations within
the sodalite ca~es, thereby holding the zeolite structure
together while the framework anneals itself through the
migration ofsome of the framework silicon atoms.
It is alleged in l~.S.P. 3,594,331, issued July 20,
1971 to C.H. Elliott,that fluoride ions in aqueous media,
particularly under conditions in which the pH is less than
about 7, are quite effective in extracting framework aluminum
from zeolite lattices, and in fact when the fluoride concen-
tration exceeds about 15 grams active fluoride per lO,00
grams of zeolite, destruction of the crystal lattice by
the direct attack on the framework silicon as well as on
the framework aluminum,can result. A fluoride treatment
of thi5 type using from 2 to 22 grams of available fluoride
per 10,000 grams of zeolite (anhydrous) in which the fluorine
is providet by ammonium fluorosilicate is also tescribed
therein. The treatment is carried out for the purpose of
improving the thermal stability of the zeolite. It is
theorized by the patentee tha~ the fluoride in some manner
becomes attached to the constructional alkali metal oxide,
thereby reducing the fluxing action of the basic structural
Na20 which would otherwise result in the collapse of the
crystal structure. Such treatment within the constraints
of the patent disclosure has no effect on either the overall
silicon content of the zeolite product or the silicon content
of a unit cell of the zeolite.
Since stability quite obviously is, in part at least,
a function of the SiO2/A1203 ratio of zeolites,it would
appear to be advantageous to obtain zeolites having higher
12346-1
1~'7~337
proportions of SiO4 tetrahedra by direct synthesis techniques
and thereby avoid the structural changes inherent in frame-
work aluminum extraction. Despite considerabl~ effort in
this regard, however, only very modest success has been
achieved, ~nd this as applied to a few individual species
only. For example, over the seventeen year period since
zeolite Y was first made known ~o the public as a species
having an as-synthesized SiO2/A1203 molar ratio of 3 to 6,
the highest SiO2/A1203 value alle~ed for an as-synthesized
zeolite having the Y structure to date is 7.8 (~etherlands
Patent ~o. 7306078).
We have now discovered, however, a method for removir~
framework aluminum from zeolites having SiO2/Al203 molar
ratios of about 3 or greater and substituting therefor
silicon from a source extraneous to the starting zeolite.
By this procedure it is possible to create more highly
siliceous zeolite species which have the same crystal
structure as ~ould result by direct synthesis if such
synthesis method were known. In general the process comprises
contacting a crystalline zeolite having pore diameters of
at least about 3 Angstroms and having a molar SiO2/A1203
ratio of at least 3, with a fluorosilicate salt, preferably
in an amount of at least 0.0075 moles per 100 grams of zeoli~e
starting material, said fluorosillcate salt being in the
form of an aqueous solution having a pH value in the range
of 3 to about 7, preferably 5 to about 7, and brought into
contact with the zeolite either incrementally or continuouslv
at a 810w rate whereby framework aluminum atoms of the
zeolite are removed and replaced by extraneous silicon atoms
from the added fluorosilicate, It is desirable that the process
is carried out such that at least 60, preferably at least 80, and most
12346-1
1~7~837
preferably at least 90, percent of the crystal structure
of the starting zeolite is retained and the Defect Structure
Factor is less than 0.0~, and preferably less than 0.05
as defined hereina~ter.
The crystalline zeolite starting materials 6uitable
for the practice of the present invention can be any of
the well known naturally occurring or synthetically produced
zeolite species which have pores large enough to permit
the passage of water, fluorosilicate reagents and rea^tion
products through their internal cavity system. These
materials can be represented, in terms o. molar ratios of
oxides, as
M2/n : A123 : x Sio2 : y H20
wherein "M" is a cation having the valence "n", "x" is
a value of at least about 3 and "y" has a value of from zero
to about 9 depending upon the degree of hydration and the
capacity of the psrticular zeolite to hold adsorbed water.
Alternatively, the framework composition can be expressed
as the mole fraction of framework tetrahedra, T02, as:
~AlaSib)02
wherein "a" is the fraction of framework tetrahedral sites
occupied by aluminum atoms and "b" is the fraction of
framework tetrahedral sites occupied by silicon atoms.
The algebraic sum of all of the subscripts within the
brackets is equal to 1. In the above example, a + b = 1.
For reasons more fully explained hereinafter, it is
necessary that the starting zeolite be able to withstand
the initial loss of framework aluminum atoms to at least a
modest degree without collapse of the crystal structure
unless the process is to be carried out at a very slow pace.
In general the ability to withstand aluminum extraction and
`` 12346-1
1~7~337
maintain a high level of crystallinity is directly propor-
tional to the initial SiO2/A1203 molar ratio of the zeolite.
Accordingly it is preferred that the value for "x" in the
formula above be at least about 3, and more preferably
at least about 3.5. Also it is preferred that at least
about 50, and more preferably at least 957, of the A1~4
tetrahedra of the naturally occurring or as-synthesized
zeolite are present in the starting zeolite. Most adva~-
tageously the startin~ zeolite contains as many as possible
of its ori~inal Al04 tetrahedra, i.e. has not been subjected
to anypost-formation treatment which either extensively
removes aluminum atoms from their original framework sites
or converts them from the normal conditions of 4-fold
coordination with oxygen.
The cation population of the starting zeolite is not a
critical factor insofar as substitution of silicon for
framework aluminum is concerned, but since the substitution
mechanism involves the in situ formation of salts of at
least some of the zeolitic cations, it is advantageous
that these salts be water-soluble to a substantial degree
to facilitate their removal from the silica-enriched
zeolite product. It is found that ammonium cations form
the most soluble salt in this regard ar.d it is accordin~ly
preferred that at least 50 percent, most preferably 85
or ~ore percent, of the zeolite cations be ammonium cations.
Sodium and potassium, two of the most common original cations
in zeolites are found to form Na3AlF6 and K3AlF6 respectively,
both of which are only very sparingly soluble in either hot
or cold water. When these compounds are formed as precipitates
within the structural cavities of the zeolite they are quite
difficult to remove by water washing. Tkeir removal, more-
over, is important if thermal stabi'ity of the zeolite
12346-1-C
7~ 8 37
product is desired since the substantial amounts of
fluoride can cause crystal collapse at temperatures as
low as 500~C.
The naturally-occurring or synthetic zeolites used
as starting materials in the present process are composi-
tions well-known in the art. A comprehensive review of
the structure, properties and chemical compositions of
crystalline zeolites is contained in Breck, D.W., "Zeolite
Molecular Sieves," Wiley, New York, 1974. In those in-
stances in which it i8 desirable to replace original
zeolitic cations for others more preferred in the present
process, conventional ion-exchange techniques are suitably
employed. Especially preferred zeolite species are zeo-
lite Y, zeolite rho, zeolite W, zeolite N-A, zeolite L,
and the mineral and synthetic analogs of mordenite clinop-
tilolite, chabazite, offretite and erionite. The fluoro-
silicate salt used as the aluminum extractant and also
as the source of extraneous silicon which is inserted
into the zeolite structure in place of the extracted
aluminum can be any of the flurosilicate salts having
the general formula
~ )2/bS~6
wherein A is a metsll$c or non-metall~c cation other than
H~ hav$ng the ~alence "b". Catlons re~resented by "A" are
~lkylammon~um,NH4+ , Mg~+ , L$+, Na+, K+, Ba++, Cd++, Cu+,
H+, Ca~+, Cs+, Fe~+, Co~+, Pb++, Y,n+~, Rb+ , Ag~, Sr++, Tl+
~nd Zn++. The am~onium cation form o' the fluoros~licate ~s
h~ghly preferred becsuse of ~ts susbstant~al solub~l~ty
$n water ~nd also because the ammonium cations form water
so1uble by-product sa1ts upon reaction with the zeolite,
namely (NH4)3AlF6.
In certain respects, the manner in which the fluoro-
silicate and starting zeo1ite are brought into contact and
_ g _
~.
~1~71B37 12346-l
reacted is of critical importance. We have discovered that
the overall process of substituting silicon for aluminum
in the zeolite framework is a two step process in which
the aluminum extraction step will, unless controlled, proceed
very rapidly while the silicon insertion is relatively very
slow. If dealumination becomes too extensive without sili-
con substitution, the crystal structure becomes seriously
degraded and ultimately collapses. While we do not wish to
be bound by any particular theory, it appears that the fluo-
ride ion is the agent for the extraction of framework aluminu...
in accordance with the equation.
NH4+
O O O O
(~H4)2SiF6 (soln) + A ~ S~ + (NH4)3AlF6 ~soln)
o( o 6 o
Zeolite Zeolite
It is, therefore, essential that the initial dealumination
step be inhibited and the silicon insertion step be
pro~oted to achieve the desired zeolite product. It is
fount that the various zeolite species have ~arying degrees
of resistance toward degradation as a consequence of frame-
work aluminum extraction without silicon substitution. In
general the rate of aluminu~ extraction is decreased as the
pH of the fluorosilicate solution in contact with the
zeolite is increased within the range of 3 to 7, and as the
concentration of the fluorosilicate in the reaction system
is decreased. Also increasing the reaction temperature
tends to increase the rate of silicon substitution. h~hether it is
necessary or desirable to buffer the reaction system or
strictly limit the fluorosilicate concentration is readily
determined for each zeolite species by routine observation.
- 10 -
12346-l
1~'71837
Theoretically, there is no lower limit for the c~ncen-
tration of fluorosilicate salt in the aqueous solution
employed, provided of course the pH of the solution is high
enough to avoid undue destructive acidic attack on the zeolite
structure spart from the intended reaction with the fluoro-
silicate. Very slow rates of addition of fluorosilicate
salts insure that adequate time is permitted for the inser-
tion of silicon as a framework substitute for extracted
aluminum before excessive aluminum extraction occurs with
consequent collapse of the crystal structure. Practical
commercial considerations, however, require that the reaction
proceed as rapidly as possible, and accordingly the conditions
of reaction temperature and reagent cor,centrations should be
optimized with respect to each zeolite starting material.
In general the more highly siliceous the zeolite, the higher
the permissible reaction temperature and the lower the
suitable pH conditions. In general the preferred reaction
temperature is within the range Of 5n to 95C., but tempera-
tures as high as 125C and as low as 20C have been
suitably employed in some instances. At pH values below
about 3 crystal degradation is generally found to be undulv
severe, whereas at pH values higher than 7, silicon inser-
tion is unduly low. The maximum concentration of fluoro-
silicate salt in the aqueous solution employed is, of course,
interdependent with the temperature and pH factors and
also with the time of contact between the zeolite and the
solution and the relative proportions of zeolite and fluoro-
silicate. Accordingly it is possible that solutions having
fluorosilicate concentrations of from about 10-3 moles per
liter of solution up to saturation can be employed, but it
is preferred that concentrations in the range of 0.5 to 1.0
. 12346-l
1~7~83~
moles per liter of solution be used. These concentration
values are with respect to erue solutions, and are not
intended to apply to the total fluorosilicate in slurries
of salts in water. As illustrated hereinafter, even very
slightly soluble fluorosilicates can be slurried in water
and used as a reagent--the undissolved solids being readily
available to replace dissolved molecular species consumed
in reaction with the zeolite. As stated hereinabove, the
amount of dissolved fluorosilicate employed with respect
to the particular zeolite being treated will depend to some
extent upon the physical and chemical properties of the
individual zeolites as well as other specifications herein
contained in this applicàtion. However, the minimum value
for the amount of fluorosilicate to be added should be at
least.equivalent to the minimum mole fraction of aluminum
to be removed from the zeolite.
In this disclosure, including the appended claims,
~n specifying proportions of zeolite starting material
or adsorption properties of the zeolite product, and the
like, the anhydrous state of the zeolite will be intended
unless otherwise stated. The anhydrous state is considered
to be that obtained by heating the zeolite in dry air at
450C for 4 hours.
It is apparent from the foregoing that, with respect
to reaction conditions, it is desirable that the integrity
of the zeolite crystal structure is substantially maintained
throughout the process, and that in addition to having
extraneous (non-zeolitic) silicon atoms inserted into the
lattice, the zeolite retains at least 60 and preferably at
least 90 percent of its original crystallinity. A convenient
technique for assessing the crystallinity of the products
- 12 -
12346-1
117~837
relative to the crystallinity of the starting material is
the comparison of the relative intensities of the d-
spacings of their respective X-ray powder diffraction
patterns. The sum of the peak heights, in terms of arbi-
trary units above background, of the starting material
is used as the standard and is compared with the corres-
ponding peak heights of the products. ~Jhen, for example,
the numerical sum of the peak heights of the product is
85 percent of the value of the sum of the peak heights of
the starting zeolite, then 85 percent of the crystallinity
has been retained. In practice it is common to utilize
only a portion of the d-spacing peaks for this purpose,
as for example, five of the six strongest d-spacings.
In zeolite Y these d-spacings correspond to the Miller
Indices 331, 440, 533, 642 and 555. Other indicia of the
crystallinity retained by the zeolite nroduct are the degree
of retention of surface area and the degree of retention of
the adsorption capacity. Surface areas can be determined
by the well-known Brunauer-Emmett-Teller method (B-E-T).
J. Am. Chem. Soc. 60 309 (1938) using nitrogen as the
atsorbate. In tetermining the atsorption capacity, the
capacity for oxygen at -183C at 100 Torr is preferred.
All available evidence indicates that the
present process is unique in being able to protuce zeolites
essentially free of defect structure yet having molar Si02/
A12O3 ratios higher than can be obtained by direct hydro-
thermal synthesis, The products resulting fro~ the operation
of the process share the common characteristic of having a hi~her
molar Si02/A1203 ratio than previously obtained for each species
by direct hydrothermal synthesis by virtue of containing silicon
from an extraneous, i.e. non-zeolitic, source, preferably in con-
junction with a crystal structure which is characterized as
- 13 -
12346-1
1~l7~837
containing a low level of tetrahedral defect sites. This
defect structure, if present, is revealed by the infrared
spectrum of zeolites in the hydroxyl-stretching region.
In untreated, i.e. naturally occurring or as-synthesized
zeolites the original tetrahedral structure is conventionally
represented as
_1!,
I t
After treatment with a complexing agent such as ethylene-
diaminetetraacetic acid (H4EDTA) in which a stoichiometric
reaction occurs whereby framework aluminum atoms along with
an associated cation such as sotium is removed as NaAlEDTA,
it is postuiatet that the tetrahedral aluminum is replaced
by four protons which form a hydroxyl "nest", AS follows:
;~o~.
_J~
The infrared spectrum of the aluminum depleted zeolite
will show a broad nondescript absorption band beginning
at about 3750 cm 1 and extending to about 3000 cm 1. The
size of this absorption band or envelope increases with
increasing aluminum depletion of the zeolite. The reason
that the absorption band is so broad and without any specific
absorption frequency is that the hydroxyl groups in the
vacant sites in the framework are coordinated in such a way
that they interact with each other (hydrogen bonding).
- 14 -
.. . . .
12346-1
~7~837
The hydroxyl groups of adsorbed water molecules are also
hydrogen-bonded and produce a similar broad absorpti~n
band as do the "nest" hydroxyls. Also,certain other
zeolitic hydroxyl groups, exhibiting specific characteristic
absorption frequencies within the range of interest, will
if present, cause infrared absorption bands in these regions
which are superimposed on the band attributable to the "nest"
hydroxvl groups. These specific hydroxyls are created by
the decomposition of ammonium cations or organic cations
present in the zeolite.
It isl however, possible to treat zeolites, prior to
subjecting them to infrared analysis, to avoid the presence
of the interferrin~ hydroxyl groups and thus be able to
observe the absorption attributable to the "nest" hydroxyls
only. The hytroxyls belonging to atsorbet water are
avoided by sub~ecting the hydrated zeolite sample to vacuum
activation at a moderate temperature of about 200C. for
about 1 hour. This treatment permits desorption ant removal
of the atsorbed water. Complete removal of adsorbed water
can be ascertained by noting when the infraret absorption
bant at about 1640 cm 1, the bending frequency of water
molecules, has been removed from the spectrum.
The decomposable ammonium cations can be removed,
at least in large part, by ion-exchange ant replaced with
metal cations, preferably by subjecting the ammonium form
of the zeolite to a milt ion exchange treatment with an
aqueous NaCl solution. The OH absorption bands produced
by the thermal decomposition of ammonium cations are thereby
avoided. Accordingly the absorption band over the range of
3745 cm 1 to about 3000 cm 1 for a zeolite so treated is
almost entirely attributable to hydroxyl groups associated
- 15 -
12346-1
1~7~837
with defect structure and the absolute absorbance of this
band can be 8 measure of the degree of aluminum depletion.
It is found, however, that the ion-exchange treat~ent,
which must necessarily be exhaustive even though mild,
requires considerable time. Also the combination of the
ion-exchange and the vacuum calcination to remove adsorbed
water does not remove every possible hydroxyl other than
tefect hydroxyls which can exhibit absorption in the 3745 cm 1
to 3000 cm 1 range. For instance, a rather sharp band at
3745 cm 1 has been attributed to the Si-OH groups situated
in the terminal lattice positions of the zeolite crystals
and to amorphous (non-zeolitic) silica from which physically
adsorbed water has been removed. For these reasons we
prefer to use a somewhat different criterion to measure
the tegree of tefect structure in the zeolite products of
this invention.
In the absence of hydrogen-bondet hytroxyl groups
contributet by physically atsorbet water, the absorption
frequency least affected by absorption due to hydroxyl
groups other than those associatet with framework vacancies
or tefect sites i9 at 3710 + 5 cm 1, Thus the relative
number of tefect sites remaining in a zeolite product of
this invention can be gauged by first removing any adsorbed
water from the zeolite, tetermining the value of the absolute
absorbance in its infraret spectrum at a frequency of 3710
cm 1, and comparing that value with the corresponding value
obtainet from the spectrum of a zeolite having a known
quantity of defect structure. The following specific proce-
dure has been arbitrarily selected and used to measure the
amount of defect structure in the products prepared in the
- 16 -
12346-1
~71837
Examples appearing hereinafter. Using the data obtained
from this procedure it is possible, using simple mathematical
calculation, to obtain a single and reproducible value
hereinafter referred to as the "Defect Structure Factor",
denoted hereinafter by the symbol "z", which can be used
in comparing and distinguishing the present novel zeolite
compositions from their le~s-siliceous prior known counter-
parts and also with equally siliceous prior known counter-
parts prepared by other techniques.
DEFECT STRUCTURE FACTOR
.
(A) Defect Structure Zeolite Standard.
Standarts with known amounts of defect structure can
be prepared by treating a crystalline zeolite of the same
species as the product sample with ethylenediaminetetraacetic
acit by the standart procedure of Kerr as tescribed in U.S.
Patent 3,442,795. In order to prepare the stantard it is
impostant that the starting zeolite be well crystallized,
substantially pure and free from tefect structure. The
first two of these properties are readily tetermined by
conventional X-ray analysis and the third by infrarcd
analysis using the procedure set forth in part (B) hereof.
The protuct of the aluminum extraction shoult also be well
crystallized ant substantially free from impurities. The
amount of aluminum tepletion, i.e., the mole fraction of
tetrahedral tefect structure of the standard samples can
be ascertainet by conventional chemical analytical procedure.
The molar SiO2/A1203 ratio of the ~tarting zeolite used
to prepare the standard sample in any ~iven case is not
narrowly critical, but is preferably within about 10% of
the molar SiO2/Al203 ratio of the same zeolite species used
as the starting.material in the practice of the process of
- 17 -
.
12346-1
~3l7g~837
the present invention.
(B) Infrared Spectrum of Product Sample and Defect
Structure Zeolite Standard.
Fifteen milligrams of the hydrated zeolite to be
analyzed are pressed into a 13 mm. diameter self-supporting
wafer in a KBr die under 5000 lbs. pressure. The wafer i5
then heated at 200C for l hour at a pressure of not greater
than 1 x lO 4mm. Hg to remove all observable traces of
physically adsorbed water from the zeolite. This condition
of the zeolite is evidenced by the total absence of an
infrared absorption band at 1640 cm 1. Thereafter, and
without contact with adsorbable substances, particularl~:
water vapor, the infrared spectrum of the wafer is obtained
on an interferometer system at 4 cm 1 resolution over the
frequency range of 3745 to 3000 cm 1, Both the product
sample and the stantart sample are analyzed using the same
interferometer system to avoid discrepancies in the analysis
due to different apparatus. The spectrum, normally obtained
in the transmission mode of operation is mathematically
converted to and plotted as wave number vs. absorbance.
(C) Determination of the Defect Structure Factor.
The defect structure factor (z) is calculated by
substituting the appropriate tata into the following
formula:
Z 3 M s) X ~Mole fraction of defects in the standard~
( P _ _ _ _ _ _
AA(std)
wherein AA(ps) is the infrared absolute absorbance measured
above the estimated background of the product sample at
3710 cm 1; AA(Std) is the absolute absorbance measured
above the background of the standard at 3710 cm 1 and the
mole fraction of defects in the standard are determined in
accordance with part (A) above.
- 18 -
12346-1
~7~837
Once the defect structure factor, z, is known, it is
possible to determine from wet chemical analysis of the
product sample for Si02, A1203 snd the cation content as
M2/n0 whether silicon has been substituted for aluminum
in the zeolite as a result of the treatment and also the
efficiency of any such silicon substitution.
For purposes of simplifying these determinationS the
framework compositions are best expressed in terms of mole
fractions of framework tetrahedra T~ . The starting zeolite
may be expressed as:
( Al cl o )
whereas "a" is tne mole fraction of aluminum tetrahedra in
the framework; "b" is the mole fraction of silicon tetra-
hedra in the framework; O denotes defect sites and "z" is thé
mole fraction of defect sites in the zeolite framework. In
many cases the "z" value for the starting zeolite is zero
and the defect sites are simply eliminated from the expression
Numerically the sum of the values a ~ b + z ~ 1.
The zeolite product of the fluorosilicate treatment,
expressed in terms of mole fraction of framework tetrahedra
(TO2) will have the form
rAl(a-N)sib+(N-~z)oz ?2
wherein: "N" is defined as the mole fraction of aluminum
tetrahedra removed from the framework during the treatment
"a" is the mole fraction of aluminum tetrahedra present in
the framework of the starting zeolite; "b" is the mole
fraction of silicon tetrahedra prescnt in the framework
of the starting zeolitei "z" is the mole fraction of
defect sites in the framework; (N-~z) is the mole fraction
increase in silicon tetrahedra resulting from the fluoro-
silicate treatment; "~z" is the net change in the mole
- 19 -
12346-1
~L~7~8~37
fraceion of defect sites in the zeolite framework resulting
from the treatment
~ Z ~ Z(product zeolite)- Z(startin~ zeolite)
The term Defect Structure Factor for any given zeolite is
equivalent to the "z" value of the zeolite. The net change
in Defect Structure Factors between the starting zeolite
and the product zeolite is equivalent to "~2". Numerically,
the sum of the values:
(a-N) + ~ + (N- ~z)] + z = 1
The fact that the present process results in zeolite
products having silicon substituted for aluminum in the
framework is substantiated by the framework infrared
spectrum in addition to the hydroxyl region infrared
spectrum. In the former, there is a shift to higher wave
numbers of the indicative peaks and some sharpening thereof
in the case of the present products,as compared to the
starting zeolite,which is due to an increaset SiO2/A1203
molar ratio.
The essential X-ray powder diffraction patterns appear-
ing in this specification and referred to in the appended
claims are obtained using standard X-ray powder diffraction
techniques. The radiation source is a high-intensity,
copper target, X-ray tube operated at 50 K~ and 40 ma.
The diffraction pattern from the copper ~ radiation and
graphite monochromator is suitably recorded by an X-ray
spectrometer scintillation counter, pulse-height analyzer
and strip-chart recorder. Flat compressed powder samples
are scanned at 2 (2 theta) per minute, using a 2 second
time constant. Interplanar spacings (d) are obtained from
the position of the diffraction peaks expressed as 20, where
6 is the Bragg angle as observed on the strip chart. Inten-
sities are determined from the heights of diffraction peaks
- 20 -
~ ~ 7 1 8 3 7 12346
after substracting background.
In deter~ining the cation equivalency, ~.e. the molar
ratio M2/nO/A1203, in each zeolite productl it is advantageous
to perform the routine chemical analysis on a form of the
zeolite in which "M" is a monovalent cation other than
hydrogen. This avoids the uncertainty which can arise in
the case of divalent or polyvalent metal zeolite cations
as to whether the full valence of the cation is employed
in balancing the net negative charge associated with each
A104-tetrahedron or whether some of the positive valence of
the cation is used in bonding with OH or H30~ ions.
The preferred novel crystalline aluminosilicate compositions of
the present invention will contain a chemical or molar
framework composition which can be determined from the
expression of mole fractions of framework tetrahedra pre-
viously tescribed;
[Al(a-N)Sib~(N-~z)Oz _702
wherein: the framework Si/Al ratio is teterm$ned by
b + N-az and is numerically 34; the mole fraction of the
a-N
aluminum tetrahedra removed from the framework of the starting
zeolite, N, is ~0.3a, the mole fraction of silicon tetrahedra
substituted into the framework of the product zeolite
(N-^z) is increased by at least a value for N-az which
is numerically ~0,5, the change in Defect Structure Factor
~z is increased by less than 0,08 ana ~referably less than
0,05.
- 21 -
12346-1
1~711 337
Moreover, regardless of the Defect Structure Factor of
any zeolite material which has been treated ac~ording to
the present process, it is novel by virtue of having had
extraneous silicon inserted into its crystal lattice
and having 8 molar SiO2/A1203 ratio greater than heretofore
obtained by direct hydrothermal synthesis. This $s necessarily
the case since all other methods for increasing the SiO2/A1203
ratio of a zeolite crystal must remove framework aluminu~ -
atoms, and unless at least one of those removed aluminum
atoms is replacet by a silicon atom from a source other
than the crystal itself, the absolute defect structure
content of the crystal must be greater than the product
of the present invention.
Crystal structures are more commonly described in terms
of the number of tetrahedra in a unit cell. The unit cell
is the basic structural unit that is repeated throughout
the crystal. The number of tetrahedra in a unit cell vary
widely among the various zeolite species, however. For
example, the unit cell of offretite contains only 18 tetra-
hedra whereas the unit cell of faujasite or a Y-type zeolite
contains 192 tetrahedra. Hence the substitution of one
extraneous silicon atom for one framework aluminum atom in
each unit cell of offretite has a disproportionately larger
effect than the same single atom substitution per unit cell
of faujasite. This substantial disparity can be ameliorated
to a considerable degree by regarding the framework substi-
tutions as changes in the framework density of the zeolites
involved, which can be expressed as the number of framework
tetrahedra per lO,OOOA3. Most zeolites have a framework
density of from about 130 to 190 tetrahedra per lO,OOOA3.
A more detailed description of framework density has been
published by W.M. Meier, "Proceedings of the Conference on
- 22 -
: 12346-1-C
~7~B37
Molecular Sieve (London, April 1967)," Society of Chemi-
cal Intustry, (1968) pg. 19 et ~eq.
Accordingly, the novel cry6tall~ne aluminos~licstes of
the present Invent~on include:
Zeolite LZ-210 having, in the dehytrated ~tate, a
chemical composition expressed in terms of mole ratios of
oxides as
2/n 2 3 x S~02
wherein "M" is a cation having the valence "n" ~nd "x"
is a value greater than 8, preferably greater than 9 ~re
preferably and w~thin the range of 9 to 60, having an X-
ray powder diffraction pattern having at least the d-
spacings set forth in ~able A, below, and havin~ extraneous
~ilicon atoms in its crystal lattice in the form of SiO4
tetrahedra, preferably $n an avera~e amount of at least 1.0
per lO,OOOA3.
A more lim~ted subcla6s of LZ-210 compositions, i.e.
those whlch are charactesized by having both high molar
SiO2/A1203 ratios and low Defect Structure Factors, csn be
tefined as having a chemical composition expresset in terms
of mole fractions of framework tetrahedra as:
~ Al(a-N)Sib~ ~-~z ~z -7 2
wherein: the mole fraction of aluminum -N- removed from the
framework of the starting zeolite i8 at least 0.03a; b+N- z
has a value 4 and preferably greater than 4.5; the change
in defect structure factor z iB less than 0.08 and pre-
ferably less than 0.05; an increased silicon content in the
framework, = , of at least O.S; and a cation equivalent
expressed
1~71~337
12346-1-C
as a monovalent cation species, M+/Al, from 0.8S to 1.1 and
the characteristic crystal structure of zeolite Y as
indicated by an X-ray powder diffraction pattern having at
least the d-spacings set forth broadly in Table A, and more
narrowly in Table B, below.
TABLE A TABLE B
d(A~ Intensity d(A) Intensitv
14.17-13.97 very strong 14.17-14.09 very strong
8.68- 8.55 medium 8.68- 8.62 medium
7.40- 7.30 medium 7.40- 7.35 medium
5.63- 5.55 medium 5.63- 5.5~ medium
4.72- 4.66 medium 4.72- 4.69 medium
4.34- 4.28 medium 4.34- 4.31 medium
3.74- 3.69 strong 3.74- 3.72 strong
3.28- 3.23 strong 3.28- 3.26 strong
2.83- 2.79 strong 2.83- 2.81~ strong
The LZ-210 zeolite as defined above will have a cubic unit
cell dimension, aO, o~ less than 24.55 Angstroms,
preferably from 24.20 to 24.55 Angstroms and, when the
molar SiO2/A1203 ratio is less than 20, an adsorption
capacity for water vapor at 25C and 4.6 Torr water vapor
pressure of at least 20 weight percent based on the
anhydrous weight of the zeolite, and preferably an oxygen
adsorption capacity o 100 Torr and -183C of at least 235
weight percent.
- 24 -
1~7~837 12346-1
LZ-210 can be prepared from a conventionally prepared
zeolite Y which has a molar SiO2tA1203 ratio of less than
8 by using the present process to increase the SiO2/A1203
ratio greater than 8. A preferred procedure is the process
embodiment which comprises.
(a) providing a zeolite Y composition havin~ a
molar SiO2/A1203 ratio of not greater than 7, preferably
between 3 to 6;
(b) contacting and reacting at a temperature of from
20 to 95C, said zeolite Y with a fluorosilicate, preferably
ammonium fluorosilicate, in an amount of at least as great
as the value "N", defined supra, wherein "N" is equal to or
greater than 0.3a.
It can also be stated that:
AFS - 1.395a - 0,275
wherein AFS is the minimum number of moles of ammonium fluorosi-
licate per 100 gm (anhydrous weight) of zeolite starting
material ant "a" is the mole fraction of framework aluminum
atoms in the zeolite starting material as statet in
~AlaSib~z)02~ sait fluorosilicate being in the form of an
aqueous solution at a pH in the range of 5 to about 7, the
fluorosilicate solution being brought into contact with
the zeolite either incrementally or continuously at a slow
rate such that a sufficient proportion of the framework
- 25 -
12346-1
1~7~37
aluminum atoms removed are replaced by silicon atoms to
retain at least 80 percent, preferably at least 90 percent,
of the crystal structure of the starting zeolite Y; and
(c) isolating the zeolite having an enhanced frame-
work silicon content from the reaction mixture.
The starting zeolite Y composition can be synthesized
by any of the processes well known in the art. Representa-
tive processes are disclosed in ~.S.P. 3,130,007.
Another novel zeolite composition of the present
invention is LZ-211 which has, in the dehydrated state and
prior to calcination at a temperature in excess of 200C.,
a chemical composition expressed in terms of mole ratios
of oxides as
(o 9 ~ 0.1) M2~nO : A1203 : x Si2
wherein "M" is an inorganic cation having the valence "n",
preferably H , NH4 or a metallic cation, and x is a value
greater than 15, preferably within the range of 17 to 120,
and most preferably from 17 to 35, having the characteristic
crystal structure of mordenite as indicated by an X ray
powder diffraction pattern having at least the d-spacings
set forth in Table C, below, and having extraneous silicon
atoms in its crystal lattice in the form of SiO4 tetrahedra,
preferably in an average amount of at least 1.0 per 10, ocoA
_ 26 -
12346-1
1~7~37
TABLE C
d(A) Intensity
13.5 + 0.2 Medium
9.0 + 0.2 Strong
6.5 + 0.1 Strong
4.5 + 0.1 Medium
4.0 + 0.1 Medium
3.8 ~ 0.1 Medium
3.5 + 0.1 Strong
3 4 + 0.1 Strong
3.2 + 0.1 Strong
A more limited subclass of LZ-211 compositions, i.e.
those which are characterized by having both high molar
SiO2/A1203 ratios and low Defect Structure Factors, can
be defined as havin~ a chemical composition expressed in
terms of mole fractions of framework tetrahedra as:
[Al(a-N)Sib+(N-~z ~z ]2
wherein: the mole fraction ofaluminum, N, removed from
the framework of the starting zeolite is at least 0.3a;
the Si/Al ratio has a vlaue 7.5, preferably within the
range 8.5 to 30; an increase in the Defect Structure Factor
"~z" of less than 0.08, an increase of silicon in the frame-
work, N-~z, of st least 0.5i a cation equivalent expressed
as a monovalent cation species M /Al of 0.9 1 0.1.
The precursor of LZ-211, i.e. the starting mordenite
zeolite, can be any naturally-occurring or synthetic form
of mordenite having a molar SiO2/A1203 ratio of not greater
than 12, and in the case of the synthetic forms, svnthesized
in the substantial absence of organic cations. It is
- 27 -
12346-l
l~t7~837
immaterial whether the starting mordenit~ is of so-called
small pore or large pore varieties.
The novel zeolites denominated L~-214 are the more
siliceous forms of the prior known zeolite Rho and are
prepared therefrom using the present process for ~ilicon
substitution. LZ-214 has, in the dehydrated state, a
chemical composition expressed in terms of mole ratios of
oxides
0-9 + 0-1 M2/n A123 x SiO2
wherein "M" is a cation having the valence "n" and "x"
is a value greater than 7, preferably in the range of
8 to 60, the characteristic crystal structure of zeolite
Rho as inticatet by an X-ray powter diffraction pattern
having at least the d-spacings set forth in Table D, belo~
and having extraneous silicon atoms in its crystal lattice
ln the form of SiO4 tetrahedra, preferably in an amount of
at least 1.0 per lO,OOOA3.
TABLE D
t(A) Relative Intensitv
10.5 + 0.3 . Very Strong
6.1 + 0.2 Metium Strong
4.7 + 0.2 Medium
3.52 + 0.1 Metium
3.35 + 0.1 Medium
2.94 + 0.1 Medium
2.65 + 0.1 Medium
- 28 -
,
1~7~3~ 12346-1-C
A more limited subclass of LZ-214 compositions, i.e.
those which are characterized by having both high molar
SiO2/A12O3 ratios and low Defect Structure Factors,
can be defined as having a chemical composition e~pressed
in terms of mole fraction of framework tetrahedra as:
[A1(a N) Slb+(N-~z)O z]2
wherein: the mole fraction of aluminum, N, removed from the
framework of the starting zeolite Rho is at least 0.3a; the
Si/Al has a value ~4 preferably within the range 4.5 to
30; an increase in the Defect Structure Factor n az" of
less than 0.08, an increase of silicon in the framework,
N- ~z, of at least 0.5: a cation equivalent expressed as a
N
monovalent cation species ~+/Al of 0.9 + 0.1. Zeolite Rho
and the method for its manufacture are set forth in U.S.P.
3,904,738 issued September 9, 1975, and which is
incorporated herein by reference.
The noval zeolites denominated L2-212 are the more
siliceous forms of the prior known zeolite L and are pre-
pared therefrom using the present process for silicon sub-
stitution. LZ-212 has, in the dehydrated state, a chemical
composition expressed in terms of mole ratios of oxides
0.9 + 0.1 M2/nO : A12O3 : x SiO2
wherein "M" is a cation having the valence "n" and "x" is
a value greater than 8, pre~eraDly in the range of 9 to 60,
- 29 -
1~7~37 12346-1
the characteristic crystal structure of zeolite L as
indicated by an X-ray powder diffraction pattern having
at least the d-spacings set forth in Table E, below, and
having extraneous silicon atoms in its crystal lattice in
the form of SiO4 tetrahedra, preferably in an amount of
at least 1.0 per lO,OOOA3.
TABLE E
d(A) Relative Intensity
15.8 + 0.2 Strong
6.0 + 0.1 Medium
5.8 + 0.1 Medium weak
4.6 + 0.1 Medium
4.4 + 0.1 Medium
4.3 + 0.1 .Medium
3.9 + 0,1 Medium
3.66 + 0.1 Medium
3.48 + 0,1 Medium
3.28 + 0.1 Medium
3,18 + 0,1 Medium
3,07 + 0.1 Medium
2.91 + 0.1 Medium
A more limited subclass of LZ-212 compositions, i.e,
those which are characterized by having both high molar
5102/A1203 ratios and low Defect Structure Factors, can
be defined as having a chemical composition can be expressed
in terms of mole fraction of framework tetrahedra as:
- 30 -
1~7~37 12346-1-C
[Al(a-N)Slb+(N-~z)G z]2
wherein: the mole fraction of aluminum, N, removed from the
framework of the starting zeolite L is at least 0.3a; the
Si/Al has a value 34; and increase in the Defect Structure
Factor, ~ z, of less than ~.08, an increase of silicon in
the framework, N~__ , of at least 0.5; a cation
equivalent expressed as a monovalent cation species M+/Al
of 0.9 + 0.1. Zeolite L and the method for its manufacture
are set forth in U.S.P. 3,216,789 issued November 9, 1965.
The novel zeolites denominated LZ-215 are the more
siliceous forms of the prior known zeolite N-A and are
prepared therefrom using the present process for silicon
substitution. LZ-215 has, in the dehydrated state, a
chemical composition expressed in terms of mole ratios of
oxides
0.9 + 0.1 M2/nO : A12O3 : x SiO2
wherein "~-- is a cation having the valence "n" and "x" is a
value greater than 8, preferably in the range of 10 to 30,
the characteristic crystal structure of zeolite N-A as
indicated by an X-ray powder diffraction pattern having at
least the d-spacin~ set forth in Table F, below, and having
extraneous silicon atoms in its crystal lattice in the form
of SiO4 tetrahedra, preferably in an amount of at least
1.0 per 10,000 A3.
- 31 -
12346-1
117~837
~ABLE F
d(A) _ Relative IntensitY
.
12.0 ~ 0.5 Very ~trong
B.5 ~ 0.5 Very strong
6.9 ~ 0.2 Stron~
5-4 ~ -~ Medium
4.2 ~ 0.1 Medium
4.0 ~ 0.1 Strong
3.62 ~ 0.1 Very strong
3.33 ~ 0.1 Medium
3.20 ~ 0.1 Medium
-
2.91 ~ 0.1 Medium
A ~ore limitèd subclass of LZ-215 co~positions, i.e.
those which are characterized by having both high molar
SiO2/A1203 ratios and low Defect Structure ~actors, can
be defined as having a che~ical compo6ition can ~e expressed
~n terms of mole fractions of framework tetrahedra as:
~ Al(a.N)S~+~N-~z ~z 702
wherein: the mole fraction of aluminum N, removed from
the framework of the starting zeolite N-A is st least 0.3a;
the Si/Al has a ~alue~4, preferably within the range 5
to 30; an increase in the Defect Structure Factor~Dz" of
less than ~,08, n increase of 6~1icon in the framework
__ff_, of at lesst 0.5; 8 cation equivalent e:;pressed as a
monovalent cation 6pecies M /Al of O . 9 ~ O . 1 . Zeolite ~-A
and the method for its manufacture are 6et forth in U.S.P,
3,306,922 issued February 23, 1967,
- 32 -
1~7~837 12346-1
The novel zeolites denominated LZ-216 are the more
siliceous forms of the prior known zeolite W and are
prepared therefrom using the present process for silicon
substitution. LZ-216 has, in the dehydrated state, a
chemical composition expressed in terms of mole ratios of
oxides
O g + 0.1 M2~nO : A1203 : x SiO2
wherein "M" is a cation having the valence "n" and "x"
is a ~alue greater than 8, preferably in the sange of
to 60, the characteristic crystal structure of zeolite
W as indicated by an X-ray powder tiffraction pattern havin~
at least the d-spacings set forth in Table G, below, and
having extraneous silicon atoms in its crystal lattice in
the form of SiO4 tetrahedra, preferahl~ in an amount of
at least 1.0 per lO,OOOA3.
TABLE G
t(A) _ Relative Intensitv
8.2 + 0.2 Medium Strong
7.1 + 0.2 Very Strong
5.3 + 0.1 Metium Strong
S.0 + 0.1 Medium Strong
4.5 + 0.1 Medium
4.31 + 0.1 Metium
3.67 + 0.1 Medium
12346-1-C
1~7~837
TABLE G (continued)
d(A) _ Relative Intensity
3.25 t 0.1 Strong
3.17 ~ 0.1 Strong
2.96 ~ 0.1 Medium
2.73 ~ 0.1 Medium
2.55 ~ 0.1 Medium
A more limited ~ubclass of LZ-216 compositions, i.e.,
those which are characterized by having both high molar
SiO2/A1203 ratios and low Defect Structure Factors, can
be defined as having a chemical composition expressed
$n terms of mole fractions of framework tetrahedra as:
[Al(a_N)Sib+(N-~ z) z- 2
wherein: the more fraction of aluminum, N, removed from
the framework of the starting zeolite W is at least 0.3a;
the Si/Al has a value ~ 4, an increase in the Defect
Structure Factor, ~ z, of less than 0.08, an increase of
silicon in the framework N- z, of at least 0.5; a cation
equivalent expressed as a monovalent cation species M+/Al
of 0.9 ~ 0.1. Zeolite W and the method for its manufac-
ture are set forth in U.S~P. 3,012,853 issued December
12, 1961.
The novel zeolites denominated LZ-217 ase the more
6iliceous forms of the prior known zeolite mineral offre-
t~te and $ts 6ynthetic analogues, zeolite 0 and ~MA-~ffretite,
and are prepared therefrom using the present process for
6ilicon 6ubstitut$0n. LZ-217 has, in the dehydrated state,
a chemical composition expressed in terms of mole ratios of
oxides:
- 34 -
~7~837 12346-1
o g ~ 0.1 M2~nO : A1203 : x Si2
wherein M is a cation havin~ the valence "n" and "x"
has a value ~f at least 8 and the characteristic crystal
structure of offretite as indicated by an X-ray powder
diffraction pattern having at least the d-spacings set
forth in Table H, below, and having extraneous silicon
atoms in its crystal lattice in the form of SiO4 tetra-
hedra, preferably in an amoun~ of at least 1.0 per 10,~0~.i3.
TABLE H
d(A) Relative Intensitv
11.4 + 0.2 Very Strong
6.6 + 0.1 Medium Strong
5.7 + 0.1 Medium Weak
4 31 + 0.1 Medium
3,75 + 0.1 Medium
3.58 + 0.1 Medium
3.29 + 0.1 Medium
3.14 + 0.1 Medium
2.84 ~ 0.1 Medium Strong
2.67 + 0.1 Medium Weak
A more limited subclass of LZ-217 compositions, i.e.
those which are characterized by having both high molar
S~02/A1203 ratios and low Defect Structure Factors, can be
defined as having a chemical composition expressed in terms
of mole fractions of framework tetrahedra as:
~Al(a_N)Sib+(N-~ ~z _702
- 35 -
1~7~37 12346-1
wherein: the mole fraction of aluminum, N, removed from
the framework of the starting zeolite offretite is at
least 0.3a; the Si/Al has a value ~4, an ir.cre~s~ in thL
Defect Structure Fact~r, ~z, of less than 0.08, an increase
of silicon in the framework, ~-~z, of at least 0.5; a
N
cation equivalent expressed as a monovalent cation s?~cies
M /Al of 0.9 ~
The n~vel zeolites denominated LZ-218 are the more
siliceous forms of the prior known zeolite mineral chaba-
zite and the structurally related synthetic zeolite ~ zeolite G,
and zeolite D, and are prepared therefrom using the present
process for silicon substitution. LZ-218 has, in the
tehydrated state, chemical composition expressed in terms of
mole ratios of oxides:
o,g + 0 1 M2~nO : A1203 : x Si2
wherein M is a cation having the valence "n" and "x" has
a value of greater than 8, preferably in the range of
8 to 20, and the characteristic crystal structure of chaba-
zite as inticated by an X-ray powder diffraction pattern
having at least the d-spacings set forth in Table I, below.
ant having extraneous silicon atoms in its crystal lattice
in the form of SiO4 tetrahedra, preferably in an amount of
at least 1.0 per lO,OOOA3.
- 36 -
.. . . . .
13 7~837 12346~1-c
TA BLE
d(A) Relative IntensitY
9.2 + 0.3 Very Stron~
6 .8 + O. 2 Medium
5.5 ~ 0.2 Medium
4.9 + 0.2 Medium
4.3 + 0.1 Very Strony
3.53 + 0.1 Medium
3.43 + 0.1 Medium
2.91 + 0.1 Medium Strong
A more limited subclass of L2-218 compositions, i.e.
those which are characterized by having both higher molar
SiO2/A12O3 ratios and low Defect Structure Factors,
can ~e defined as having a chemical composition expressed
in terms of mole fraction of framework tetrahedra as:
~Al(a_N)Sib+(N_aZ) z~2
wherein: the mole fraction of aluminum, N, removed from the
framework of the starting zeolite is at least 0.3a; the
~i/Al has a value 34 an increase in the Defect Structure
Factor, z, of less than 0.08, an increase of silicon in
the framework, N~NZ of at least 0.5; a cation equivalent
expressed as a monovalent cation s~e~-ies ~+/A1 of 0.9 + 0.1.
The novel zeolites denominated LZ-219 are the more
siliceous æorms of the prior known zeolite mineral
clinoptilolite, and are prepared therefrom using the
present process for silicon substitution. LZ-219 has, in
the dehydrated state a chemical composition expressed in
terms of mole ratios of oxides:
''~1
1~7~37 12346-1-C
0.9 + 0.1 M2/nO : A12O3 : x SiO2
wherein M is a cation having the valence ~n" and "x" has a
value of greater than 11, preferably in the range of 12 to
20, and the characteristic crystal structure of
clinoptilolite as indicated by an X-ray powder dif~raction
pattern having at least the d-spacings set forth in Table
J, below, and having extraneous silicon atoms in its
crystal lattice in the form of SiO4 tetrahedra,
preferably in an amount of at least 1.0 per lO,OOOA .
TA~LE I
d(A) Relative Intensity
8.9 + 0.2 Very Strong
7.B + 0.2 Medium
6.7 + 0.2 Medium Weak
6.6 + 0.2 Medium Weak
-
5.1 + 0.2 Medium Weak
3.95 + 0.1 Medium Strong
3.89 + 0.1 Medium
3.41 + 0.1 Medium
3.33 + 0.1 Medium
3.17 + 0.1 Medium
A more limited subclass o~ LZ-219 compositions, i.e.
those which are characterized by having both higher molar
SiO2/A12O3 ratios and low Defect Structure Factors,
can be defined as having a chemical composition, ex~ressed
in terms of mole fraction of framework tetrahedra as:
[Al(a N)Slb+(N aZ)nZ ]2
- 38 -
.,
~. ~
13l7~837
12346-1-C
wherein the mole fraction of aluminum removed, "N", from
the starting clinoptilolite is at least 0.3a; a Si/Al ratio
of ~5.5, preferably greater than 6.0, an increase in tne
Defect Structure Factor, ~z of less than 0.08; an increase
of silicon in the framework, ~ of at least 0.5, a
cation equivalent expressed as a monovalent cation s~ecies
~+/Al o~ O . 9 + O . 1 .
The novel zeolites denominated LZ-220 are the core
siliceous forms of the prior known mineral erionite and its
synthetic analog, zeolite T, and are prepared therefrom
using the present process for silicon substitution. LZ-220
has, in the dehydrated state a chemical composition
expressed in terms of mole ratios of oxides:
o.g + 0.1 M2~nO : A12O3 x S 2
wherein M is a cation having the valence "n" and "x" has a
value of at least 8, and preferably in the range of 8 to
20, and having the characteristic crystal structure of
erionite as indicated by an X-ray powder diffraction
pattern having at least the d-spacings set forth in Table
K, below, and having e~traneous silicon atoms in its
crystal lattice in the form of SiO4 tetrahedra,
preferably in an amount of at least 1.0 per lO,OOOA3.
~A~LE K
d~A) Relative IntensitY
11.3 ~ 0.5 Very 6trong
6.6 ~ 0.2 Str~ng
4.33 ~ 0.1 Medium
3.82 ~ 0.1 Medium
3.76 ~ 0.1 Medium
3.31 ~ 0.1 ~edium
2.66 ~ 0.1 ~edium
2.81 ~ 0.1 Medium
- 39 -
X
~ B37 12346-1-C
A more limited subclass of L~-220 compositions, i.e.
those which are characterized by having both high molar
SiO2/A12O3 ratios and low Defect Structure Factors,
can be defined as having a chemical composition expressed
in terms of mole fraction of framework tetrahedra as:
[Al(a-N)Sib+(N_~z)Ozlo2
wherein the mole fraction of aluminum, N, removed from the
starting zeolite erionite, is at lease 0.3a; the Si/Al has
a value S4,0 and preferably geeater than 5.0; an increase
in the Defect Structure Factor, ~z, of less than 0.08, an
increase or silicon in the framework N-~z of at least
0.5; a cation equivalent expressed as a monovalent cation
species M+/Al of 0.9 + 0.1.
The novel zeolites denominated LZ-213 are the more
siliceous forms of the prior known zeolite Omega and are
prepared therefrom using the present process for silicon
substitution. LZ-213 has, in the dehydrated state, a
chemical composition expressed in terms of mole ratios of
oxides
0.9 + 0.1 M2/nO : A12O3 : x SiO2
wherein M is a cation having a valence "n" and "x" is a
value greater than 20, preferably in the range of 22 to 60,
and the characteristic crystal structure of zeolite Ome~a
as indicated by an X-ray powder diffraction pattern having
at least the d-spacings set forth in Table ~, below, and
having extraneous silicon atoms in its crystal lattice in
the form of SiO4 tetrahedra, preferably in an amount of
at least 1.0 per 10,000A3.
- 40 -
. ., . ~,
1~L7~37
12346-1-C
TABLE L
d(A~ Relaeive Intensitv
15.8 + 0.4 Medium
9.1 1 0.2 Very Str~ng
7.9 + 0.2 Medlum
6.9 + 0.2 Medium
5.95 + 0.1 Medium
4.69 + 0.1 Medium
3.79 ~ 0.1 Very Strong
3.62 + 0.05 Medium
3.52 + 0.1 Medium
A more limited subclass of LZ-213 compositions, i.e.
those which are characterized by having both high ~olar
SiO2/A12O3 ratios and low Defect Structure Factors,
can be defined as having a chemical composition expressed
in terms of mole fractions of framework tetrahedra as:
[Al(a-N)slb=(N-~z)oz~o2
wherein the mole fraction of aluminum, N, removed from the
starting zeolite Omega is at least 0.3a; the Si/Al has
value S10, and preferably in the range of 11 to 30 an
increase in the Defect Structure Factor, ~z, of less than
0.08, an increase of silicon in the framework, ~ _ , of
at lease 0.5; a cation equivalent expressed as a monovalent
cation species ~+/Al of 0~9 + 0.1.
In general it is preferred that the cation equivalent
of every novel composition of the present invention,
expressed as a monovalent cation species M+/Al, is at
least 0.8, and more preferably at least 0.85. With
respect to those particular species herein which have
been denominatea as "LZ" and a three digit number,
the cation equivalent values speciried for
_ 41 -
~17~837 12346-1
each species subclass is also the preferred valu~ for the
other members of the mor~ broadly defined members ~f each
particular species.
The invention is illustrated by the procedures and
products of the following examples:
ExamPle 1
.
(a) 396 grams of (NH4)2SiF6 were dissolved with stirrin~
in 3 liters of distilled water at 50C. This solution was
put into a dropping funnel fitted on a three-necked round-
bottom flask. A solution of 6400 grams of ammonium acetate
in 8 liters of water was then added to the flask. An 85~'
am~.,onium exchanged zeolite NaY in the amount of 1420
grams (hydrated weight, molar Si02/A1203 = 4.85) was slurried
up in the ammonium acetate solution at 75C. A mechanical
stirrer was fitted to the center hole of the flask, which
was also fitted with the necessary thermocouples and tempera-
ture controllers. Dropwise titration of the 3 liters of
(NH4)2SiF6 solution was begun at 75C. ~fter completion
of titration, which required a period of 2.5 hours, the pH
of the slurry was measured as 6Ø Overnight heating of
the mixture was conducted at 95C, the dropping funnel
having been replaced with a condenser. The stoichiometry
of the reaction was of the order of one Si added as (NH4)2SiF6
for every two Al atoms present in the zeolite. At the
conclusion of the reaction, the pH of the slurry was 6.75.
The reaction mixture was then filtered as two separate
batches and the solids washed with 18 liters of hot distilled
water. There was a residue of (NH4)3AlF6 present in the
washed materials. An additional wash of the products in
ammonium acetate was performed, followed by a thorough
wash with boiling distilled H20 until ~.u~litative tests
- 42 -
. .
12346-l
117~L837
could not detect either aluminum or fluoride ions in the
effluent wash water.
The properties of this material were as follows:
Chemical Analysis:
comPosition By Wei~ht-~/O: Molar Composition
Na20 0. 66 Na20/A1203 ~ 0. 08
(NH4~2 -6 . 50 (NH4) 20/A1203 ~ 0 . 91
A1203 ~13.97 Cation Equiva-
lent = 0.99
SiO2 - 78.55 Cation Defi-
ciencv = 1%
F - 0.02 F2/Al = 0.005
2 2 3 9 54
The product had the characteristic X-ray powder
diffraction pattern of zeolite LZ-210 and had a unit cell
dimension (aO) of 24.51 A. From peak intensity measure-
ments, the crystallinity of the product was 94 percent.
The water adsorption capac~ty at 25C and 4.6 Torr was
28,7 weight-%. The oxygen atsorption capacity at -183C
and 100 Torr oxygen pressure was 29.3 weight-%. The crystal-
collapse temperature of the product as measured by a stand-
ard DTA procedure was at 1061C. Untreated NH4Y using the
same DTA technique collap~es at 861C. The framework
infrared spectra of the starting zeol~te ant the protuct
zeolite are shown in Figure 1 of the trawings.
(b) Theprotuct of part (a) above was subjected to a
mild ion exchange treatment with NaCl solution to replace
most of the ammonium cations and then heated under vacuum
at 200C for 1 hour to remove adsorbed (molecular) water,
ant its hytroxyl infrared spectrum obtained. The spectrum,
~7~ 837 12346-l
denoted as "A" in Fi~ure 2, shows a small broad absorption
band with maximum absorbance at about 3300 cm l which is
attributed to the residual undecomposed ammonium cations,
two OH absorption bands at 3640 cm~l snd 3550 cm l
attributed to OH groups produced by the decomposition of
some of the residual ammonium cations, and a very small
broad absorption band due to the hydroxyl "nests" in vacant
framework sites in the zeolite. This absorption band is
best obser~ed in the region of about 3710 - 3715 cm 1 when
compared to the background absorption due to the zeolite.
Four hundred fifty gm of NaY containing 1.97 moles
of aluminum as A1203 were slurried in 8 liters of distilled
water with 287.7 gm of H4 EDTA (0.98 moles). The stirring
slurry was refluxed for 18 hours, filtered washed and
dried in air 2 hours at 110C. From the chemical analyses
the product, Labled Defect Structure Standard, Sample A,
was 48% depleted in aluminum. The calculated mole fraction
of defects in the structure of Defect Structure Standard,
Sample A,was 0.140. The framework composition expressed
in terms of tetrahedral mole fractions (T02) was:
(Alo 15osio~71 ~ .140) 2
Spectrum B of Figure 2 is the spectrum of Defect
Structure Standard, Sample A, from which 48% of the zeolite
framework aluminum has been removed by extraction with
H4 EDTA. The infrared sample was heated under vacuum at
200C for 1 hour to remove water. The spectrum shows the
expected broad absorption band due to hydroxyl nests in
vacant framework sites. In addition, there is a sharp
absorption band at 3745 cm 1 attributed to terminal -SiOH
groups in ~he zeolite structure as previously discussed.
12346-1
1~71~337
Similar bands are als~ observed with amorphous silica.
The spectra have been recorded in Figure 2 such that a
nearly quantitati~e comparison can be made between the
two samples. It becomes obvious then that the product of
the (NH4)2SiF6 treatment of NH4Y, from which 50~/0 of the
framework aluminum atoms have been removed, contains very
few residual vacancies or hydroxyl nests in the framework.
It is even further obvious that the silicon taken up bv
the zeolite during the (NH4)2SiF6 treatment must be substi-
tuted into the previously vacant framework sites. No
new absorption band at 3745 cm 1 due to amorphous -SiOH
is observed in this spectrum.
(c) The absolute absorbance of the Defect Structure
Standard, Sample A, measured at 3710 cm 1 as in Figure 2 was
0.330. The absolute absorbance of the LZ-210 product of
part (b) measured at 3710 cm 1 as in Figure 2 was 0.088.
The Defect Structure Factor, z, for the LZ-210 product was
calculated:
rAbsolute Absorbance ~f the Unknown~ ~ole fraction o~
(unknown Z)' ~easured at 3710 cm J X defects in the
¦standard
rAbsolutelAbsorbance of Standard measured at
3710 cm
:_
Substituting into the equation, the defect structure factor
for the LZ-210 product is 0.088 x 0.140; z = 0.037.
0.330
The framework composition of the LZ-210 product of
part (b) of this Example can be expressed:
(Alo 167Sio~79 ~0.037)2
The framework composition of the starting NH4Y, used to
prepare the LZ-210 product can be expressed
(Alo 292Sio. 70~10)o2
,
~7183'7 12346-1
Comparing the LZ-210 product with the NH4Y starting
material, the chan~e in Defect Structure Factor, ~z, is
0.037, well below the preferred maximum specification for
LZ-210 of 0.05. The mole fraction of aluminum removed from
the framework, N, is 0.125, which is substantially greater
than the minimum specification that N ~0.3a. The increased
silicon content of the framework of the LZ-210 product,
expressed as a function of the removed aluminum actually
replaced by silicon is:
-h-- ~ -125-0 037 0 70
Example 2
This example provides further proof that in the present
process aluminum is removed from the zeolite framework and
replaced in the framework by silicon from an extraneous
source. Two grams (anhydrous weight) of ammonium zeolite
Y (SiO2/A1203 molar ratio - 4.8) were slurried in 100 ml
of 3.4 molar ammonium acetate solution at 75C. The total
aluminum content of the zeolite sample was 8.90 millimoles.
A 50 ml solution containin~ 0.793 gm. (NH4)2SiF6 was added
to the stirring slurry of the zeolite in 2 ml increments
with 5 minutes between each addition. A total of 4.45
millimoles of Si was added to the zeolite. The mixture was
kept at 75C for 18 hours, filtered and washed. Analysis
of the filtrate and washin~s showed that of the 4.45
millimoles of silicon added, 3.4P. millimoles were consumed
by the zeolite during the reaction. At the sametime, the
zecl~te released 3.52 millimoles of aluminum to solution.
The molar SiO2/A1203 of the zeolite, based on the filtrate
analysis was calculated to be 9.30. Chemical analysis of
the solid product gave a SiO2/A1203 ratio of 9.31. These
data prove conclusively that as a result of our treatment
- 46 -
1171~7 12346-l
using buffered (NH4)2SiF6, silicon insertion had occurred.
From the peak intensity measurements, the product was
106 percent crystalline. The unit cell (aO) was 24.49 A.
The DTA exotherm denoting crystal collapse was found at
1037C. The intensity of the infrared OH absorption band
measured at 3710 cm l following activation of the zeolite
wafer at 200C attributable to (OH)4 ~roups in aluminum
depleted sites was very small, indicatin~ that very few
defect sites were present in the product. The oxygen
adsorption capacity of the product measured at -183C and
100 Torr was 25.8 weight percent.
Exam~le 3
To a reaction vessel provided with heating and
stirring means and containing 121.8 pounds (14.61 gal.)
of water and 18.5 pounds of ammonium acetate was added 30
pounds (anhydrous basis) of 80% ammonium exchanged zeolite
~aY having a Si02/A1203 ~olar ratio of 4.97. The resulting
slurry was heated to 75C. In a separate vessel an ammonium
fluorosilicate r(NH4)2SiF6 ,7 solution was prepared by
dissolving 12.25 pounds of the silicate in 46.8 pounds of
water at a temperature of 50C. By means of a metering
pump, the fluorosilicate solution was added to the buffered
zeolite slurry at the rate of 0.031 gallons per minute.
About 3 hours was required to complete the addition. At
the end of the addition period, the resultant mixture was
heated to 95C with continuous agitation for a period of
16 hours, filtered, and washed with about 250 gallons of
water at a temperature of 50C and dried. The product had
the following properties:
- 47 -
.
1~71~37 12346-1-c
(n) X-r~y cry6t~11inity (relative) ~ 90~.
(b) Tem~er~ture o~ cry~tal ~oll~pse (by DTA exotherm)
1110~C.
(c) Oxygen ~ds~rption capacity (-1839C, 100 torr)
26.1 wt.~.
(d) Water adsorption capacity (25C, 4.6 torr) ~ 24.5
wt .~
(e) SiO2/A1203 Qolar r~tio - 11.98.
(f) Zeolitic cation equivalence (~20/A1203)
1Ø
(9l Unit cell dimension, aO, ~ 24,~4 Angst~oms.
The framework composition of the starting NH4Y
expressed in terms of its molar fractions of tetrahedra can
be stated thusly:
(Alo 286Sio.714) 2
The Defect Structure Factor, z, for the L2-210 product
is 0.130. The framework composition of the LZ-210 product
can be expressed as:
[Al(a_N)S1b+(N_~3)C z]2
The change in the Detect Structure Factor, ~z, for the
LZ-210 is 0.055. The mole fraction of aluminum re~oved, N,
is 0.151 and the amount of removed aluminum replaced by
silicon is ~ O.64. All other characteristic
properties of the modified zeolite compositions of this
invention, i.e. X-ray powder diffraction pattern and
infrared spectra were exhibited by the product of this
example.
Example 4
(a) Forty-seven grams of NH4-Y containing 0.2065
moles of aluminum as A1203, were treated with ~NH4)2H2
EDTA and dilute HCl, sufficient to extract 43~ of the
- 48 -
12346-1
1~7~37
framework aluminum in the NH4Y, over a period of 4 days
in accordance with the tea.hir.gsand examplesofKerr in
U.S. Patent 4,093,560. This was labled Sample B.
(b) Two thousand five hundred grams of NH4Y were
stirred into 10 liters of 3.5 M ammonium acetate solution
at 75C. A 3.5 liter solution of water containing 990 gr,,.
(NH4)2SiF6 was heated to 75C and added in 100 ml. incre-
ments to the NH4Y slurry at the rate of 100 ml every 5
minutes. Following the addition of the fluorosilicate
solution, the temperature of the slurry was raised to
95C and the slurry was digested at 95C for 17 hours. The
digested slurry was filtered and the filter cake washed
until tests of the wash water were negative for aluminum
and fluoride ion. This was labled Sample C.
(c) The chemical and other analyses for the two
samples are set forth below together with similar tata
obtained on Defect Structure Standard, Sample A, prepared
in (b) of Example 1.
- 4~ -
~3l7~337
~ O ~ v w ~ x ~ ~ s~ r c ~ ~o
s' L- '~ 1
l \c~ V/ a~ v/ v~ ~ l v/ v ~n ~.
F ~ L ~ ~ ~- i 6 . L 3
~ ~ n O O ~ ~ ~ O O D 3
L L L 3- ~ L L
~r r~O ~ 0 ~
- 50 --
12346-1
1173 ~337
These data clearly distinguish the LZ-210 product
(Sample C) from the prior art product (Sample B). Both
Sample B and Sample C are aluminum depleted to ~he same
level as the reference Defect Structure Standard (Sample A).
The prior art product shows no evidence that silicon from
any source has substituted in the framework in place of
the aluminum. In fact, the prior art sample and the
reference Defect Structure Standard are nearly identical
in all of their pr~perties. The LZ-210 product shows
evidence of very little defect structure, indicating that
in this case silicon has replaced aluminum in the frame-
work.
Example 5
(A) One hundred grams of a well-crystallized zeolite
Y having a molar Si02/A1203 ratio of 3.50 was slurried with
500 ml, of a 4 molar aqueous NH4Cl solution at reflux for
one hour and then isolated by filtration. This exchange
procedure was repeated twice, and the product of the third
exchange washet with hot distillet water until tests of
the wash water were negative for chloride ions. Sixty
grams (anhydrous weight) of the NH4+ - exchanged product
were slurried in 400 ml. of 3.4 molar ammonium acetate
solution at 95C. A solution of 12.53 grams of ammonium
fluorosilicate in 150 ml. of water was added to the slurry
(pH 36) $n 1 ml. increments at the rate of 1 ml. per
minute. The stoichiometric ratio of moles of Si, added
as ammonium fluorosilicate ,to the moles of Al present
in the zeolite was 0.21. Following the addition of the
fluorosilicate solution, the slurry was digested for 3
hours at 95C., filtered, and the filter cake thoroughly
washed until tests of the wash water were negative for
-- 51 --
12346-1
~L~lL7~L837
aluminum and the flu~ride ion. The chemical and other
analyses for the starting NH4Y zeolite and the product
zeolite are set forth below:
N~4-Y Product
_ _ _ _
Na20 - wt.% 3.1 2.8
4 2 9.8 8.3
A123 wt. % 28.3 22.9
SiO2 wt.-% 58.2 65.2
SiO2/A1203 (molar) 3 50 4.84
Na tAl 0.18 0.20
~H4 /Al 0.68 0.71
Cation Equiv. (M /Al) 0.86 0.91
X-ray Crystallinity;
(a) By Peak Intensity lO0 98
(b) By Peak Area 100 97
Unit cell timension (aO)24.81 24.734
Framework Infrared;
Asymmetric Stretch, cm 1891 1003
Symmetric Stretch, cm 1 771 782
Hydroxyl Infrared;
Absolute Abs. at 3710 cm 1 0.039 0.058
Defect Stfucture Factor, z 0.016 ~.~2'
The framework mole fractions of tetrahedra are set forth
below for the starting NH4Y and the LZ-210 product.
a) ~5O1e fraction of oxides (T02) - (Alo.358sio.626 0.016)2
(Alo 2RsSio 690 0.025) 2
b) Mole fraction of aluminum removed, N - 0.073
c) % aluminum removed, n/a x 100 - 20
t) change in defect structure factor,~z - 0.009
e) moles of silicon substituted per
mole of aluminum removed,N-~z 0.88
_ ~, _
12346-1
1173 ~37
The analytical data show conslusively that framework
aluminum was removed and replaced by silicon as a res~lt
of the fluorosilicate treatment. The X-ray crystallinity
was fully maintained and the unit cell dimension decreased
as would be expected due to the smaller atomic size Df
silicon with respect to aluminum.
(B) The adverse effects of using a startin~ zeolite
having a molar Si02/Al203 ratio of less than 3 is demon-
strated by the following procedure:
One hundred grams of an ammonium-exchanged zeolite X
having a molar Si02/A1203 ratio of 2.52 were slurried in
1000 ml. of an aqueous 2.0 molar solution of ammonium
acetate at a temperature of 75C. Five hundred milli-
liters of a second aqueous solution containing 59.75 grams
of ammonium fluorosilicate was added to the slurry in
10 ml. increments st a rate of 10 ml. every 5 minutes.
The stoichiometric ratio of moles of silicon added to the
moles of aluminum present in the zeolite was 0.50. Follow-
ing the adtition of the fluorosilicate solution, the slurry
was digested for 16 hours at 95C, filtered, and washed
with distilled water until tests of the wash water were
negative for both aluminum and fluoride ions. The chemical
and other analyses for the starting NH4-X zeolite and the
product zeolite are set forth below:
- 53 -
1~7~837
NH4-X Product
Na20 - wt.~/o 3.2 0.5
(NH4)20 ~ wt.% 10.8 6.5
l2o3 wt.% 34.2 l9.t)
SiO2 - wt.% 50.8 72.0
SiO2/A1203 (molar) 2.52 6 . ~3
Na /Al 0.15 0.04
NH +/Al 0. 62 0 . 67
Cation Equivalent (M /Al) 0.77 0.71
X-ray Crystallinity;
(a) by Peak Intensity 100 clO
Unit cell dimension (aO),A.24.945 __
Framework Infrared:
(a) Asymmetric Stretch, cm l 987 1049
(b) Symmetric Srretch, cm 1 749 780
Hydroxyl Infrared;
Absolute Abs. at 3710 cm l0.110 U.224
Defect Structure Factor, z 0.047 0.095
It is apparent from the foregoing data that although
dealumination in conjunction with silicon substitution
into the zeolite framework did occur, the procedure was
highly destructive of the crystallinity of the product
zeolite. Also the remaining crystal structure contained
an undue number of defect site.
(C) In a second attempt to treat the NH4-X of part
(B), a 5 gram sample of the zeolite was slurried in 100
ml. of a 3.4 molar ammonium acetate solution at 95C.
Fifty milliliters of a second aqueous solution containing
1.49 grams of ammonium fluorosilicate was added to the
slurry in 2 ml. incremen~s at a rate of 2 ml. every five
minutes. The stoichiometric ratio of moles of silicon
- 54 -
12346-l
1171837
added to the moles of zeolitic aluminum was 0.25. Follo~-
ing the completion ofthe addition of the fluorosilicate
solution, the slurry was digested for 3 hours, filtered
and washed. Although the treatment of this part (C) was
much less rigorous than that of part (B) above by v~reue
of increased buffering, lower fluorosilicate concentration
and shorter digestion time, the product of part (C) was
found to be nearly amorphous.
Example 6
~ he process for substituting extraneous silicon for
framework aluminum atoms in a zeolite having the zeoli~e
A-type structure is illustrated by the following experi-
mental procedure: Approximately S grams of zeolite N-A
(prepared hydrothermally using a combination of sodium
hydroxide and tetramethylammonium hydroxide in accordance
with the teachings of U.S.P. 3,305,922) having a SiO2/
A1203 molar ratio of 6.0 was calcined in air at 550C
for 17 hours to remove the tetramethylammonlum cations.
The resulting decationized form of the zeolite was ion-
exchanged with an aqueous solution of NH4Cl. A twelve
gram (anhyd.) sample of the resulting NH4-A zeolite was
slurried ~n 300 ml. of an aqueous 3.4 molar ammonium
acetate solution at 75C and 100 ml. of an aqueous solution
containing 4.63 gm. ammonium fluorosilicate was added
thereto in 1 ml. increments at the rate of l ml. per
minute. Following completionof the addition of the fluoro-
silicate solution, the slurry was digested for 16 hours
at 75C filtered, and the solids then tho,oughly
washed with water. The preliminary decationization and
12346-1
1~ 7~837
subsequent rehydration of the starting zeolite introduced
a considerable number of defect sites into the zeolite
starting material which were not, under the conditions
employed in the fluorosilicate treatment, filled by silicon
insertion. The observed decrease in the unit cell dimension,
aO, from 11.994 to 11.970, however, establishes that
extraneous silicon from the fluorosilicate was substituted
for original framework aluminum atoms in the zeolite. The
results of chemical and other analyses for the starting
NH4-NA and the LZ-215 product zeolite are set forth below:
NH4-NA LZ-215 Product
Si02/A1203 (molar) 5-43 7.38
Cation Equivalent, (M /Al) 0.65 0.69
X-Ray Crystallinity: .
(a) % by Peak Intensity 100 60
(b) % by Peak Area 100 59
Unit Cell Dimension (aO) 11.994 11.970
Framework Infrared:
asymmetric Stretch, cm 1 1062 1069
symmetric Stretch, cm 1 713 722
Hydroxyl Infrared:
Defect Structure Factor (z)0.042 0.079
Absolute Absorbance at 3710 cm~l 0.100 0.186
The framework mole fractions of tetrahedra are set forth
below for the starting NH4-NA and the LZ-215 product.
a) Mole fraction of oxides (T02) - (Alo 2S8Sio 700r~o 042)2
(Alo 196sio.725 0.079)2
b) Mole fraction of aluminum removed,N - 0.062
c) % aluminum removed, N/a x 100 - 24
d) Change in defect structure factor , ~z,- 0.037
e) Moles of silicon substituted per mole
of aluminum removed, (~-~z)/N _ 0.40
12346-1-C
~171837
In order to prepare a high silica zeolite of the
type-A structure which is substantially free of defect
sites it is necessary either to maintain the organic
cations in the starting zeolite or to thermally degrade
the organic cations to NH4+ or H+ cations under controlled
conditions such as minimal decomposition temperatures and
in an environment of nitrogen and/or ammonia.
Example 7
(A) The substitution of extraneous silicon into the
crystal lattice of a zeolite of the mordenite type is
illustrated by this example in which a commercially avail-
able synthetic acid-treated mordenite was used as the
starting material. One thousand grams of the synthetic
mordenite (SiO2/A1203 = 11.67) were slurried in 8 liters
of distilled water at reflux temperature. Three liters
of an aqueous solution containlng 435 grams of ammonium
fluorosilicate was added rapidly to the zeolite-water
slurry and the resultant mixture refluxed with stirring
for 96 hours. The zeolite product was then isolated by
filtration and washed with distilled water. The chemical
and other analyses results are set forth below for the
starting material and the product zeolite.
B
12346-l
1~7~837
H-Zeolon LZ-211
_ Product
Na20, wt.-% 0.48 0.32
(NH4)20, wt.-% __ 1.65
A1203, wt.-% 12.44 6.48
SiO2, wt.-% 85.51 91.88
SiO2/Al203(molar) 11.6' 24.08
Na /Al 0.05 0.08
N~4 /Al __ 0 50
Cation Equivalent, M /Al 0.06 0.58
X ray Crystallinity by
Peak Intensity 100 85
Fra~ework Infrared:
Asymmetric Stretch, cmll 1070 1093
Symmetric Stretch, cm 801 811
Hydroxyl Infrared:
Absolute Abs. at 3710 cm 0.185 0.245
Defect Structure Factor, z 0.078 0.104
Since the starting H-2eolon contained a substantial
number of defect sites, it is not necessary that the process
substitute silicon into those tefect sites. The fact that
the process of this invention does not create any substan-
tial amount of new defects in the structure is substantiated
by the fact that the Defect Structure Factor, "z", increased
by only 0.026 as a result of the treatment.
The framework mole fractions of tetrahedra are shown
below for the starting H-Zeolon and the LZ-211 Product.
a) Mole fraction of oxides ~TO2) H-Zeolon - (Alo.l34si0.787r0.078 2
LZ-211 - (Alo 069Sio,827 0~lo4~o2
b) Mole fraction of aluminum removed, N - 0.065
c) % Aluminum Removed, N/a x 100 - 49
- 58 -
12346-l
13L7~L~337
d) Change in Defect Structure Factor,~z - 0.026
e) Moles of silicon substituted per mole
of aluminum removed, N-~z - 0.60
N
These data show quite conclusively that aluminum has
been removed from the structure and replaced with ~ilicon
as a result of the fluorosilicate treatment. It is also
apparent that the treatment conditions, particularly the
rapid addition of the fluorosilicate solution to the zeolite,
did not permit the insertion of silicon into all of the
sites from which aluminum was removed during the treatment
or into all of the aluminum depleted sites of the original
H-Zeolon starting material. On the other hand, X-ray
crystallinity was maintained, and while no exotherm due to
crystal collapse was observed in either sample in differen-
tial thermal analyses, sintering began at about 1000C in
the starting zeolite but did not occur ùntil about 1150C
in the product zeolite. The framework infrared spectra
show shifts to higher wavenumbers following fluorosilicate
treatment. The shift of both the asymmetric stretch band
and the symmet~ic stretch band is characteristic of dealumina-
tion accompan$ed by silicon substitution in the framework.
In the hydroxyl region of the infrared spectrum of the
fluorosilicate treated zeolite there was no increase in
the 3745 cm 1 band tue to occluded amorphous Si~H. There
was only a small increase in absorbance at 3710 cm 1 compared
to the starting H-Zeolon indicating that there was only a
small increase in the number of framework vacancies due to
the treatment. It is to be noted, however, that moderating
the severity of the treatment as illustrated in part (B)
of the Example, below, results not only in the substantial
replacement of aluminum atoms removed during the treatment,
but also considerable filling of aluminum-vacant sites in
- 59 -
. . .
.
~7~.~337 12346 l
the starting zeolite.
(B) In another example, 2500 grams of a similar H-
Zeolon starting materi~l as employed in part (A) was
stirred in 5 liters of distilled water at 95C. A second
solution of 5 liters of distilled water containing 3B2.7
grams of ammonium fluorosilicate at a temperature of about
75C was added directiy to the zeolite-water slurry at a
rate of about 50-100 ml. per minute. During the addition
period the temperature was maintained at 95C. The stoi-
chiometric ratio of moles of silicon added to the moles of
aluminum present in the zeolite was 0.41. Follow comple-
tion of the addition ofthe fluorosilicate solution, the
slurry was digested for 72 hours under reflux conditions,
the solids recovered by filtration, and washed with distilled
water. The chemical and other analyses results are set
iorth below: LZ-211
H-Zeolon _ Prod~ct
Na20, wt.-% 0.2 0.2
(L~H4)20, wt,-% __ 2.1
A1203, wt.-% 10.8 5.7
SiO2, wt.-% 88.8 9~.4
S~02/A1203 (molar~ 14.00 24.12
~a /Al .0 03 0,04
~H4 /Al -- 0.72
Cation Eauivalent, M /Al 0.03 .~0.76
X-ray Crystallinity:
ta) by Peak Intensity 100 86
(b) by Peak Area 100 90
Fra~ework Infrared:
Asymmetric Stretch, cm 1 1073 1089
Symmetric Stretch, cm 1 801 815
Hydroxyl Infraret:
Absolute Abs. at 3710 cm 1 0.325 0.115
Defect Structure Factor, z 0.137 0.048
- 63 -
12346-1
1~71837
In this example, the defect structure factor of
the starting H-Zeolon is quite large. As a resul~ of
the treatment it would appear that a substantial number
of the ori~inal defect sites have been eliminated. The
framework mole fractions are set forth below for the start-
ing H-Ze~lon and the LZ-211 product
a) Mole fraction of oxides(TO~ H-Zeolon (Alo 108Sio 755r-0 137)
LZ-211 (Alo 073SiO.879 0.048)
b) Mole fraction of aluminum removed,~l - o.n35
c) % Aluminum tepletion, N/a x 100 - 32
c) Change in defect structure,~ z - -O.089
From the data it is apparent that silicon atoms
were substituted for aluminum atoms in the Zeolon struc-
ture. The framework infrared spectra show shifts to higher
wavenumbers following the fluorosilicate treatment. The
shift of both the asymmetric stretch band and the symmetric
stretch band is characteristic of dealumination accompanied
by s~licon substitution in the framework. In the hydroxyl
region of the infrared spectrum, the fluorosilicate treated
sample shows no increase in absorbance at 3745 cm 1 due to
occluted SiOH species. There was a substantial decrease in
absorbance at 3710 cm 1 compared to the starting H-Zeolon
indicating that there was a decrease in the number of
framework vacancies or defect sites.
(C) To gain insight into the silicon substitution
mechanism occurring during the treatment procedure in
part.(B) above, samples of the H-Zeolon were taken
periodically during the course o. treatment and analyzed.
- 6, -
12346-1
1 ~ 71 ~ 37
The results are shown below:
Start of End of After 24 After 4B After 72
~dditia~ Addieian h~rs of ha~s of hours of
of Amnoni- of AmnD- digestion digestion digestion
un flwr~ ni~n~ n,.~-
sillcate rosilicate
X-ray Crystallinity:
(~) by Peak Inten~ity 100 121 107 97 ~6
(b) by Peak Area 100 117 106 99 90
Framew~rk Infrared:
Asymmetric Stretch,
cm-l 1073 1~85 1088 1085 1089
Symcetric Stretch
cm-l ' 801 813 814 815 815
Hydroxyl Infrared;
~bsolute Abs. at
3710 cm-l 0.325 ~.180 0.160 0.130 0.115
Defect Structure
Factor, z 0.137 O.076 O.068 O.055 O.048
From the foregoing, it is apparent that a considerable
amount of silicon substitution had taken place by the
end of the fluorosilicate addition period.
Example 8
Fluorosilicate Treatment of Mordenite, (a natural
ore from Union Pass, Nevada, U.S.A.).
One thousand gm (anhydrous weight) of a ground natural
mordenite ore was added to 10 liters of l.ON HCl solution
in a 22 liter flask heated at 95C. The slurry was stirred
for one hour at 95C, filtered and rinsed with 10 liters
of distilled water. The acid exchange procedure was re-
peated twice more then the solids were washed with distilled
water until the wash water remained clear when tested for
the presence of chloride with AgNO3 solution.
(a) Five hundred gm of the H+ mordenite was slurried
in 2 liters of distilled water at 75C. A second solution
of 1.5 liters of distilled water containing 100.12 gm AFS
was added in a continuous manner to the zeolite slurry at
a rate of lO ml./min. The stoichiometric ratio of moles
of Si added as AFS to the moles of Al present
- 62 -
~i~
12346-1
13L71~337
in the zeolite was 0.50. Followin~, the addition of the
fluorosilicate solution the slurry was digested for 26
hours under reflux conditions, then fileered and thorou~hly
washed until tests of the wash water proved negative for
both aluminum and fluoride ions. The chemical analyses
of the starting H mordenite and the product of the fluoro-
silicate treatment are shown in Table 6A.
TABLE 6A
S$artin~ T~eated
H Mordenite H Mordenite
Na20, wt.% 0.29 0.22
(NH4)20, wt.% 1.4j
A1203, wt.% 11.46 8.18
SiO2, wt.% 83.56 85.31
F2, wt.% - 2.35
SiO2/A1203 12.37 17.68
Na /Al 0.04 0 04
NH4 /Al _ 0.71
Cation Eguivalent, M /Al 0.48 0.79
A comparison of the properties of the treated zeolite with
the starting material is shown in Table 6B.
TABLE 6B
Starting H+ Treated H+
Mordenite Mordenite
.
Chemical SiO2/A1203 12.37 17.68
Chemical M+/Al 0.48 0.79
X-Ray Crystallinity
(I) By Peak Intensity 100 89
(II) By Peak Area 100 75
Crystal Collapse Temp.,C(DTA) ~ 1025 No Exotherm
Framework Infrared
Asymmetric Stretch, cm 1 1085 1098
~71B37 12346-l
TA~LE 6R continued
Starting H Treated H
Mordenite Mordenite
Symmetric Stretch, cm 1 792 794
Hydroxyl lnfrared
Absolute Absorbance at 3710 cm 1 0.225 0.310
The mole fractions of framework tetrahedra (TO2) sre set
forth below in Table 6C for the startin~ H~-mordenite and
the LZ-211 product.
TABLE 6C
a) Mole fraction of oxides ~O~; H -Mordenite - (Alo 1~6Sio 779 0 095~
LZ-211 Product- (Al~ 0885io.781 0.131)(
b) Mole fraction of aluminum removed; N - 0.038
c) % aluminum removet, N/a x 100 - 30
c) Change in defect structure factor, ~z - 0.036
e) Moles of silicon substitutet per mole
of aluminum removet,~N-4z )/N - 0.05
The analytical tata in this case to not conclusively
demonstrate that silicon has replaced aluminum in the
mordenite framework although the X-ray crystallinity is
maintainet. However, because of the particle size of the
mordenite crystals unter stuty, it is tifficult to obtain
a high degree of infraret transmission throu~h the zeolite
wafer. The absorption bants in the framework infraret
region are broader and less well definet than for instance
with H-Zeolon. Nevertheless, it is obvious that the amount
of shift of the asymmetric stretch band is substantially
greater than the symmetric stretch bant shift. This is
characteristic of a zeolite framework that has been dealu-
minated with little or no silicon substitution in the
vacant sites. However, the infrared spectrum of the hydroxyl
region of the fluorosilicate treated sample did not show
- 64 -
12346-1
1~71837
anv increased absorbance at 3745 cm 1 due to SiOH species
The increase in absorbance at 3?10 cm 1 due to hydrogen
bonded OH groups in vacant sites did not increase commen-
surate with amount of aluminum removed during the treat-
ment.
(b) A second sample of H+-mordenite weighin~ 317 gm
(anhydrous wei~ht) was slurried in 2 liters of distilled
water at 75C. A se.ond so~ution of 1.5 liters distilled
water containing 126.87 ~m (NH4)2SiF6 was added in a con-
tinuous manner to the zeolite slurry at a rate of 10 ml
per minute. The stoichiometric ratio of moles of Si
added as [(NH4)2SiE6] to the moles o' ~1 ~resent in the
zeolite was 1.00. Following the addition of the fluoro-
silicate solution, the slurry was digested for 48 hours
under reflux conditions then filtered and thoroughly washed
until te~ts of the wash water proved negative for both
aluminum and fluoride ions. The chemical analyses of the
starting H+ mordenite and the product of the fluorosilicate
treatment are shown in Table 7A, below:
TABLE 7A
Starting H+Treated H
MordeniteMordenite
Na20, wt.% 0.29 0.22
(NH4)20, wt.% _ 1.35
A1203, wt.% 11.46 7.29
SiO2, wt.% 83.56 86.77
F2, wt.% - 3.36
SiO2/A1203 12.37 12.20
Na+/Al 0 04 0.05
NH4 /Al - 0.36
Cation Equivalent, M /Al 0.48 ~0.80
12346-1
~17~837
A comparison of the properties of the treated ze~lite
with the starting H+ mordenite is shown in Table 7B, below:
TABLE 7B
Starting H Treated H
Mordenite Mordenite
Chemical Si02/A1203 1?.. 37 20.20
Chemical M /Al 0 . 48 0 . 81
X-Ray Crystallinity
(I) By Peak Intensity 100 120
(II) By Peak Area 100 102
Crystal Collapse Temp. C(DTA) 1025 .lo Exother~
Framework Infrared
Asymmetric Stretch, cm 1085 NA
Symmetric Stretch, cm 1 792 NA
Hydroxyl Infrared
Absolute Absorbance at 3710 cm 1 0.225 0.300
The mole fractions of framework tetrahedra (TO2) are set
forth for the starting H+-mordenite and the LZ-211 product
in Table 7C below:
TABLE 7C
a) Mole fraction of Oxides,(TO2) H+-mordenite (Alo 126Sio 779r0 095)0;
LZ-711 (Alo 07~ b.794 0.127)o2
b) Mole fraction of aluminum removed, Ni - 0.047
c) % FraMework aluminum removed, N/a x 100 - 37
t) Change in defect structure factor, ~z - 0.032
e) Moles of silicon substituted per mole of
aluminum removed,(N-~ztN) - O.32
As in the case of the preceding Example, proof of
silicon substitution rests primarily on chemical analysis
and absolute absorbance measurements in the hydroxyl
stretching region of the infrared spectrum ( 3710 cm 1).
- 65 -
.
~7:~337 l2346-l
The X-ray crystallinity was maintained. The peak area
measurement shows the same value as the starting H~-
mordenite and the peak intensity measurement indicates
an increase in intensity due to peak sharpening. This
suggests a more ordered structure than ~he starting H+-
mordenite, the exact nature of which is not known at this
time. The calculated unit cell ~alues make it quite certain
that a substantial amount of silicon has replaced alu~inum
in the framework. This alone could be the cause of increased
intensity measurements in the X-ray powder pattern. A
sample taken after 24 hours of the fluorosilicate treatment
had a SiO2/Al203 ratio of 19.1, a fluoride content of 3.5
wt.~/, and absolute absorbance at 3710 cm l of 0.330. Com-
paring this sample to the sample described in Tables 6A,
B and C, supra increasing the amount of fluorosilicate in
the treatment step increases the amount of silicon substi-
tution. Increasing the tigestion time also increased the
degree of silicon substitution. It is apparently more
difficult to substitute silicon into the framework structure
of natural mortenite than it is to substitute it into the
framework of synthetic mordenite.
Example 9
Fluorosilicate Treatment of NH4~-L Zeolite to Produce
L7-212.
(a) Fifty gm of NaKL zeolite (SiO2/A1203 molar ratio
of 6.03) was slurried with 500 ml of 1.0 molar NH4Cl solution
at reflux for 16 hours and filtered. The exchange was
repeated three times more and the product of the third
exchange was washed with hot distilled water until tests
of the wash water were negative when tested for chloride
with AgNO3 solution From the product lO.0 gm (anhydrous
~7~837 12346-1
weight) was slurried in 100 ml of distilled water heated
at 75C. A second solution of 50 ml containing 3.36 gm
(NH4)2SiF6 was added to the NH4L-water slurry in 1 ml
increments at a rate of 1 ml every five minutes. During
the course of the fluorosilicate addition the temperature
was maintained at 75C. The stoichiometric ratio of moles
of Si added ~s [(~H4` -~iF~, to the mo1es of Al ~resent i~ the
zèolite was 0.50. Following addition of the fluorosilicate
solution the slurry was heated to 95C for 16 hours, then
filtered and thoroughly washed until tests of the wash
water proved negative for both aluminum and fluoride ions.
The chemical analyses for the starting NH4L and the
product of the fluorosilicate treatment are shown in Table
8A, below:
TABLE 8A
Starting NH4L LZ-212 Product
~2~ wt,% 3.43 2.03
(NH4)20, wt,% 8.35 3.46
A1203, wt,% 19.22 11.15
SiO2,wt,% 68.31 81.38
F2, wt,% - 0,04
SiO2/A1203 6,03 12.39
K+/Al 0.19 0.47
NH4 /A1 0.85 0.61
Cation Equivalent, M /A1 1.04 1.08
A co~parison of the properties of the treated zeolite with
the starting material is shown in Table 8B.
- 68 -
117~837 12346-1-C
TAaLE 8B
Bt~rting NH4L LZ-212 Pro~uct
Chemic~l SiO2/A1203 6.03 12.3
Chemical M+/Al 1.05 1.0
X-RAy Cryst~llinity
(I) By Peak Inte~sity 100 Excellent
~II) By Peak AleaNA NA
Cryst~1 Coll~pse Temp., C (DTA)900 950
Framework In~r~red
~symmetric Stretch, cm 11028 1109
Sy~m~tric Stretch, cm 1 769 782
Hydroxyl Infrared
Absolute Ads~rb~nce at 3170 cm 1 0.085 0.1Y5
The frame work mole fractions are set forth in Table 8C
below for the starting NH4L and the LZ-212 product.
TA~LE ~C
a) Mole fraction of oxides ~TO2);
~L - (Alo.o24slo.724 oo.o36)o2
LZ-212 ~Alo, 128Slo. 790 C.082)02
b) Mole fraction of aluminum removed, N: - 0.112
c) Percent of framework aluminum removed, N/a x 100 - 47
d) Change in defect structure factor, ~z - 0.046
e) Moles of silicon substituted per mole of
aluminum removed, (N- ~z)/N -0.57
The data show quite conclusively that under the
conditions given, silicon substitutes for aluminum in the L
zeolite framework with a high degree of efficiency. X-ray
crystallinity is maintained and the thermal stability is
apparently increased. More im~ortantly, both the
asymmetric stretch ~and and the symmetric stretch band in
the framework infrared spectra increase following the
treatment. This is a consistent with dealumination
- 69 -
,
12346-1
13~7~837
accompanied by silicon substitution in the framework. ~o
absorption was observed at 3745 cm 1 due to
occluded SiOH species and there is only a small increas~
in absolute absorbance at 3710 cm 1 which reflects the
relative amount of hydrogen bonded OH groups in framework
vacancies. Dealumination was nearly stoichiometric with
the amount of fluorosilicate added.
(b) In a second experiment a fresh sample of NaY~L was
obtained. Three hundred and seventy-two gm of NaKL zeolite
(Si02/A1203 molar ratio of 5.93) was slurried with 1000
ml of 6 molar NH4Cl solution at reflux for 16 hours and
filtered. The exchange was repeated twice more and the
product of the third exchange was washed with hot distilled
water until tests of the wash water were negative when
testet for chloride with AgNO3 solution.
From the ammonium-exchanged product 10C gh (anhydrous
weight) was slurried in 300 ml of distilled water heated
at 75C. A second solution of 300 ml containing 33.94
~m (NH4)2SiF6 was added to the NH4L-water slurry in 10
ml increments at a rate of 10 ml every five minutes.
During the course of the fluorosilicate addition the
temperature was maintained at 75C. The stoichiometric
ratio of moles of Si added as ['N~L)2';_r~ to the ~.oles of
Al present in the zeolite was 0.50. Following addition of
the fluorosilicate solution the slurry was maintained at
75C and digested for 24 hours, then filtered and thoroughly
washed until tests of the wash water proved negative for
both aluminum and fluoride ions. The chemical analyses
for the starting NH4L and the product of the fluorosilicate
treatment are shown in Table 9A.
_ 7n _
12346-l
1~71837
TABLE 9A
Startin~ NH4L LZ-212
K20, wt.% 3.51 2.66
(NH4)20, wt % 7.89 4.10
A1203, wt.% 19.42 11.52
SiO2, wt.% 67.80 ~9.62
F2, wt.~/o - 0.08
SiO2/Al203 5.92 11.73
K /Al 0.20 0.25
NH4 /Al 0.80 0.70
Cation Equivalent, M /Al1.00 0.95
A comparison of the properties of the treated zeolite with
the starting NH4L is shown in Table 9B.
TABLE 9B
Starting NH4L LZ-212
Chemical SiO2/A1203 5.92 11.73
Chemical M /Al 1.00 0.95
X-2ay Crystallinity
(I) By Peak Intensity 100 49
(II) By Peak Area 100 52
Crystal Collapse Tem.,C(DTA) 995 940,
Framework Infrared
Asymmetric Stretch, cm 1 1028 1108, 1031
Symmetric Stretch, cm 1 768 780
Hydroxyl Infrared
Absolute Absorbance at 3710 cm 1 0.048 0.240
The framework mole fractions are set forth below in Table
9C for the starting NH4L and the LZ-212 product.
- 71 -
. . .
1~7~837 12346-1
TABLE 9C
a) Mole fraction of oxides (T02):
NH4L - (Alo 247Sio.733 0.020)2
LZ-212 - (Alo 13lSio 767 0.102~2
b) Mole fraction of aluminum removed, N; - 0.116
c) Percent of fra~eworK aluminum removed, N/a
x lO0 _ 47
d~ Change in defect structure factor,~ z - 0.082
e) Moles of silic~n substituted per mole of
aluminum removed, (N-~z)/N _ 0.29
It should be noted that the fluorosilicate digestion
temperature in the present example was 75C while that
in the previous example was at reflux. The degree of
tealumination is the same for both digestion temperatures
while the efficiency of silicon substitution is substan-
tially retuced at the lower dlgestion temperature.
Example_lO
Fluorosilicate Treatment of Clinoptilolite to Produce
LZ-219.
Twenty-five gm. of the natural mineral clinoptilolite
(SiO2/A1203 molar ratio of lO.3) was slurried with 200 ml.
of l M. NH4Cl solution at reflux for one hour and filtered.
The exchange was repeated twice more and the product of
the third exchange was washed with hot distilled water
until tests of the wash water showed negative for chloride.
From the ammonium-exchanged product, 5.~ gm (anhydrous
weight) was slurried in lO0 ml of distilled water heated
at 95C. A second solution of 50 ml containing 1.17 gm
(NH4)2SiF6 was added to the slurry in 2 ml increments at
a rate of 2 ml. per 5 minutes. The stochiometrLc ratio of
moles of Si added as [ (NH4)2SiF6] to the moles of Al
in the zeolite was 0.5. Following the addit.on o' the
fluorosilicate solution the slurry was digested for
7~
12346-1
1~71837
three hours at 95C then thorou~hly washed until tests of
the wash water proved ne~ative for both aluminum and flu~rid~
ions. The chemical analyses for the startin~ NH~ Clinopti-
lolite and the product of the fluorosilicate treatment ar~
sho~ in Table lOA, below:
TABLE lOA
Starting NH4 Product
Clinoptilollte
Na20, wt.~/o 0.55 0.66
(NH4)20, wt.% 5.19 3.85
A123' wt.% 12.82 11.33
SiO2, wt.c 77.90 81.41
F2, wt.~/c - 0.53
SiO2/A1203 10.31 12.20
i~a+/Al 0.07 0.10
NH4 /Al 0.79 0.67
Cation Equivalent, M+/Al0.93 0.82
A comparison of the properties of the treated zeolite with
the starting material is shown in Table lOB, below:
TABLE lOB
Starting NH Treated NH
Clinoptilol~te ClinoPtilo~ite
Chemical SiO2/A1203 10.31 12.20
Chemical I~+/Al 0.93 0.83
X-Ray Crystallinity
(I) By Peak Intensity 100 60
(II) By Peak Area 100 60
Crystal Collapse Temp.,C(DTA) 530 533
Framework Infrared
Asymmetric Stretch, cm 1 1062 1086
Symmetric Stretch, cm 1 795, 778 796, 778
Hydroxyl Infrared
Absolute Absorbance at 3710 cm 1 0.055 0.135
- 73 -
.. . . .
12346-1
117~B37
The framework mole fractions are set forth in Table lOC
below for the starting NH4-Clinoptilolite and the product.
TABLE lOC
a) ~Iole fraction of oxides (T02); NH4 Clino.- -I
(Alo 159sio.81~~~.023)2
Product
(Alo l33Sio.810 0.057)2
b) Mole fraction of aluminum removed, N; - 0.026
c) % of framework aluminum removed; N/a x lO0 - 16
d) Change in defect structure factor, ~z - 0.034
From the data it would appear that rnainly dealumination
resulted from the treatment of NH4 Clinoptilolite with the
(NH4)2SiF6 at 95C. However the efficiency of dealumination
i9 low, indicating that the sites in the framework where
the aluminum atoms are located are relatively inaccessible,
or that aluminum atoms in the particula~ environment of the
clinop~ilolite framework are extremely stable. Accordingly
when the experiment is repeated using more rigorous condi-
tions, preferred LZ-21~ products within the scope of the
preferred co~positions cc tho present invention are formed.
Exam~le 11
Fluorosilicate Treatment of Chabazite to Produce LZ-218
Twenty-five grams of the natural mineral chabazite
(SiO2/A1203 molar ratio of 8.5) was slurried with 200 ml
of 2 molar NH4Cl solution at-refluY. for one hour and
filtered. The exchange was repeated twice more and the
product of the third exchange was washed with hot distilled
ater until tests of the wash water showed negative for
chloride.
12346-1
1~7~33~7
From the ammonium exchanged prod~ct, 5.0 gm (anhydr~us
weight) was slurried in 100 ml of distilled water heated
at 95C. A second solution of 50 ml containing 2.60 ~m
(NH4)2SiF6 was added to the slurry in 2 ml increments at
a rate of 2 ml per five minutes. The stoichiometric ratio
of moles of silicon added as l(N~.4)~Si~6] to the moles of
aluminum present in the zeolite was 1.00. Following the
addition of the fluorosilciate solution the slurry was
digested for three hours at 95C then thoroughly washed
until tests of the wash water proved negative for both
aluminum and fluoride ions. The chemical analyses for tne
starting NH4 chabazite and the product of the fluorosilicat~
treatment are shown in Table llA, below:
TABLE llA
Starting NH4- LZ-218
Chabazite Product
Na20, wt.% NA 0.85
(NH4~20, wt.% 4.98 3.30
A1203, wt.% 14.83 12 05
SiO2, wt.% 74.51 78.98
F2, wt.% NA 0.39
SiO2/A1203 8.52 11.13
Na tAl NA 0.12
NH4 /Al 0.66 0.54
Cation Equivalent, M /Al 0.66 0.94
A comparison of the properties of the treated zeolite with
the starting material is shown in Table llB, below:
- 75 -
12346-1
117~837
TABLE llB
Starting NH4 LZ-218
Chabazite Product
Chemical SiO2/A1203 8.52 11.13
Chemical M /Al 0.69 0.94
X-Ray Crystallinity
(I) By Peak Intensity 100 164
(II) By Peak Area 100 106
Crystal Collapse Temp.,C(DTA) Sinter 940C Exotherm 930C
Framework Infrared
Asymmetric Stretch, cm 1 1042 1096
Symmetric Stretch, cm 1 771 785
Hydroxyl Infrared
Absolute Absorbance at 3710 cm 1 0.0750.145
The framework mole fractions are set forth in Table llC
below for the starting NH4 chabazite and the LZ-218 products
TABLE llC
a~ Mole fraction of framework oxides (T02); NH4 Chabazite -
(Alo 184sio.784 0.032)2
LZ-218
(Alo 143Sio.7gs 0.062)2
b) Mole fraction of aluminum removed, N- 0.041
c) % framework aluminum removed; N/a x 100 - 22
t) Change in defect structure factor , ~z, - 0.030
e) Moles of silicon substituted per mole of
aluminum removed; (N-4z)/N - 0.27
The data indicate that silicon has replaced aluminum in
the chabazite framework. The efficiency of aluminum removal
is relatively low compared with the Y, L and mordenite
zeolites, and comparable to that observed in the case of
clinoptilolite. However with chabazite, silicon does replace
the removed aluminum in the framework as shown by the shift
- 76 -
- 12346-1
1~7~837
of both the asymmetric stretch band and the symmetric stretch
band of the framework infrared spectrum to higher wavenumbers
Additionally, no evidence was found to indicate occlusion
of amorphous SiOH species which would account for the
increased silicon content in the zeolite. The increase
in X-ray peak intensity while the peak area remains constant
is taken as further evidence of silicon substitution in
the framework.
Example 12
Fluorosilicate Treatment of Erionite to Produce LZ-
220.
A 5.0 gm (anhydrous weight) sample of an ammonium
exchanged natural erionite was slurried in lOOml. of
distilled water heated at 95C. A second solution of
50 ml containing 1.60 gm (NH4)2SiF6 was added to the
slurry in 2 ml increments at a rate of 2 ml per minute.
The stoichiometric ratio of moles of Si added as ~N~14)~51P6]
to the ~oles of Al present in the zeolite was 0.54.
Following the addition of the fluorosilicate solution the
slurry was tigested for three hours at 95C then thoroughly
washed until tests of the wash water proved negative for
both aluminum and fluoride ions. The chemical analyses
for the starting NH4 Erionite and the product of the
fluorosilicate treatment are shown in Table 12A, below:
TABLE 12A
Starting NH4 Product
Erionite LZ-220
Na20, wt.% 0.35 0.24
(NH4)20, wt.% 5.75 3.54
A1203, wt.% 16.80 13.24
SiO2, wt.% 68.93 76.26
F2, Wt.% - 0.39
- 77 -
.
12346-1
1~71837
TABLE 12A ¢ontinued)
Starting NH4Product
Erionite LZ-~'J
SiO2/A1203 6.96 9.77
Na /Al 0.03 0,03
1 0.67 0.52
Cation Equivalent, M /Al 0.91 0.79
A comparison of the properties of the treated zeolite
with the starting material is shown in Table 12B, below:
TABLE 12B
Starting NH4Product
Erionite LZ-220
Chemical SiO2/A1203 6.96 9.77
Chemical M /Al 0.91 0.79
X-Ray Crystallinity
(I) By Peak Intensity 100 172
(Il) By Peak Area 100 150
Crystal Collapse Temp.,C(DTA) 976 995
Framework Infrared
Asymmetric Stretch, cm 1 1052 1081
Symmetric Stretch, cm 1 781 784
Hydroxyl Infrared
Absolute Absorbance at 3710 cm 1 0 0700.160
The framework mole fractions are set forth in Table 12C
below for the starting NH4-Erionite and the product zeolite.
TABLE 12C
a) Mole fraction of framework oxides, (T02);
NH4 Erionite - (Alo 217Sio,753 0 030)2
Product LZ-22~ ~Alo 158sio.774 0.068)2
b) Mole fraction of aluminum removed, N - 0.059
c) % of framework aluminum removed, N/a x 100 - 27
- 78 -
.. . . .
12346-1
1~7~837
d) Change in defect structure factor, ~z - 0.038
e) Moles of silicon substituted per mole of
aluminum removed, (N-~z)/N _ 0.36
The data establish the feasibility of substitutin~ silicon
for framework aluminum in erionite by the method of the
present invention, Vsing the conditions described, however,
the efficiency of aluminum removal and of silicon substi-
tution are relatively low. Using more rigorous reaction
conditions results in the formation of a preferr~d LZ-"20 product
within the scope of the novel compositions of the invention.
Example 13
Fluorosilicate Treatment of Offretite to Produce LZ-217.
Approximately 50 grams of synthetic TMA offretite
was slowly calcined to 550C and held 24 hours. The
calcined offretite (Si02/A1203 molar ratio of 9.2~ was
slurried with 300 ml of 1.3 molar NH4 Cl solution at
reflux for one hour and filtered. The exchange was
repeated twice more and the product of the third exchange
was washed with hot distilled water until tests of the
wash water showed negative for chloride.
From the ammonium exchanged product, 5.0 ~m (anhydrous
weight) was slurried in 100 ml of distilled water heated
at 95C. A second solution of 50 ml containing 1.25 gm
(NH4)2SiF6 was added to the slurry in 2 ml increments at
a rate of 2 ml per five minutes, The stoichiometric ratio
of moles of silicon added as [!N.L4)2SiF6] to ~he moles of
aluminum present in the zeolite was 0.51. Following the
addition of the fluorosilicate solution the slurry was
digested for three hours at 95C then thoroughly washed
until tests of the wash water proved negative for both
aluminum and fluoride ions. The chemical analyses for the
starting NH4 Offretite and the product of the fluorosilicate
- 7S -
~ 7~837 12346-1
treatment are shown in Table 13A, bel~w:
TABLE l3A
Startin~ NH - LZ-217
Offretite 4 Product
K20, wt.% 2.48 1.47
(NH4)20, wt.% 5.31 2.72
A1203, wt.% 14.05 8.27
SiO2, wt.% 76.15 84.71
F2, wt.% - 0.12
SiO2/A1203 9.20 17.38
~ /Al 0.19 0.19
NH4 /Al 0.74 0.64
Cation Equivalent, M /Al 0.93 0.84
A comparison of the properties of the treated zeolite with
the starting material is shown in Table 13B, below:
TABLE 13B
Startin~ NH - LZ-217
Offretite 4 Product
Chemical SiO2/A1203 9.20 17.38
Chemical M+/Al 0.93 0.84
X-Ray Crystallinity
(I) By Peak Intensity 100 59
(lI) By Peak Area 100 60
Crystal Collapse Temp.,C(DTA) 1001 1043
Framework Infraret
Asymmetric Stretch, cm 11083 1094
Symmetric Stretch, cm 1789 793
Hydroxyl Infrared
Absolute Absorbance at 3710 cm 1 0.140 0.239
The framework mole fractions are set forth in Table 13C
below for the startin~ NH4 offretite and the LZ-217 product.
- 80 -
1~71~37 12346-1
TABLE 13_
a) M~le fraction of framework oxides (TO2); NH4 Offretite -
(A1~ 168Sio 773 0.059)2
LZ-217-(Alo 093sio.806 0.101)2
b) Mole fraction of aluminum removed; N - 0.075
c) % framework aluminum removed; N/a x lOO - 45
d) Change in defect structure factor, ~z - 0. 042
e) Moles of silicon substituted per mole of
aluminum removed, (N-~z) /N - O . 44
The data show that dealumination and silicon substitution
do occur in the erionite framework as a result of the
fluorosilicate treatment. Some degradation of the
structure seems apparent rro~ the X-ray crvstallinit,v data.
However, oxygen adsorption values for the starting NH4
Offretite and the treated product are nearly identical
(16-17 wt.% 2 at 100 Torr and -183C). The efficiency
of tealumination under the described conditions is quite
high and the efficiency of silicon substitution can be
increased with longer digestion times.
Example 14
Fluorosilicate Treatment of Zeolite W.
Eight gm of synthetic zeolite W (Si02/A1203 molar
ratio of 3.66) was slurried in 100 ml of 1;1 molar NH4Cl
solution at reflux for one hour and filtered. The exchange
was repeated twice more, the third and final exchange being
carried out over 16 hours. The product was then washed
with hot distilled water until tests of the wash water
showed neRative for chloride.
From the NH4W product, 5.0 gm (anhydrous weight)
was slurried in 100 ml distilled water heated at 95~C.
A second solution of 50 ml containing 2.21 gm (NH4)2SiF6
- 81 -
12346-1
1~7~33~
wad added to the slurry in 2 ml increments at a rate of
2 ml every five minutes. During the course of the fluoro-
silicate addition the slurry temperature was maintained
at 95C. The stoichiometric ratio of moles of Si added as
[(NH4)2SiF~7 to the moles of Al present in the zeolite was
0.49. Following addition of the fluorosilicate solution,
the slurry was digested for three hours at 95C then
filtered and thoroughly washed until tests of the wash
water proved negative for both aluminum and fluoride ions.
The chemical analyses for the starting NH4W and the product
of the fluorosilicate treatment are shown in Table 14A,
below:
TABLE 14A
Starting NH4W Trested NH
K20, wt.% 0.81 0.57
(NH4)20, wt.% 11.37 4.19
A1203, wt.~/o 25.99 11.88
SiO2, wt.% 59.40 81.67
F2, wt.% - 0.62
SiO2/A1203 3.88 11.67
K /A1 0.03 0-05
NH4~/Al 0.86 0.69
Cat$on Equivalent, M /Al 0.89 0.79
A comparison of the properties of the treated zeolite with
the starting material is shown in Table 14B, below:
_ ~ _
12346-1
1~7~&~37
TABLE l~B
Startinq NH4W Treated NH4W
Chemica~ SiO2/A12~3 3.88 11.67
Chemical Ml/Al 0.89 0.79
X-~ay Crystallinity
~) By Peak Intensity 100 ~7
~ By Peak A*ea 100 3S
Unit Cell ~a~) in A 20.2~6 20.145
Crystal Collapse ~emp., ~C (DTA) 1031 1025
Framework ~nfrared
Asymmetric Stretch, cm 1 1020 lOB4
Symmetric Stretch, cm~l 780 ~88
Hydroxyl Infrared
Abso'ute Absorbance at 3710 cm 1 o.o75 0.310
The framework mole fractions are set forth in Table 14C
below for the starting NH4W and the product zeolite.
TABLE 14C
a) Mole fraction of framework oxides (T02);
NH4W - (Alo 32gSio~639 0~032)2
Product(A10 127sio~74l 0.131)2
b) Mole fraction of sluminum removed; N - 0.202
c) % of framework aluminum removed; N/a x lO0 - 61
d) Change in defect structure factor; ~z - 0.099
e) Moles of silicon substituted per mole of
alumin~n removed;(N-~z)/N - 0.51
The tata establishes the feasibility of substituting
silicon for framework aluminum in zeolite W using the
process of the present invention. The X-ray crystallinity
tata couplet with some preliminary sdsorption tata, however,
inticate that an undue amount of crystal tegradation occurred
using the specifiet reaction conditions, with the consequent
protuct$on of a zeolite which toes not qualify as preferred LZ-216.
Evidence for silicon substitution is established by the shift
of framework infrared absorption bands to higher wavenumbers
- 83 -
12346-1
~7~837
and the relative size of the broad absorption band in the
hydroxyl .egion of the infrared spectrum which does not
correlate well with the high level of dealumination.
Chemical analysis data of both the solid and the liquid
phases of the reaction showed that silicon was indeed
incorporated into the zeolite. With no increased absor-
bance at 3745 cm 1 of the infrared spectrum indicative of
amorphous SiOH species as additional evidence, it must be
concluded that siliccr.was incorporated into the zeolite
framework during the treatment.
The cause of the structure degradation is believed
to be the extensive dealumination of the framework without
adequate silicon substitution. Accordin~ly the reactiD~ shoul~,
in order to produce LZ-216, be carried out in the presence
of a buffer solution such as ammonium acetate. As a
general proposition the higher the aluminum content of
the starting zeolite, the greater the need for buffering.
When this is tone, preferred LZ-216 results as the product.
Exam~le 15
Fluorosilicate Treatment of Zeolite Rho.
A sample of NH4Rho zeolite which contained a sparingly
soluble chloride salt was extracted for a period of ei~ht
days in a Soxhlet extraction apparatus. From the washed
NH4 Rho zeolite 25.0 gm (anhydrous weight) was slurried
in 200 ml distilled water heated at 75C. A second solution
of 100 ml containing 8.5 gm (NH4)2SiF6 was added to the
slurry in 3 ml increments at a rate of 3 ml every five
minutes. During the course of the fluorosilicate addition
the slurry temperature was maintained at 75C. The
stoichiometric ratio of moles of Si added as [!~H4)~LF5] to
- 84 -
~7~837
12346-1-C
the moles of Al present in the zeolite was 0.50. Following
addition of th fluorosilicate solution, the slurry was
disqested for 24 hours at 75C then filtered and thoroughly
washed until tests of the wash water proved negative for
both aluminum and fluoride ions. The chemical analyses for
the starting NHg Rho and the product of the fluoro-
silicate treatment are shown in Table 15A, below:
TABLE 15A
Starting NH4-Rho Treated NH4-Rho
Cs20, wt. ~ 3.02 2.07
~NH4)20, wt t 9.53 4.48
A123' t- ~ 19.30 11.03
SiO2, wt. ~ 6~.33 80.34
F2, wt. t - 0.06
Si2/A1203 5.92 12.36
Cs/Al 0.06 0.07
NH4~/A1 0.81 0.80
Cation Equivalent, Ml/A1 0.ô7 0.86
A compari~on ot the properties of the treated zeolite with tne
startlng NH4 Rho is ~hown ln Table 158, below.
TA~LE 150
Starting NH4-Rho Tre~ted NH4-Rno
Chemlcal 6iO2/A12035.92 12.36
Chemlcal ~/Al O.ô7 0.86
X-Ray Cryst~llinity
~I~ By Peak Intensity100 70
(II) By Peak Area 100 70
Unit Cell (aO) in A14.99114.927
Cry6tal Collapse Temp.,
C ~DTA) 975975, 1165
Framework Infrared
~ymmetrlc Stretch, cm 11049 1100, 1055
6ymmetrlc Stretch, cm 1~01 800
NydroKyl Int'r~red
Absolute Adsorb~nce
at 3710 cm 10.0750.0340
~71837 12346-1-C
The framework tetrahedral mole, fractions are set forth in
Table 15C below for both the starting NH4 ~ho and the
product zeolite.
Table 15C
~) MOle fr~cti~n of fr~ework oxides (T02~;
NH4Rh~ - (Alo.245Sl~.7? ~0.~31) ~
Pr~uct- (Alo ll~SIo.73 ~ .144)2
b) Mole fr~cti~n o~ ~luminum re~oved, N: - 0.126
c) Percent of fr~mework aluminum remo~ed, N/a x 100 - 51
d) Change in deect ~tructure factor, ~z - 0.113
e) Moles ~f ~ilicon substituted yer mole of
luminu~ rem wed, ~N- ~z)~N - 0.10
From the calculated unit cell compositions it appears
that a relatively small amount of silicon was incorporated
into the zeolite Rho framework during the treatment. This
is consistent with the very large shift of the asymmetric
stretch absorption band of the framework infrared region
and the lack of shift for the symmetric stretch band. The
efficiency of dealumination is high but under the
conditions employed, the ef~iciency of silicon substitution
is low. A LZ-214 product within the scope o~ the preferred
novel compositions of this invention and having the
characteristic crystal structure of zeolite Rho is produced
by digesting at a higher temperature and employing
additional buffering agents to protect the zeolite from
acid attack.
Example 16
Preparation of LZ-210.
Ten gm. (anhydrous weight) of ammonium zeolite Y
(SiO2/A1203 molar ratio - 4.93) were slurried in 100 ml of
3.4 molar ammonium acetate solution at 75C. A 50 ml
solution of water containing 4.63 gm Li2SiE6 2~20 was
- 86 -
~C
~L3l718~7
12346-1
added to the zeolite slurry in 1 ml incremenes at an addi-
tion rate of 1 ml. every 5 minutes. Followin~ addition o~
the Li2SiF6 solution, the reaction mixture was dip,ested
17 hours at 75C, with stirring. After the di~estion
period the reaction mixture was filtered and the filter
cake thorou~hly washed with distilled H20 until tests of
the wash water proved negative for both fluoride and
aluminum ion.s. The product was dried two hours at 110C
in air. The chemical and other analyses for the starting
NH4Y zeolite and the LZ-210 product zeolite are set
forth below.
NH4YLZ-210 Product
Na20-wt.% 2.5 0.6
(NH4)20-wt./o 9.5 3.7
Li20-wt.~/o - 0.4
A123 wt.% 22.2 9.7
SiO2-wt.% 64.4 85.0
SiO2/A1203(molar) 4-93 14.80
Na /Al 0.19 0.10
NH4+1A1 0.84 0.74
Li /Al - 0.13
Cation Equivalent (M /Al) 1.03 0.98
X-Ray Crystallinity:
(I) By Peak Intensity 100 83
Unit Cell Dimension(aO) 24.712 24.393
Framework Infrared:
Asymmetric Stretch, cm-l 1015 1061
Symmetric Stretch, cm 1 787 818
Hydroxyl Infrared:
Absolute Absorbance at 3710 cm 1 _ 0.160
Defect Structure Factor,z0.000 0.068
_ R7 -
1~718~7 12346-l
The framework mole fractions of tetrahedra are set forth
below for ~he startin~ NH4Y and the LZ-210 product.
a) Mole fraction of framewor~ oxides (T02);
NH4Y (Alo 2g9SiO.711 0)~2
LZ-210 (Alo lllSio.821 0.068)2
b) Mole fraction of aluminum removed; N - 0.178
c) % framework aluminum removed; N/a x lO0 - 62
d) Change in defect structure factor; ~z - 0.068
e) Moles of silicon substituted per mole of
aluminum removed; (N-~z)/N - O.62
In addition to the above described properties, the
crystal collapse temperature of the LZ-210 product as
measured by the standard DTA procedure was at 1128C.
The untreated NH4Y crystal collapse temperature measured
by the same DTA technique was at 890C.
Example 17
Preparation of LZ-210.
Ten g~. (anhydrous weight) of ar,~or.ium zeolite Y
(SiO2/A1203 ~olar ratio - 4.93) were slurried in 100 ml
of 3.4 molar am~onium acetate solution at 75C. Reagent
grate K2SiF6 (5.32 gm) crystals were added directly to
the slurry. The reaction mixture was digested at 75C
with stirring for two days, after which it was filtered
and the filter cake thoroughly washed with hot distilled
water until tests of the wash water proved negative for
both fluoride and aluminum ions. The X-ray powder pattern
obtained on the dried product did not show any extraneous
peaks indicative of impurities, precipitated in the zeolite
matrix. The chemical and other analyses for the starting
NH4Y zeolite and the LZ-210 product zeolite are set forth
below.
- 88 -
~71837 12346-~
NH4Y LZ-210 Pr~duct
Na20-wt.% 2.5 1.2
(NH4)20-wt. D/~ 9.5 1.6
K20-wt.% _ 5.6
A1203-wt . ~/o 22 . 2 11. 4
SiO2-wt.% 64.4 78.7
SiO2/A1203(molar) 4.93 11.72
Na /Al 0.19 0.18
NH +/Al 0.84 0.27
K /Al ~ 0 53
Cation Equivalent(M /Al) 1.03 0.98
X-Ray Crystallinity:
By Peak Intensity lO0 44
Unit Cell Dimension (aO) 24.712 24.514
Framework Infrared:
Asymmetric Stretch, cm 1 1015 1047
Symmetric Stretch, cm 1 787 799
Hytroxyl Infrared:
Absolute Absorbance at 3710 cm 1 _ 0. 210
Defect Structure Factor, z 0.000 0.089
The framework mole fractions of tetrahedra are set forth
below for the starting NH4Y and the LZ-210 product.
a) Mole fraction of framework oxites (T02);
NH4Y - (Alo.289sio.7ll 0) 2
LZ-210 - (Al~ 133Sio.773 0~o89)o2
b) Mole fraction of aluminum removed; N - 0.156
c) V/o framework aluminum removed; N/a x 100 - 54
d) Change in defect structure factor; ~z - 0. 089
e) Moles of silicon substituted per mole of
aluminum removed; (N-az)/N - O.43
~7~37 12346-1
In addition to the above described properties, the
crystal collapse temperature of the LZ-210 product as
measured by the standard DTA procedure was at 1072C.
The untreated NH4Y crystal collapse temperature measured
by the same DTA technique was at 890C.
Example 18
Ten gm. (anhydrous weight) of ammonium zeolite Y
(SiO2/A1203 ratio = 4.93) were slurried in 100 ml of 3.5
molar ammonium acetate solution at 75C. A 50 ml solution
of water containing 6.63 gm MgSiF6-6H20 was added to the
slurry in increments of 1 ml, at a rate of 1 ml every 5
minutes. Following addition of the MgSiF6 solution the
reaction mixture was digested 17 hours at 75C, with
stirring. After the digestion period, the reaction mixture
was filteret and the filter cake thoroughly washed with
tistillet water until tests of the wash water proved negative
for both fluoride and aluminum ions. The X-ray powder
pattern obtained on the product showed the presence of a
substantial amount of (NH4)M~AlF6 in the product. The
fluoride containing product was Soxhlet extracte~ w'th wa~e~
for 60 hours with the result that a negligible amount of
NH4MgAlF6 was removed from the product. Wet chemical
analyses and X-ray powder tiffraction both indicated that
the protuct was a mixture of ~5% zeolite and 15% NH4MgAlF6.
The chemical ant other analyses for the starting NH4Y zeolite
ant the LZ-210 protuct zeolite are set forth below:
- 90 -
~ 837 12346-1
As Prepared:
NH4Y LZ-210 Product
Na20, wt.% 2.5 0.6
(NH4)20, wt.% 9.5 3.2
MgO, wt.% - 6.9
A1203, wt.% 22.2 15.2
SiO2, wt.% 64.4 65.6
SiO2/A1203(molar) 4.93 7.30
F2 ~ Wt . % none 9.2
__ _ _
Corrected for 15 wt./,
NH4MgAlF6:
SiO2/A1203 4.93 9.93
Cation Equivalent(M /Al)1.03 1.12
X-ray Crystallinity intensity 100 100
Unit Cell Dimension(aO)24.712 24.454
Framework Infrared:
Asymmetric Stretch, cm 1 1015 1045
Symmetric Stretch, cm 1787 811
Hydroxyl Infrared:
Absolute absorbance @3710cm 1 _ 0 077
Defect Structure Factor, z 0,000 0 033
The framework mole fractions of tetrahedra are set forth
below for the starting NH4Y and the LZ-210 product which
has been corrected for the presence of 15 wt.% NH4MgAlF6.
a) Mole fraction of framework oxides(T02);
NH4Y - (A10.289SiO 711 0.000 2
LZ-210 - (Alo,l61Sio,806 0.033 2
b) Mole fraction of aluminum removed; N - 0.128
c) % framework aluminum removed; N/a x 100 - 44
d) Change in defect structure factor; ~z - 0.033
e) Moles of silicon substituted per mole of
aluminum removed; (N-az)/N _ 0 74
,., . ql
~7~837 12346-l
Exam~le 19
Fluorosilicate Treatment of NH4~-Omega Zeolite to
Produce LZ-213.
(a) A 5.0 gm. sample of Na,TMA-Omega, which had been
calcined to remove the tetramethylammonlum catlon~ ar.~ t~lDr ~n-
exchanged with ammonium cations, was slurried in 100 ml.
distilled water heated to 95~C. A second solution of 50
ml containing 1.48 gm (NH4)2SiF6 was added to the slurry
in 2 ml increments at a rate of 2 ml every 5 minutes.
During the course of the fluorosilicate addition, the slurry
temperature was maintained at 95C. The stoichiometric
ratio of moles of Si added as [(~H4)2SiF6~ to the moles of
Al present in the zeolite was 0~55. Following addition of
the fluorosilicate solution, the slurry was digested 3
hours at 95C, then filtered and thoroughly washed until
tests of the wash water proved negative for both aluminum
and fluoride ions.
The resulting product was only 30~ crystalline
indicating that the described treatment conditions were
too rigorous for the omega structure. No further charac-
terization was obtained with this sample.
tb) A second sample of ammonium-exchanged-calcined TMA
Omega zeolite, weighing 1.5 gm, was slurried in 200 ml
of 3.4 molar ammonium acetate solution and heated to 75C.
A second solution of 50 ml containing 0.36 gm (NH4)2SiF6
in water was added in one ml increments at a rate of one
m~ every minute. During the course of the fluorosilicate
addition, the slurry temperature was maintained at 75~C.
The stoichiometric ratio of moles of silicon added as
[(NH4)2SiF6] to the moles of aluminum present in the zeolite
_ 92 -
~ ~'73~83,7
12346-1
was 0.5. Followin~ addition of the fluorosilicate, th~
slurry was digested for 3 hours at 75~C, then filter~d
and thoroughly washed until tests of the wash water
proved negative for both aluminum an~ fltloride lons.
The chemical analyses for the starLin~ ~H4-Omega and th~
product of the fluorosilicate treatment are shown in Table
16A, below:
TABLE 16A
Starting NH4+-Omega LZ-213 Product
~a20, wt.-~ -- 0.16
(NH4)20, wt.-% 8.26 7.93
A1203, wt.-~ 19.56 18.35
SiO2, wt.-% 71.48 72.30
F2, wt.-Z -- 0.18
SiO2/A1203(molar) 6.20 6.67
Na+/Al -- 0.01
NH4 /Al 0.83 0.85
Cation Equivalent, M+/Al0.83 0.86
The comparison of the properties of the treated zeolite
with the starting material is shown in Table 16B, below:
TABLE 16B
Starting NH4+-Omega LZ-213 Product
X-Ray Crystallinity (I/Io) 100 109
Framework Infrared
Asymmetric stretch, cmIl 1040 1045
Symmetric stretch, cm 810 812
Hydroxyl Infrared
Absolute Absorbance at 3710 cm-l 0.039 0.061
Defect Structure Factor, z 0.017 0.026
_ 9~ _
12346-1
~'7~ ~ 37
The framework mole fractions are set forth below for the
starting NH4 -Omega and the LZ-213 product.
a) Mole Fraction of-Oxides(To2) NH4 -Omega
(Alo 239Sio.744 0.017) 2
LZ-213
(Alo 225Sio.749 0.026)o2
b) Mole fraction of aluminum removed, N - 0.014
c) Percent of framework alumimlm r~moved,
(~/a) x 100 - 6
d) Change in Defect Structure Factor, ~z - 0.009
e) Moles of silicon substituted per mole of
aluminum removed, (~-~z)/N - 0.36
This example is Sllustrative of a zeolite sample that
has been both treated too harshly (high temperature and pH,
concentrations) causing excessive crystal degradation,and too
mildly such that the dealu~.ination was too slow and silicon
substitution could not occur to a substantial level even though
the efficiency of silicon substitution was nearly 40%.
The novel zeolite compositions of the present invention
are useful in all adsorption, ion-exchange and catalytic
processes in which their less siliceous precursors have
heretofore been suitably employed. In general, because
they are more highly siliceous than their precursors
they are not only more thermally and hydrothermally stable
than those prior known materials but also have increased
resistance to~;ard acidic agents such as mineral and organic
acids, S02, S03,~Cx and the like. These new zeolites are
thus highly useful as selective adsorbents for these
materials from, for example, gas streams containing same
in contact sulfuric acid plants. Also since their crystal
structures are notably 1~ in defect structure and the
g ~
12346-1
~7~1837
zeolitic cations are ion-exchangeahle for other cation
species, both metallic and non-metallic, these zeolite
compositions are readily tailored by known methods to suit
the requirements of a broad spectrum of catalyst com?osi-
tions, particularly hydrocarbon conversion catalysts.
The non-metallic cation sites can also be thermally deca-
tionized in the known manner to produce the highly acidic
zeolite forms favored in most hydrocarbon conversion
reactions.
The novel zeolites of this invention can be compounded
into a porous inorganic matrix such as silica-alumina,
silica-magnesia, silica-zirconia, silica-aluminia-thoria,
silica-alumina-magnesia and the like. The relative propor-
tions of finely divided zeolite and inorganic matrix can
vary widely with the zeolite content ranging from about
1 to 90 percent by weight, preferably from about 2 to
about 50 percent by weight.
Amo~g the hydrocarbon conversion reactions catalyzed
by these new compositions are cracking, hydrocracking,
alkylation of both the aromatic and isoparaffin types,
isomerization including xylene isomerization, polymerization,
reforming, hydrogenation, dehydrogenation, transalkylation
and dealkylation, and catalytic dewaxing.
Using these zeolite catalyst compositions which contain
a hydrogenation promoter such as platinum or palladium,
heavy petroleum residual stocks, cyclic stocks and other
hydrocrackable charge stocks can be hydrocracked at
temperatures in the range of 400F to 825F using molar
ratios of hydrogen to hydrocarbon in the range of between
2 and 80, pressures between 10 and 3500 p.s.i.g., and a
liquid hourly space velocity (LHSV) of from 0.1 to 20,
preferably 1.0 to 10.
oc _
12346-1
1~7~837
The catalyst compositions employed in hydrocrackin~
are also suitable for use in reforming processes in which
the hydrocarbon feedstocks contact the catalyst at tempera-
tures of from about 700F to 1000F, hydrogen pressures
of from 100 to 500 p.s.i.g., LHSV values in the ran~e of
0.1 to 10 and hydrogen to hydrocarbon molar ratios in the
range of 1 to 20, preferably between 4 and 12.
These same catalysts, i.e. those containing hydro-
genation promoters, are also useful in hydroisomerization
processes in which feedstocks such as normal paraffins are
converted to saturated branched chain isomers. Hydroiso-
merization is carried out at a temperature of from about
200F to 600F, preferably 300F to 550F with an LHSV
value of from about 0.2 to 1Ø Hydrogen is supplied to
the reactor in ad~.ixture with the hydrocarbon feedstoc~
in molar proportions (H/Hc) of between 1 and 5.
At somewhat hi~her temperatures, i.e. from about 650F
to 1000F, preferably 850F to 950F and usually at some-
what lower pressures within the range of about 15 to 50
p,s,i.g,, the same catalyst compositions are used to hdyro-
isomerize normal paraffins, Preferably the paraffin feed-
stock comprises normal paraffins having a carbon number
range of C7-C20, Contact time between the feedstock and
the catalyst is generally relatively short to avoid unde-
sireable side reactions such as olefin polymerization and
paraffin cracking, ~HSV values in the range of 0,1 to 10,
preferably 1,0 to 6,0 are suitable.
The $ncrease in the molar SiO2/Al203 ratios of the
present zeolite compositions favor their use as catalysts
in the conversion of alkylaromatic compounds, particularly
the catalytic disproportionation of toluene, ethylene,
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7~337
trimethyl benzenes, tetramethylbenæenes and the like. In
the disporportionation process isomerization and trans-
alkylation can also occur. Advantageously the catalyst
form employed contains less than 1.0 weight percent sodi~m
as Na20 and is principally in the so-called hydrogen cation
or decationized form. Group VIII noble metal adjuvents
alone or in conjunction with Group VI-B metals such as
tungstem, molybdenum and chromium are preferably included
in the catalyst composition in amounts of from about 3 to
15 weight-% of the overall composition. Extraneous hydro-
gen can, but need not be present in the reaction zone
which is maintained at a temperature of from about 400 to
750F, pressures in the range of 100 to 2000 p.s.i.g. and
LHSV values in the range of 0.1 to 15.
Catalytic cracking processes are preferablv carried
out using those zeolites of this invention which have SiO2/
A1203 molar ratios of 8 to 12, less than 1.0 weight-%
Na20 and feedstocks such as gas oils, heavy naphthas,
deasphalted crude oil residua etc. with gasoline being
the principal desired product. The decationized form of
the zeolite and/or polyvalent metal cationic form are
advantageously employed. Temperature conditions of
850 to 1100F, LHSV values of 0.5 to 10 and pressure
conditions of from about 0 to 50 p.s.i.g. are suitable.
Dehydrocyclization reactions employing paraffinic
hydrocarbon feedstocks, preferably normal paraffins having
more than 6 carbon atoms, to form benzene, xylenes, toluene
and the like are carried out using essentially the same
reaction conditions as for catalytic cracking. The
preferred form of the zeolite employed as the catalyst is
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~ 7~37 12346-l
that in which the cations are principally metals of ~,roup
II-A and/or II-B such as calcium, strontium, ma~nesium.
Group VIII non-noble metal cation can also be employed such
as cobalt and nickel.
In catalytic dealkylation wherein it is desired to
cleave paraffinic side chains from aromatic nuclei without
substantially hydrogenating the ring structure, relatively
high temperatures in the range of about 800-1000F are
employed at moderate hydrogen pressures of about 300-lO00
p.s.i.g , other conditions being similar to those described
above for catalytic hydrocracking. Preferred catalysts
are of the relatively non-acidic type described above in
connection with catalytic dehydrocyclization. Particularly
desirable dealkylation reactions contemplated herein include
the conversionof methylnaphthalene to naphthalene and toluene
and/or xylenes to benzene.
In catalytic hydrofining, the primary ob;ective is to
promote the selective hydrodecomposition of organic sulfur
and/or nitrogen compounds in the feed, without substantially
affecting hydrocarbon molecules therein. For this purpose
it is preferred to employ the same general conditions
described above for catalytic hydrocracking, and catalysts
of the same ~eneral nature described in connection with
dehydrocyclization operations. Feedstocks include gasoline
fractions, kerosenes, jet fuel fractions, diesel fractions,
light and heavy gas oils, deasphalted crude oil residua
and the like any of which may contain up to about 5 weight-
percent of sulfur and up to about 3 weight-percent of
nitrogen.
Similar conditions can be employed to effect hydro-
fining, i.e., denitrogenation and desulfuriæation, of
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~ 3 ~ 12346-1
hvdrocarbon feeds containing substantial proportions of
organonitrogen and organosulfur compounds. As observed
by D.A. Young in ~.S.P. 3,783,123, it is generally recog-
nized that the presence of substantial amounts of such
constituents markedly inhibits the activity of catalysts
for hydrocracking. Consequently, it is necessary to operat~
at more extreme conditions when it is desired to obtain
the same degree of hydrocracking conversion per pass on a
relatively nitrogenous feed than are required with a feed
containing less organonitrogen compou~.ds. Conseque..~
the conditions under which denitrogenation, desulfuriza~ion
and/or hydrocracking can be most expeditiously accomplished
in any given situation are necessarily determined in view
of the characteristics of the feedstocks in particular
the concentration of organonitrogen compounds in the feed-
stock. As a result of the effect of organonitrogen compounds
on the hytrocracking activity of these compositions it is
not at all unlikely that the conditions most suitable for
denitrogenation of a given feedstock having a relatively
high organonitrogen content with minimal hydrocracking,
e.g., less than 20 volume percent of fresh feed per pass,
might be the same as those preferred for hydrocracking
another feedstock having a lower concentration of hydro-
cracking inhibiting constituents e.g., organonitrogen
compounds. Consequently, it has become the practice in
this art to establish the conditions under which a certain
feed i8 to be contacted on the basis of preliminary screen-
ing tests with the specific catalyst and feedstocks.
Isomerization reactions are carried out under conditions
similar to those described above for reforming, using some-
what more acidic catalysts. Olefins are preferably
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~ 7~337 l2346 l
isomerized at temperatures of 500-900F, while paraffins,
naphthenes and alkyl aromatics are isomerized at tempera-
tures of 700-1000F. Particularly desirable isomerization
reactions contemplated herein include the conversion of
n-heptane and/or n-octane to isoheptanes, iso-octanes,
butane to iso-butane, methylcyclopentane to cyclohexane,
meta-xylene and/or ortho-xylene to paraxylene, l-butene to
2-butene and/or isobutene, n-hexene to isohexene, cyclo-
hexene to methyl-cyclopentene etc. The preferred cation
form of the zeolite catalyst is that in which the ion-
exchange capacity is about 50-60 percent occupied by
polyvalent metals such as Group II-A, Group II-B and rare
earth metals, and 5 to 30 percent of the cation sites are
either decationized or occupied by hydrogen cations.
For alkylation and dealkylation processes the
polyvalent metal cation form of the zeolite catalyst is
preferred with less than 10 equivalent percent of the
cations being alkali metal. When employed for dealkylation
of alkyl aromatics, the temperature is usually at least
350F and ranges up to a temperature at which substantial
cracking of the feedstock or con~ersion products occurs,
generally up to about 700F, The temperature is preferably
at least 450F and not greater than the critical tempera-
ture of the compound undergoing dealkylation. Pressure
contitions are applied to retain at least the aromatic feed
in the liquid state. For alkylation the temperature can be
as low as 250F but is preferably at least 350F. In
alkylating benzene, toluene and xylene, the preferred
alkylating agents are olefins such as ethylene and propy-
lene.
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~ 71 ~ 3 ~ 12346-1
The hydrothermal stability of many of the zeolite
compositions of this invention can be enhanced by ccnven-
tional steaming procedures. In general the ammonium or
hydrogen cation forms of the zeolite are contacted with
steam at a water vapor pressure of at least about 0.1 psla,
preferably at least 0.2 psia up to several atmospheres.
Preferably steam at one atmosphere is employed. The steaming
temperatures range from 100C up to the crystal destruc-
tion temperature of the zeolite, but are preferably in the
range of 600C to 850C. Steaming periods of a few minutes,
e.g. 10 minutes, up to several hours can be employed depend-
ing upon the specific temperature conditions. The steaming
also produces changes in the selectivity of the catalyst
in many cases.
In the above-described catalytic conversion processes
the preferred zeolite catalysts are those in which the
zeolite constituent has pores of sufficient dlameter
to adsorb benzene. Such zeolites include LZ-210, LZ-211,
LZ-212, LZ-217 and LZ-213
Example 20
In order to evaluate the catalytic activity of LZ-210
in the catalytic cracking of a gas oil feedstock, a sample
of the catalyst was prepared as follows: 990 g. (NH4)2SiF6
were dissolved with stirring $nto 3.8 liters of distilled
water at 50C. The solution was put into a dropping funnel
fitted on a three-necked round-bottom flask, A solution
of 1500 grams of ammonium acetate in 10 liters of water
was then added to the flask. Ammonium zeolite Y in the
amount of 2500 grams (anhydrous weight, molar SiO2/A1203 =
4.87) was slurried up in the ammonium acetate solution at
75C. A mechanical stirred was fitted to the center hole
- 101 -
337 l2346-l
of the flask, which was als~ fitted with the necessary
thermo-couples and temperature controllers. Addition of
the 3.~ liters of (NH4)2SiF6 solution in lO0 ml. incre-
ments begun with a 5-minute interval between each sddition.
The initiàl pH of the slurry was measured at 5.74 and
after all of the (NH4)2SiF6 solution was added to the pH
of the slurry was 5.38. The mixture was heated at 95C
with stirring for an additional 18 hours, the dropping
funnel ha~ing been replaced with a condenser. The stoichio-
metry of the reaction was of the order of one Si added as
(NH4)2SiF6 for every two Al atoms present in the zeoli~e.
At the conclusion of the reaction the pH of the slurry was
5.62. The reaction mixture was then filtered and the solids
washed with about 25 liters of hot tistilled water, until
quantitative tests indicated absence of NH3 and aluminum in
the effluent wash water. It was then dried 2 hours at 110C.
The product had a unit cell dimension (aO) of 24.41 A, a
cation equivalence of 0,94, and the following compositional
mole ratios:
Na20/A1203 e 0~ 076
(NH4)20/A1203 e 0, 862
SiO2/A1203 - 9. 87
The powdered LZ-210 was admixed with 1.5 times its weight
of alumina and formed by means of extrusion into 1/16"
pellets. The pellets were calcined at 500C for 6 hours.
The resulting extrudates were sized to 60-lO0 mesh and
evaluated for cracking actiivty using a gas oil feedstock,
(Amoco FHC-893), in accordance with the procedure of AS~I
test No. D 032,04. The following results were obtained:
- 102 -
~t7~7 12346-1
AST~ Conversion 86.0
G l 35.0
Gasoline2 28.5
Coke3 8.89
H2 0.14
Cl 0.38
C2 + C2 = 1.3
C3 2 5
C3 2.6
i-C4 6.5
n-c4 3.2
c4 = 10.8
C5 5.1
C5 2 5
(1) weight % feed converted to gas
~2~ Gasoline - wt. product (180F-421F)/Total product
(3) Weight % feed converted to coke (gravimetric)
ExamPle21
A sample of LZ-210 having a SiO2/A1203 molar ratio of
9.6 and containing 0,7 weight % Na20 was loaded with 0.53
weight percent palladium and composited with sufficient
alumina to form an 80% Pd/LZ-210 - 20% A1203 catalyst
composition having an average bulk density of 0.48 cc./g.
This catalyst composition was tested for gasoline hydro-
cracking performance using the following test conditions:
Feedstock - Gas Oil, API - 39.0, BP.R = 316-789F.
Pressure - 1450 psig.
H2/Oil c 8000 SCF/BBL.
To determine the second stage hydrogenation activity of the
catalyst, the feed was doped with 5000 p?m sulfur as
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37 12346-1
throphene. The activity in this regard was, in terms of
the temperature required to obtain a 49.0 API product
after 100 hours in stream, 498F. To determine the first
stage (cracking) activity, the feed was doped with 5000
ppm sulfur as thiophene and 2000 ppm nitrogen as 5-butyla~ine.
The activity in this regard, in terms of the temperature
required to obtain a 47.0 API product after 100 hours on
stream, was 692F.
_ 1 nL _
