Note: Descriptions are shown in the official language in which they were submitted.
I 1 77~B5
01 -1-
CRYSTALLINE SILICATE PARTICLE HAVING
AN ALUMINU~-COMTAINING OUTER S~ELL
05 AND HYDROCARBON CONVERSION PROCESSES
TECHNICAL FIELD
This invention relates to crystalline silicate
zeolites, to their synthesis, and to hydrocarbon conver-
sion processes using themi It more particularly relates
to the synthesis and use of a crystalline silicate having
an outer shell which contains aluminum, yet which has the
same X-ray diffraction pattern and crystal structure as
the core crystalline silicate.
Certain of the materials disclosed herein, and
their syntheses, are well known. RE 29,948, Dwyer et al,
March 27, 197~, discloses organosilicates having the ZSM-5
structure; U.S. 4,061,724, Grose et al, December 6, 1977,
discloses silicalite; Bibby et al, Nature Vol. 28,
20 pp. 664-665 (August 23, 1979), discloses "silicalite-2".
The aluminosilicate zeolites ZSM-5 and ZSM-ll are
described in U.S. Patent Nos. 3,702,886 and 3,709,979.
Because of their ordered, porous structure,
creating interconnected cavities, the crystalline sili-
cates, and the ZSM zeolites, are selective toward certain
molecules. That is to say, the pores accept f~r adsorp-
tion molecules of certain dimensions while rejecting thoseof larger dimensions. No known art discloses or suggests
increasing selectivity by essentially activating the
surface of the crystalline silicate catalyst with an outer
isocrystalline layer of aluminum-containing zeolite.
Several issued patents do disclose inactivating the sur-
face of aluminosilicates by depositing an isocrystalline
outer shell of aluminum-free material--U.S. 4,088,605,
Rollman, May 9, 1978; U.S. 4,148,713, Rollman, April 10,
1979; and U.S. 4,2~3,869, ~llman, May 20, 198
DESCRIPTION OF SPECIFIC EMBODIMENTS
I have discovered particles, comprising an i~ner
portion and an outer portion disposed as a shell around
said inner portion wherein said outer portion has the same
77465
crystal structure as said inner portion, said inner portion
comprising an intermediate pore size crystalline silicate which
is substantially free of aluminum and said outer portion
comprising alumina.
: In another aspect, the invention provides a process for
preparing the particles as defined above comprising: (1) initiat-
ing crystallization in a crystallization medium substantially
free of aluminum to produce the intermediate pore size crystal-
line silicate; (2) adding a source of aluminum to said crystal-
lization medium; and (3) crystallizing onto said crystalline
silicate the isostructural outer portion which comprises alumina.
The invention may also be defined as a process for
preparing the particles as defined above, comprising; (1) cry-
stallizing the intermediate pore size crystalline silicate from
a first reaction medium substantially free of aluminum; (2)
removing said crystalline silicate from said first reaction
medium; (3) adding said crystalline silicate to a second reaction
medium comprising sources of aluminum; and (4) crystallizing the
isostructural, alumina containing outer layer onto said crystal-
line silicate.
I have also discovered a hydrocarbon conversion process,comprising containing a hydrocarbonaceous feedstock with a par-
ticle, comprising an inner portion and an outer portion disposed
as a shell around said inner portion wherein said outer portion
has the same crystal structure as said inner portion, said inner
portion comprising an intermediate pore size crystalline silicate
which is substantially free of aluminum, and said outer portion
comprising alumina, under hydrocarbon conversion conditions.
The crystalline silicates useful herein are essential~
ly aluminum-free materials of intermediate pore size, and
can be the silicaceous analogues of intermediate pore size
-- 2
^ 177465
zeolites such as ZSM-5 and ZSM-ll. In spite of their low
aluminum content, the crystalline silicates are useful in
cracking and hydrocracking and are outstandingly useful in
high pressure catalytic dewaxing to produce olefins, and in
olefin polymerization reactions, as well as other petroleum
refining processes.
Although they have unusually low aluminum contents,
i.e., high silica to alumina ratios, they are very active even
when the silica to alumina ratio exceeds 1000:1. The activity
is surprising since catalytic activity is generally attributed
to framework aluminum atoms and cations associated with these
aluminum atoms. These materials retain their crystallinity
for long periods even in the presence of steam at high
temperature, conditions which induce irreversible collapse
of the framework of many 2eolites,- e.g., of the X and A type.
Furthermore, carbonaceous deposits, when formed, can be
removed by burning at higher than usual temperatures to
restore activity. In many environments these crystalline
silicates exhibit a very low coke forming capability, a
characteristic conducive to very long times on stream between
burning regenerations.
By "intermediate pore size" as used herein is meant
an effective pore aperture in the range of about 5.0 to 6.5
Angstroms when the crystalline silicate is in the H-form.
Silicates having pore apertures in this range tend to have
unique molecular sieving characteristics. Unlike small pore
zeolites such as erionite, they will allow hydrocarbons having
some branching into the zeolitic void spaces. Unlike large
pore zeolites such as the faujasites, they can differentiate
between n-alkanes and slightly branched alkanes on the one hand
and larger branched alkanes having, for example, quaternary
3 -
~ 1 77~5
carbon atoms.
The effective pore size can be measured using
standard adsorption technIques and hydrocarbonaceous compounds
of known minimum kinetic diameters. See Breck, Zeolite
Molecular Sieves, 1974 (especially Chapter 8) and Anderson et
al, J. Catalysis 58, 114 (1979~.
Intermediate pore size crystalline silicates in the
H-form will typically admit molecules having kinetic diameters
of 5 to 6 Angstroms with little hindrance. Examples of such
compounds (and their kinetic diameters in Angstroms) are:
n-hexane (4.3), 3-methylpentane (5.5), benzene (5.85), and
toluene (5.8). Compounds having kinetic diameters of about
6 to 6.5 Angstroms can be admitted into the pores, depending
on the particular silicate, but do not penetrate as quickly
and in some cases, are effectively excluded. Compounds
having kinetic diameters in the range of 6 to 6.5 Angstroms
include: cyclohexane (6.0), (2,3-dimethylbutane (6.1), 2,2-
dimethylbutane (6.2), m-xylene (6.1), and 1,2,3,4-tetramethy-
lbenzene (6.4). Generally, compounds having kinetic diameters
of c3reater than about 6.5 Angstroms cannot penetrate the pore
apertures and thus cannot be adsorbed in the interior of the
crystalline silicate. Examples of such larger compounds
include: o-xylene (6.8), hexamethylbenzene (7.1), 1,3,5,-
trimethylbenzene (7.5), and tributylamine (8.1).
The preferred effective pore size range is from
about 5.3 to about 6.2 Angstroms. Silicalite, for example,
falls within this range. The preferred crystalline silicates
exhibit the X-ray diffraction pattern of ZSM-5 or ZSM-ll or both.
In performing adsorption measurements to determine
pore size, standard techniques are used. It is convenient
to consider a particular molecule as excluded if it does not
746~
reach at least 95~ of its e~uilibrium adsorption value on the
zeolite in less than about 10 minutes (p/po=0.5; 25C).
The silica to alumina ratio referred to may be
determined by conventional analysis. This ratio is meant to
represent, as closely as possible, the ratio (on a molar basis)
of silica to alumina in the rigid anionic framework of the
silicate crystal and to exclude aluminum in the binder or in
cationic or other form within the channels. Although
crystalline silicates with a silica to alumina ratio of at
least 200:1 are useful, it is preferred to use crystalline
silicates having higher ratios of at least about 500:1 and more
preferably, lO00:1. Such materials, after activation, acquire
an intracrystalline sorption capacity for normal hexane which,
at low relative pressures is greater than that for water.
As noted above, crystalline silicates used in the
process of the present invention have been reported in the
literature in several places. "Silicalite" (United States
4,061,724) has, as synthesized, a specific gravity at 25C of
l.99 + 0.05 g/cc as measured by water displacement. In the
calcined form (600C in air for 1 hour), silicalite has a
specific gravity of 1.70 + 0.05 g/cc. With respect to the
mean refractive index of silicalite crystals, values obtained
by measurement of the as synthesized form and the calcined
form (600C in air for l hour) are, respectively, 1.48 + 0.01
and 1.39 + 0.01.
The X-ray powder pattern of silicalite (600C
calcination in air for l hour) has as its six strongest
lines (i.e., interplanar spacings) those set forth in Table A
("S" - strong, and "VS" - very stong):
~ 177465
TABLE A
d-A ''Relati've' Intensity
... .
11.1 + 0.2 VS
10.0 ~ 0.2 VS
3.85 + 0.07 VS
3.82 _ 0.07 S
3.76 + 0.05 S
3.72 _ 0.05 S
The following Table B lists the data representing
X-ray powder diffraction pattern of a typical silicalite
composition containing 51.9 moles of SiO2 per mole of (TPA)2O,
which has been calcined in air at 600C for 1 hour.
TABLE B
d-A Relative Intensity d-A _ Relative Intensity
11.1 100 4.35 5
10.02 64 4.25 7
9.73 16 4.08 3
8.99 1 4.00 3
8.04 0.5 3.85 59
7.42 1 3.82 32
7.06 0.5 3.74 24
6.68 5 3.71 27
6.35 9 3.64 12
5.98 14 3.59 0.5
5.70 7 3.~8 3
5.57 8 3.44 5
5.36 2 3.34 11
5.11 2 3.30 7
5.01 4 3.25 3
4.98 5 3.17 0.5
4.86 0.5 3.13 0.5
4.60 3 3.05 5
4,44 0.5 2.98 10
- 5a -
.,-
.
~ ~77~B5
01 -6-
Crystals of silicalite in both the as synthe-
sized and calcined form are orthorhombic and have the
05 following unit cell parameters: a = 20.05 A, b = 19.86 A,
c = 13.36 A, with an accuracy of + 0.1 A on each of the
values.
The pore diameter o~f silicalite is approximately
6 Angstrom units and its pore volume is 0.18 g/cc as
determined by absorption. Silicalite adsorbs neopentane
(6.2 A kinetic diameter) slowly at ambient room tempera-
ture. The uniform pore structure imparts size-selective
molecular sieve properties to the composition/ and the
pore size permits separation of p-xylené from o-xylene and
ethylbenzene as well as separations of compounds having
quaternary carbon atoms from those having carbon-to-carbon
linkages of lower value.
The crystalline silicates of U.S. RE 29,948
(incorporated by reference) are disclosed as having a
composition in the anhydrous state:
0.9 i 0.2 [xR2O + (l-x) M2/nO]: <.005
A12O3:>1SiO2
where M is a metal, other than a metal of Group IIIA, n is
the valence of said metal, R is an alkyl ammonium radical
and x is a number greater than 0 but not exceeding 1, said
organosilicate being characterized by the X-ray diffrac-
tion pattern of Table C.
TABLE C
Interplanar spacing d(A)Relative Intensity
11.1 S
10.0 S
7.4 W
7.1 W
6.3 W
6.4 ) W
5.97)
5.56 W
5.01 W
4.60 W
~.25 W
^ ~77~5
TABLE C (Cont'd)
Interplanar spacing d(A)Relative Intensity
3.85 VS
3.71 S
3.04 W
2.99 W
2.94 W
The crystalline silicate polymorph of United States
4,073,865 is disclosed as having a specific gravity of 1.70 +
0.05 g/cc and a mean refractive index of 1.39 + 0.01 after
calcination in air at 600C, as prepared by a hydrothermal
process in which fluoride anions are included in the reaction
mixture. The crystals, which can be as large as 200 microns,
exhibit a substantial absence of infrared adsorption in the
hydroxyl-stretching region and are organophilic. They exhibit
the X-ray diffraction pattern of Table D.
TAsLE D
d(A) Intensity
11.14 91
~0 10.01 100
9.75 17
8.99
8.04 0~5
7.44 0.5
7.08 0.2
6.69 4
6.36 6
5~99 10
5.71 5
5.57 5
~`
~ 1 77~65
TABLE D (Con t ' d)
d (A) In tensity
5.37
5.33
5.21 0,3
5.12 1.5
5.02 3
4.97 6
4.92 0.6
- 7a -
' ' :
1 177~65
Ol -8-
TABLE D (Cont'd)
_d(A) Intensity
oS4.72 0.5
4.~2 2
4.47 0.6
4.36 ~ 3
4.25 4
104.13 0.5
4.08 1.5
4.00 3
3.85 44
3.82 25
153.71 21
3.65 5
3.62 5
3.59
3.48 1.5
203.45 3
3.44 3
3.35 3
3.31 5
3.25 1.5
253.23 0.~
3.22 0.5
The literature describes the following method
for the preparation of the crystalline silicate,
"silicaiite-2" (Nature, August, 1979):
The silicalite-2 precursor is prepared
using tetra-n-butylammonium hydroxide
only, although adding ammonium hydroxide
or hydrazine hydrate as a source of
extra hydroxyl ions increases the reac-
tion rate considerably. A successful
preparation is to mix 8.5 moles SiO2 as
silicic acid ~74% Sio2), 1.0 mole tetra-
n-butylammonium hydroxide, 3.0 moles
NH40H and 100 moles water in a steel
bomb and heat at 170C for 3 days.
I i774B5
01 ~9~
The preparation of crystalline silicates gener-
ally involves the hydrothermal crystallization of a
05 reaction mixture comprising water, a source of silica and
an organic templating compound at a pH of 10 to 14.
Representative templating moieties include quaternary
cations such as XR4 wherein X is phosphorous or nitrogen
and R is an alkyl radical containing from 2 to 6 carbon
atoms; e.g., tetrapropyl ammonium hydroxide or halide.
When the organic templating compound is provided
to the system in the hydroxide form in sufficient quantity
to establish a basicity equivalent to a p~l of 10 to 14,
the reaction mixture need contain only water and a reac-
tive form of silica as additional ingredients. In thosecases in which the pH is required to be increased to about
10, ammonium hydroxide or alkali metal hydroxides can be
suitably employed for that purpose, particularly the
hydroxides of lithium, sodium or potassium. It has been
found that not more than 6.5 moles of alkali metal oxide
per mole-ion of alkylonium compound is required for this
purpose even if none of the alkylonium compound is pro-
vided in the form of its hydroxide.
The specific crystalline silicates described,
when prepared in the presence of organic cations, are
catalytically inactive, possibly because the intracrystal-
line free space is occupied by organic cations from the
forming solution. The silicates may, however, be
activated by heating in an inert atmosphere at 1000F for
1 hour, followed by base exchange with ammonium salts and
followed by a further calcination at 1000F in air.
The silicates can be used either in the alkali
metal form, e.g., the sodium form, the ammonium form, the
hydrogen form, or another univalent or multivalent cat-
ionic form. Preferably, one or the other of the last twoforms is employed. They can also be used in lntimate
combination with a hydrogenating component such as
tungsten, vanadium, molybdenum, rhenium, nickel, cobalt,
chromium, manganeser or a noble metal such as platinum or
palladium where a hydrogenation-dehydrogenation function
~ )77~65
01 -10-
is to be performed. Such component can be exchanged into
the composition, impregnated therein or physically
05 intimately admixed therewith. Such component can be
impregnated in or on to the present catalyst such as, for
example, by in the case of platinum, treating the zeolite
with a platinum metal-contai"ing ion. Thus, suitable
platinum compounds include chloroplatinic acid, platinous
chloride and various compounds containing the platinum
amine complex.
The compounds of the useful platinum or other
metals can be divided into compounds in which the metal is
present in the cation of the compound and compounds in
which it is present in the anion of the compound. Both
types which contain the metal in the ionic state can be
used. A solution in which platinum metals are in the form
of a cation or cationic complex, e.g., Pt(21H3)6C14 is
particularly useful. For some hydrocarbon conversion
processes, this noble metal form of the catalyst is
unnecessary such as in low temperature, liquid phase
ortho-xylene isomerization.
The catalyst, when employed either as an
adsorbent or as a catalyst in one of the aforementioned
processes, should be dehydrated at least partially. This
can be done by heating to a temperature in the range of
200C to 600C in an atmosphere such as air, nitrogen,
etc., and at atmospheric or subatmospheric pressures for
between 1 and 48 hours. Dehydration can also be performed
at lower temperatures merely by placing the catalyst in a
vacuum, but a longer time is required to obtain a suffi-
cient amount of dehydration.
In a preferred aspect of this invention, the
catalysts hereof are selected as those having a crystal
framework density, in the dry hydrogen form, of not sub-
stantially below about 1.6 grams per cubic centimeter~
The dry density for known structures may be calculated
from the number of silicon plus aluminum atoms per 1000
cubic Angstroms, as given, e~g., on page 19 of the article
on Zeolite Structure by W. M~ Meir. This paper,
~ 17~65
is included in "Proceedings of the Conference on Molecular
Sieves, London, April 1967", published by the Society of
Chemical Industry, London, 1968. When the crystal structure is
unknown, the crystal framework density may be determined by
classical pycnometer techniques. For example, it may be
determined by immersing the dry hydrogen form of the zeolite in
an organic solvent which is not sorbed by the crystal. It is
possible that the unusual sustained activity and stability of
this class of zeolites is associated with its high crystal
anionic framework density of not less than about 1.6 grams per
cubic centimeter. This high density of course must be associ-
ated with a relatively small amount of free space within the
crystal, which might be expected to result in more stable
structures. This free space, however, is important as the locus
of catalytic activity.
Following completion of synthesizing the crystalline
silicate, it is essential, for the purposes of this invention,
to reduce or eliminate the nucleation of new silicate crystals
while at the same time keeping the crystal growth high. To
~0 produce the outer, aluminum-containing shell, it is also
essential that reactive aluminum be added to the reaction
mixture.
It is therefore necessary to process the silicate and
to add an aluminum-containing mixture to obtain crystallization
of SiO2 and A1203 on the surface of the silicate, the SiO2/A1203
mixture having the same crystal structure as the core silicate.
This can be accomplished by a total replacement of the reaction
mixture or by adding an aluminum-containing solution to the
original reaction mixture.
Typical reaction conditions include heating the
~ 1 77~5
mixture at a temperature of from about 80C to about 200C for
a period of time from about 4 hours to about 30 days. As in
the case of general aluminosilicate synthesis, the digestion of
the gel particles is carried out until the crystalline alumino-
silicate layer forms completely as the outer shell of the
crystalline particles. The product crystals are then separated,
as by cooling and filtering, and are water washed and dried at
from about 80C to about 150C.
The most efficient method of preparation is to form
the crystalline silicate, and then use the crystalline silicate
particles as seeds in the reaction mixtures normally used to
prepare intermediate pore size zeolites. Either the pH of the
reaction mixture or the temperature can be used to control and
minimize the nucleation of separate zeolite particles. Lower
pH's, e.g., 9-10, reduce silica solubility thereby limiting the
number of nucleation sites and causing aluminosilic~te deposi-
tion on the seeds. Lower temperatures slow the rate of crystal
growth and nucleation so as to cause aluminosilicate deposition
on the seeds. At lower pH's, e.g., 9-10, a normal temperature
range for hydrothermal crystallization can be used. I prefer
to control the temperature to the range of about 100C to 120C
and the pH to about 10-12. Under these conditions nucleation
of the zeolite is minimized while the aluminosilicate layer
continues to form on the exterior of the silicate seed. Seeding
techniques such as those of United States 4,175,114, Plank et
al., November 20, 1979, which use an alcohol and ammonium hydrox-
ide mixture in place of tetrapropylammonium cations can also be
used. Using these techniques, I prefer to control the pH to
11-14 and the temperature to about 120C to 160C. Generally,
the organic cation/SiO2 mole ratio and the hydroxide content of
- 12 -
; 177~65
the mixture from which the crystalline silicate is prepared
are higher than in the mixture in which the isostructural
alumina containing layer is crystallized onto the silicate.
Members of the present ~amily of materials can
have the original cations associated therewith replaced by
a wide variety of other cations according to techniques well
known in the art. Typical replacing cations would include
hydrogen, ammonium and metal cations includin~ mixtures of
the same. Of the replacing metallic cations,
- 12a -
- ~ ~77a~65
01 -13-
particular preference is given to cations of metals such
;as rare earth metals, manganese and calcium, as well as
`05 metals of Group II of the Periodic Table, e.g., zinc and
Group VIII of the Periodic Table, e.g., nickel.
Typical ion-exchange techniques include contact-
ing the members of the family of zeolites with a salt of
the desired replacing cation or cations. Although a wide
variety of salts can be employed, particular preference is
given to chlorides, nitrates and sulfates.
Representative ion-exchange techniques are dis-
closed in a wide variety of patents including U.S. Patent
Nos. 3,140,249; 3,14~,~51; and 3,140,253.
Following contact with the salt solution of the
desired replacing cation, the materials are then prefer-
ably washed with water and dried at a temperature ranging
from 150F to about 600F and thereafter calcined in air
or other inert gas at temperatures ranging from about
20 500F to about 1200F for periods of time ranging from 1
to 48 hours or more.
Regardless of the cations replacing the sodium
in the synthesized form of the catalyst, the spatial
arrangement of the aluminum, silicon and oxygen atoms
~25 which form the basic crystal lattices in any given zeolite
;of this invention will remain essentially unchanged by the
described replacement of sodium or other alkali metal as
could be determined by taking an X-ray powder diffraction
pattern of the ion-exchanged material. For example, the
silicate/aluminosilicate structure of the ZSM-5 X-ray dif-
fraction pattern will reveal a pattern substantially the
same as that set forth in Table C above.
~The materials of the instant invention are manu-
`~factured into compositions having a wide variety of shapes
and sizes. Generally speaking, the particles can be in
the form of a powder, a granule, or ~ molded product, such
as extrudate having particle size sufficient to pass
through a 2 mesh (T~ler) screen and be retained on a 400
mesh tTyler) screen. In cases where the catalyst is
~ ~77~6~
01 -14-
molded, such as by extrusion, the crystalline silicate/
aluminosilicate can be extruded before drying or dried or
05 partially dried and then extruded.
In the case of many zeolites, it is desired to
incorporate the crystalline silicates/aluminosilicates of
my invention with other materials resistant to the
temperatures and other conditions employed in organic
conversion processes. Such materials include active and
inactive materials and synthetic or naturally occurring
zeolites as well as inorganic materials such as clays,
alumina, silica, and/or metal oxides. The latter may be
either naturally occurring or in the form of gelatinous
precipitates or gels including mixtures of silica and
metal oxides. Use of a material in conjunction with the
present catalyst tends to improve the conversion and/or
selectivity of the catalyst in ~ertain organic conversion
processes. Inactive materials suitably serve as diluents
to control the amount of conversion in a given process so
that products can be obtained economically and in an
orderly manner without employing other means for control-
ling the rate of reaction. Normally, zeolite materials
have been incorporated into naturally occurring clays,
e.g., bentonite and kaolin, to improve the crush strength
of the catalyst under commercial operating conditions.
These materials, i.e., clays, oxides, etc., function as
binders for the catalyst. It is desirable to provide a
catalyst having good crush strength, because in a
petroleum refinery the catalyst is often subjected to
rough handling, which tends to break the catalyst down
into powder-like materials which cause problems in pro-
cessing. These clay binders have been employed for the
purpose of improving the crush strength of the catalyst.
Naturally occurring clays which can be ~om-
posited with the crystalline silicate/aluminosilicate
include the montmorillonite and kaolin family, which
families include the sub-bentonites, and the kaolins
commonly known as Dixie McNamee-Georgia and Florida clays
or others in which the main mineral constituent is
~ s77465
01 -15-
halloysite, kaolinite, dickite, nacrite, or anauxite.Such clays can be used in the raw state as originally
05 mined or initially subjected to calcination, acid
treatment or chemical modification.
In addition to the foregoing materials, the
materials of my invention can be composited with a porous
matrix material such as silica-alumina, silica-magnesia,
silica-zirconia, silica-thoria, silica-beryllia, silica-
titania as well as ternary compositions such as silica-
alumina-thoria, silica-alumina-zirconia, silica-alumina-
magnesia and silica-magnesia-zirconia. The matrix can be
in the form of a cogel. The relative proportions of the
finely divided crystalline aluminosilicate containing the
aluminum-rich outer shell and inorganic oxide gel matrix
vary widely with the crystalline aluminosilicate content
ranging from about 1 to about 90 percent by weight and
more usually, particularly when the composite is prepared
in the form of beads in the range of about 2 to about 50
percent by weight of the composite.
For most catalytic applications, it is preferred
that the crystalline silicate be free of basic metals
which tend to neutralize its active sites. The usual
basic metals found in the zeolites are alkali metals,
especially sodium, which are used in the hydrothermal
reaction mixture. For most applications known to the art
to be catalyzed by acidic zeolites, the alkali metal
content is preferably less than 0~1~ by weight, more
preferably less than O.Q3%, and most preferably less than
about 0.01% by weight. For a few unusual, nonacidic pro-
cesses, such as the formation of benzene from C7 alkanes,
for which a zeolite substantially free of acidity is
required, the alkali metal content is preferably high.
Employing the catalyst of this invention con-
taining a hydrogenation component, heav~f petroleum
residual stocks, cycle stocks, and other hydrocrackable
charge stocks can be hydrocracked at temperatures between
400F and 850F using molar ratios of hydrogen to hydro-
~o carbon charge in the range between 2 and ~0. The pressure
, 9~7~65
01 -16-
employed will vary between 10 and 2,500 psig and the
liquid hourly space velocity between 0.1 and 10.
05 The crystalline silicate/aluminosilicates of
this invention can be used for catalytic dewaxing either
in the presence or the absence of hydrogen, and at high or
low pressures. Catalytic particles containing these mate-
rials can also be use~ to stabilize hydrocracked lube oil
stocks to photolytic oxidation.
Employing the catalyst of this invention for
catalytic cracking, hydrocarbon cracking stocks can be
cracked at contact times of from 0.1 to 10 seconds, a
temperature between about 55nF and 1300F, a pressure
between about atmospheric and a hundred atmospheres.
Employing a catalytically active form of a
member of zeolites of this invention containing a hydro-
genation component, reforming stocks can be reformed
employing a temperature between 700F and 1000F. The
pressure can be between 100 and 1,000 psig, but is prefer-
ably between 200 and 700 psig. The liquid hourly space
velocity is generally between 0.1 and 10, preferably
between 0.5 and 4 and the hydrogen to hydrocarbon mole
ratio is generally between 1 and 20, preferably between
and 12.
The catalyst can also be used for hydroisomeri-
zation of normal paraffins, when provided with a hydro-
genation component, e.g., platinum. Hydroisomerization is
carried out at a t~mperature between 200F and 700F,
preferably 3nOF to 550F, with a liquid hourly space
velocity between 0.1 and 2, preferably between 0.25 and
0.50 employing hydrogen such that the hydrogen to hydro-
carbon mole ratio is between 1:1 and 5:1. Additionally,
the catalyst can be used for olefin isomerization employ-
ing temperatures between 30F and 500F.
The catalysts of my invention are particularly
useful in olefin polymerization reactions where the core
crystalline silicate polymerizes lower alkyl olefins such
as propene and butene to longer, straight or slightly
branched chain olefins, while the outer, more active
01 -17-
' ~7~
aluminosilicate shell can catalyze the further polymeri-
zation of the lower alkyl olefins with the longer chains
05 produced by the core. The result is even larger, multiply
branched long chain olefins. Further, because of the
controllable depth of the outer shell, both long and
branched chain olefins can be polymerized without having
to fit completely within the pore structure to reach the
catalytic sites. Further, the aluminosilicates produced
are relatively large, and easy to produce and filter.
Because most of the acid sites are near the outer surface,
the zeolites enhance reactions which are limited by diffu-
sion, e.g., polymerization of large olefins.
Example
A crystalline silicate according to my invention
is prepared using the following procedure: Dissolve 2.3 g
NaNO3 in 10 ml H2O. Put 100 g of 25~ tetrapropyl ammonium
hydroxide solution in a polyethylene beaker and add the
NaNO3 solution with rapid stirring. While stirring, add
40 g Ludox*AS-30 (30~ silica). Then add 60 g of crystal-
line silicate seeds prepared according to U.S. 4,061,724,
followed by a solution of 2.1 g Al(NO3)3.9H2O in 10 ml
H2O. Adjust the pH to 12.0 with concentrated HCl. Pour
the reaction mixture into a teflon bottle and put in a
stainless steel autoclave for 10 days at 100C. Cool and
remove the bottle. Filter and water-wash the product and
dry it overnight in a vacuum oven at 120C under 10" N2.
Calcine 8 hours at 450C. The product particles have a
crystalline silicate core having a silica:alumina mole
ratio of greater than 200:1 surrounded by an alumina con-
taining outer shell having a silica:alumina mole ratio of
less than 100:1. The crystal lattice structure of the
particles is uniform.
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