Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
:L2~29~
ACTIVATION OF ZEOLITES
BACKGROUNO OF THE IN\/I~NT ION
~ Fiel~ of the Invention
This invention relates to a method for enhancing the acid
activity of certain synthetic porous crystalline zeolites, including
high silica-containing synthetic crystalline materials, which involves
the sequential steps of reacting the crystalline material with
hydrogen ~luoride, contacting the hydrogen fluoride reacted material
lo with aluminum chloride vapor, treating the aluminum chloride ccntacted
material by contact with a solution of an a~monium salt or by
ammonolysis and calcining the resulting material. The resulting
zeolite composition exhibits enhd"ce~ Bronsted acidity.
Cescr;~tion of Prior Art
Zeolitic materials, both natural and synthetic, have been
demonstrated in the past to have catalytic properties for various
types of hydrocarbon con~ersions. CeItain zeclitic materials are
ordered, porous crystalline aluminosilicates having a definite
crystalline structure within which there are a large number of ~ er
cavities which may be interconn2cted by a number of still smaller
channels. Since the dimensions of these pores are such as to accept
for adsorption molecules of certain dimensions while rejection those
of larger dimensions, these materials have come to be known as
"~olecl~lar sieves" and are utilized in a variety of ways to take
advantage of these properties.
--2--
Such molecular sieves, both natural and synthetic, include a
~ide variety of positi~/e ion-containing cr~st311ine aluminosilicates.
These aluminosilicates can be described as a risld thrse-dimensional
framewor~ SiO4 and A10,~ ln ~hich the tetlahedra are cross-linked
~y the sharing o~ oxygen atoms ~hereby the ratio of the total ~l~minum
and silicon atoms to oxygen is 1:~. The electrovalenco or the
tet~ahedra con~aining al~minum is balanced by the inclusion in the
crystal of a cation, for example, an alkal metal or an alkaline ea~th
metal cation. This can be express2d wherein the ratio of aluminum to
the number of various cations, such as Ca/2, Sr/2, Na, K or Li is
e~ual to unity. ~ne type of cation may ~e exchanged either entirely
or partially by another t~/pe of cation utiliz~ng ion exchange
techniques in a conventional manner. By means o~ such cation
exchange, it has been possible to vary the ~roperties of a given
1~ aluminosilicate 3y suitable selection of the cation. rhe spaces
between the tetrahedra are occupied by molecules of ~atsr prior to
dehydration.
Prior art techniques have result~d in the formation of a
great variety of synthetic aluminosilicates. T~ese aluminosilicates
haye come to be designated by convenient symools, as illustrated by
zeolite ZSM-5 (U.S. Patont 3,102,886).
High silica-containing synthetic zeolites are well known in
the art and it is generally accepted that the ion exchange capacity of
the crystalline zeolite is directly dependent on its alLminum
content. Thus, lor example, the more aluminum there is in a
crystalline structure, the more cations are required to balance the
electronegativity thereof, and when such cations are o~ the acidic
type such as hydIogen, they imoart tremendous catalytic activity to
the crystalline material. ûn the other hand, high silica-containing
zeolites having little or substantially no aluminum, have many
important properties and characteristics and a high degree o~
structural stability such that they have become candidates ~or use in
various processes Lncluding catalytic processes. ,~aterials o~ this
type are known in the art and include high silica-containing
aluminosilicates sucn as ZSM-5, ZSM-ll (U.S. Patent 3,709,979), and
ZSM-12 (U.S. Patent 3,832,449) to mention a few.
_3_ 1
The silica-to-alumina ratio or a given zeolite is often
variable; 'or example, zeolite X (U.S. Patent 2,882,244) can be
synthesized with a silica-to-alumina ratio of from 2 ~o 3; zeolitl~ Y
(U.S. Patem ~,130,007) from 3 to about 6. In som2 zeolites, the
; upper limit OT silica-to-alumina ratio ls virtually unbounded.
Zeolite ZSM-5 is one such material wherein the silica-to-alLImina ratio
is at least 5. U.S. Patent 3,941,371 discloses a crystalline metal
organo silicate essentially free of al minum and ~xhibiting an x-ray
diffraction oatt~rn characteristic of ZSM-5 type aluminosilicate.
U.S. ~atents 4,û61,724; 4,073,36~ and 4,104,294 describe microporous
crystalllne silicas or organo silicat~s ~her_in the aluminum content
present is at impurity levels.
Because of the extremely low aluminum content of these high
silica-containing synthetic zeolites, t.~elr ion exchange capacity is
l; not as gre~t as mate~ials with a hisher aluminum content. Ther2~0re,
when these materials are contacted with an acidic solution and
thereafter aro process2d in a conventional manner, they ar~ not as
catalytically active as their higher aluminum-containing counterparts.
rhe novel process of this invention permits the prepa~ation
of certain synthetic high silica-containing materials which have all
the desirable properties ln~erently possessed by such high silica
materials and, yet, have an acid activity which heretofore has only
been pos-sihle to be achieved by materi~l~ having a higher aluminum
content in their "as synthesi~ed" form. It ~urther permits valuable
~, activation of crystalline zeolites having much lower silica-to-alumina
mole ratios.
It is noted that U.S. Patents 3,354,078 and 3,~44,220 relate
to treating crystalline aluminosilicates with volatile metal halides.
Neither of these latter patents is, however, concerned with treatment
of crystalline materials having a high silica-to-alumina mole ratio or
with treatment of any crystalline zeolite with hydrogen ~luoride in
the present manner. In fact, the use of hydrogen fluoride ~ith
aluminosilicates has been aYoided because of resulting lattice
damage Hydrogen fluoride in high concentrations, e.g. 5 N or
greater, readily attacks both silica and al~mina. Lower
concentrations may also damage lattice structures if contact is
~¢34~Z~ L~
maintained r~or too long a time. ~ith some zeolitic materials,
hydrosen rluoride tre7tment under controlled conditions has been used
to alter pore si2e. U.S. ?atents 3,997,474 and 4,û54,511 relate to
altering e~fective pcre si7e of ~atural rerrierite ore with very
dilute hydrogen fluoride t eatment. However, the same treatment of
erionite resulted in a large loss in activity and crystallinity.
SUMMARY ûf T~E INV~TION
The present lnvention relates to a novel process for
improving acid activity of certain synthetic crystall.ine
aluminosilicate zeolltes having been synthesized rrom reaction
mixtures containin~ a diamine as a cation source, ineluding high
silica-containing synthetic crystalline zeolites, which comprises the
sequential steps of reacting the zeolite ~ith a dilute aqueous
solution or hydrogen f'uoride (e.g. less ~han about 1.5 weight pe~cent
l~ HF) for a time or less than about one hour, contacting the hydrogen
fluoride react2d zeoli.e ~ith aluminum chloride vapor~ treating the
aluminum chloride contacted zeolite ~y contact with an ammonium salt
solution or by ammonolysis, and calcining ~he resulting material. The
resulting calcined material exhibits enhanced 3ronsted acidity ~nd,
~0 theIefore, improved acid activity toward catalysis o~ nume~ous
chemical reactions, such as, for example, crac~ing of organic, e.g.
hydrocarbon t compounds.
oEs~RIprIûN Of SPFCIFIC ~eCOI~ENTS
The novel process of this invention is concerned ~ith the
2i treatment of certain synthetic porous crystalline zeolites, including
high silica-containins synthetic c~ystalline material. The expression
"hi~h silica-containin~ orystalline material'' is intended to derine a
crystalline structure ~hich has a silica-to-alumina ratio greater than
100 and more preferably greater than SCO, up to and including those
highly siliceous mate~ials ~here the silica-to-alumina ratio is
infinity or as reasonably close to infinit~J as practically possible.
This latter group of highly siliceous mate~ials is exemplified by
U.S. patents 3,941,871; 4,û61,724; 4,07~,865 an~ 4,1Q4,~54 wherein
the materials are prepared ~rom reaction solutions ~hich involve no
4j deliberate addition of aluminum. However, trace ~uantities of
aluminum are usually present due to the impurity of the synthesis
~1 2V~
-
reaction soluticns. It is to be unders~30d that the expression ~high
silica-containing crystalline material" alsa specifically includes
those materials ~nioh have other metals besides silica and/or alumina
assorjated therewith, such as boron, lron, chromium, etc. Thus, the
starting materials utilized in the nûvel procoss of this invention may
havc a silica-to-alumina ratio greater than about 100 (irrespe~ive of
what other materials or metals are pres2nt in the crystal structure).
The synthetic zeolite starting materials utilized herein,
including those having a silica-to-alumina mole ratio g~eater than
about lûO, are synthesi~ed from reaction mixt~res containing diamines
as cation sources. Zeolites prepared ~ith other sources of cations in
the reaction mixture may be activated by exposure to aluminum halide
vapor at elevated temperature. ~owever, zoolites synthesi~ed from
rPaction mixtures containing diamines as ca~ion sources ~ill not be
1, activated by such a method as hereinafter exemplified. The pres2nt
me~hod sisnificantly activates such ~eolito materials as ~ill also be
exemplified. i~or-limiting examples af diamines used as cation sources
in zeolite synthesis reaction mixtures lnclude C4 to C10 diamines,
e.g. l,S-diaminopentane.
The novel proc~ss o~ this inveniion is simple and ~asy to
carry out althou~h tne results theref-om are d~amatic. It is c~rried
out by reacting the zeolite with a dilute aqueous solution cf hy~rogen
fluoride o~ rrom about 0.1 to about ~ Normal, said re3ction being
conducted at a temperature of from about 0C to about 30C, pr~ferably
at a~cut amoient temperature, for a time of less than a~out 60
minutes, preferably from about 5 minutes to less than about 60
~inutes. The hydrogen fluori~e reacted zeolite is washed, usually
with cold ~Nater, dried, usually ~y heating to about 130qC, and then
contacted with volatile aluminum chloride at a t~mperature of from
a~out lCOqC ta about 850qC, prefeIably from about 100CC to about
550~C. The aluminum chloride contacted zeolite iâ dried, again
usually by heating to about 130qC, and contacted with an ammonium salt
solution, e.g. lN NH4N03, or ~ith ammonium hydroxide or ammonia,
and thereafter calcined at a temperature of from about 200C to about
600C in an inert atmosphere of air, nitrogen, etc. at subatmospheric,
atmospheric or superatmospheric pressures for from about 1 minute to
about 48 hours.
~29i~
--6--
The amount of hydrogen fluoride which is utilized in the
process of this invention is from about 0.02 to about 0.2 grams of
hydrogen fluoride per gram of crystalline zeolite material being
treated.
The ammonium salt solution contacting step may be conducted
for a period of time of from about 1 hour to about 20 hours at a
temperature of from about 0C to about goaC. The ammonium salt used
is not narrowly criticai and will normally be an inorganic salt such
as ammonium nitrate, ammonium sulfate, ammonium chloride1 etc. If the
ammonium salt solution is aqueous, it will be from about 0.1 to about
5 Normal, preferably about 1 Normal.
If instead of contacting the aluminum chloride contacted
zeolite with an ammonium salt solution, ammonolysis is conducted, the
zeolite will be contacted with 0~1 to 5 Normal ammonium hydroxide at a
temperature of from aoout 0C to about 90C for a time of from about 1
hour to about 20 hours, or ~ith moist or dry gaseous ammonia at a
temperature of from about 50C to about 200C for a time of from about
10 minutes to about 2 hours.
Of the zeolite materials having been synthesized from a
reaction mixture containing a diamine as a cation source
advant~g~olJsly treated in accordance herewith, zeolites ZSM-5, ZSM-ll,
ZSM-35 and ZSM-48 are particularly noted. ZSM-5 is
described in U.S. 4,139,600, ZSM-ll is described in U.S.
Patent 4,108,881. ZSM-35 is described in U.S. 4,016,245
and 4,107,195.
Z5M-48 can be identified, in terms of moles of anhydrous
oxides per 100 moles of silica as follows:
(0.05 to 5) N20: (0.1 to lO)M2/nO : (0 to 4)A1203 : (lOO)SiO2
wherein M is at least one cation having a valence n, N is a mixture of
a C2-C12, and mcre preferably of a C3-C5, alkylamine and a
tetramethylammonium compound and wherein the composition is
characterized by the distinctive X-ray diffraction pattern as shown
below:
_7_ ~2~2~
Characteristics Lines of Zeolite Z5~ 8
d _ Relative Intznsity (I/Io)
11.8 + 0.2 S
10.2 ~ 0.2
7.2 + 0.15 W
4.~ + 0.08 VS
3.9 + 0.08 VS
-
3.6 + 0.06 ~
3.1 + 0.05 W
2.85 + 0 05 ,~
These values were determined by standard techniques. The
radiation ~as the K-alpha dcublet of copper, and a diffractometer
e~uipped with a scintillation counter and a strip chart oen recorder
~as uszd. The pea~ heights, I, and the positions as a function of two
l; ti~es theta, where theta is the 8ragg angle, wer r~ad from the
spect m met~r chart. From these, the relative intensities, 100 I/I
where Io is the intensit~ of the st~onge~t line or peak, and d
(obs.), the interplanar spacing in Angstroms (A) corTesponding to the
recorded lines, were calculated. In the fore~oing table the relative
intensities are given in terms of the symbols W = weak, VS = very
strong, M = medium and W~ eak-to-medium (depending on the cationic
form). Ion exchange o~ the sodium ion ~ith cations reveals
suhstantially the same pattern with 33me minar shift, in interplanar
spacing and va~iation in relative intensity. Other minor variations
can occur depending on the sillcon to aluminum -atio of the particular
sample, as well as if it has been subjected to thermal tTeatment.
ZSM-48 can be prepared from a reaction mixture containing a
sourc~ of silica, tetramethylammonium compound, C2-C12 alky!amine,
an alkali metal oxide, e.g. sodium, with or without a source of
alumina, and water, and having a comoosition, in terms of mole ratios
of oxides, falling ~ithin the following ranges:
~EACTANT5 BROAD YKt~ tK~
A1203/SiO2 0 to O.OS 0 to 0.02
Na20/SiO2 0.01 to 1.0 0.1 to 0.5
N2o/sio2 0.005 to 0 5 0.005 to 0.25
OH /SiO2 0.01 to 0.5 0.05 to 0.2
H20/Sio2 10 to 2ûO 20 to 100
where-n N is a mix~ure of a C2-~12 alkylamine and tetramethyl-
ammonium compound, and maintaining the mixture at 8C-2~0CC until
crystals o~ Z~M-48 are formed.
he molar ratio or C2-C12 alkylamine to tetramethyl
ammonium compound is not narrowl~ critical and can range from L:1 to
10:1. The tetrame~hylammonium compound can include t,~e hydroxide or
halide ~ith the chloride being particular-y preferred.
The original cations o~ ZSM-48 can ~e replaced, at least in
part, by calcination and/or ion exchange ~ith another cation ~hus,
the original cations are exchanged into a hydrogen or hydrogen ion
precursor form or a form in whicn the original cation has been
replaced by a metal or Groups ~I through VII~ of the Poriodic Table.
Thus, for example, it is contemplated that ~he original cations can be
r~pla~ad with ammonium ions or with hydronium ions. Catalytically
l; active forms of thes2 ~ould include, in p~Iticular, hydrcgen, rar~
earth metals, aluminum, metals of Groups II and VIII of the Periodic
Table and manganese.
The activity en~anced materials propa~ed oy the present
orocess are useful as catalyst componentâ for acid catalyz~d organic
~o compourd conversion reactions. 5uch reactions include, as
n~n-limiting examples, crac~ing of hydrocar~ons, wherein the reaction
conditions lnclude a temperature o~ from acout 300C to about aoooc, a
pressure of from aoout 15 psia to about 5C0 psia, and a wei~ht hourly
space velocity of from about 0.1 to ahaut 20; and conversion o~
~S methanol to ~asoline wherein the reaction conditions include a
temperature of from about 300C to about 550C, a pressure of from
about 5 psia to about 5C0 psia, and a weight hourly space velocity of
from about 0.1 to abcut 100.
In practicing a particularly desi~ed chemical conversion
process, it may be useful to incûrporate the a~ove-described activity
enhanced matPrial with a matri~ comprising a material resistant to the
temperature and other conditions employed in the process. Such matri~
~aterial is useful as a birder and imparts additional resistance to
the catalyst for the severe temperature, pressure and reactant feed
stream velocity corditions encountered in many cracking processes.
_9_
Useful matrix materials include both synthetic and naturally
occurring substances, as ~ell as inorganic materials such as clay,
siLica anc/or metal oxides. The latter may be either naturally
occurring or in the form of gelatincus precipitat3s or gels inclu~ing
mixtures of silica and metal oxides. ,~aturally occurring clays which
can be composi~ed with the zeolite include those of the
montmorillonite and kaolin families, which r^amilies include the
sub-~entonites and the kaolins commoniy known as Oixie, McNamee,
Georgia and florida clays or others in wnlch t~e main mineral
constituent is halloysite, kaolinits, dickite, nacrite or anauxite.
Such clays can be used in the raw state as originally mined or
initially subjected to calcination, acid treaL",en~ or chemical
modi~ication.
In addition to the foreqoing mairix materials, the catalys-
~mployed herein may oe co~co-~ited with a ma erial such as alumina,
i, silica-alumina, silica_~agnesia, silica-zirconia, silica-thoria,
silica-beryllia? and silica-titania, as well as ternary compositions,
âuch as silica-alumina-thoria, silica-alLmina-zirconia,
silica alumina-ma~nesia and silica-nagnesia-zi~ccnia. The matrix may
oe in the form o~ a cosel. The relative procorti3ns o~ activity
~o enhanced zeolite co",ponent and matrix, on an anhyd~ous hasis, may vary
widely with the zPolite content ranging r^rom aoout 1 to about 99
percent by weight and more usually in the range of aoout 5 to about 80
percent by weisht of the total dry com~osite.
The following examples will illustrate the novel method or
the present invention.
E~ E
A six gram quantity o~ zeolite ZSM-48 ~as synthesized as
above indicated witn the reaction mixture containing 1,5 -
diaminopentane as the source of cations. The zeolite product had a
silica-to-alumina mole ratio of 870. It was calcined at 538~C for one
hour with helium rlow and for ~our hours in air.
\
29'1~
-10-
~XPMfLE 2
A 4.5 gram portion or the calcined zeolite ZSM-4~ from
~xample 1 was reacted ~ith S0 ml of 1 percent (0.5N~ hydrogen fluoride
solution for ten ~inutes at 20CC and then ~ater ~asned ~ith cQld
; water. The hydrogen ~luoride reacted zeolite was dried at about 1303C
and then contacted ~ith !~ aqueous solution of NH4N03 (no aluminum
chloride contacting) for 4 hours at ~o~r and calcined at 5380 in air
for 6~ minutes.
FXAMPL~ 3
A l.S gram portion of the calcined zeolite Z~-48 from
Example 1 l~as reactod ~ith 50 ml o~ 1 percont (a.5N) hydrogen fluoride
solution for ten minutes at 2û~C and then ~ater washed with cold
~ater. The hyd~ogen fluoride reacted zeolito was dried at about 130CC
and loaded into a glass tube ~ith 3 grams of an~ydrous aluminum
lS chloride on the upstream end. The tube ~Nas heated slowly (about 2CC
~er minute) ,rom lûO~C to 550~C with helium flo~ing at abcut 20
ml/minute. This caused aluminu~ chloride vapor to pass through the
zeolitP for about 240 minutes. The aluminum chloride c~ntacted
zeolite was remoYed rrom tne tube, dried at about L30C, ~reated with
lN ~H~N03 and calcined as in Exa~ple 2.
ExaM Q E 4
rhe final products of xamples 2 and 3 ~ere subje~tod to the
Alpha Test to ~easuIe catalytic actiY-ty. As is known in the art, the
Alpha Value is an ap,oroximate indication of the catalytic cracking
activity of the catalyst compaIed to a standard catalyst and it gives
the relative rate constant (rate of normal hexane conversion per
volume of catalyst per unit time). It is based on the activity of the
highly active silica-al~mina crac~ing catalyst taken as an Alpha of 1
(rate constant = 0.016). The Alpha Test is described in U.S. Patent
3,354,078 and in The Journal of Catalysis, Vol. IV, pp. 522-529
(August 1965). The results of this test are listed below:
Product of T~e~L~ nL
Example ~ Calcination Alpha Vaiue
2 Hf+NH4N03 4.4
3 ~f+AlC13~NH4N03 13
cX~M~c ~
A sample ~f zeolite Z~M-48 was synthesized as above indicated
~ith the reaction mixture containing 1,8-octanedi~mine as the cation
source. This zeolite product had a sillca-to-alumina mole ratio of
; 180. It ~as calcined as in Example 1.
EX~ Q 6
An aliquot or the zeol.ite product of xample 5 ~as contacted
~ith lN NH4i~03 for 18 hours at 20qC (no hydrogen fluoride or
aluminum cnlor~de tr~atment) and then calrined as in ~xample 1.
EXAMPL' 7
Another aliquot of the Example ~ zeolite product ~!~as contacted
~ith aluminum chloride Yapor as in Example 3 (no hydrogen ~luoride
treatment), dried at about L30C, treated ~ith lN NH4N03 and
calcined as in Examole 3.
EXAMFLF 8
A quantity of the product of 'cxamDle 7 was reacted with 40 ml
of 1 perc~nt (0.5N) hydrogen fluoride solution for ten minutes at 20~C
and then washed with cold water. It ~as then treated with lN
NH4N03 as in E~ample 3 ~no aluminum chloride treatment subs~quent
to hydrogen fluoride tr~atment), ~ashed~ dried and calcined for 30
minutes at ~38aC in air.
EXAMPLE 9
A quantity o~ product of ~xample 7 was treated with hydrogen
fluoride as in ExamDle 8 and washed with ~Nat2r. It was then, however,
oontacted with aluminum chloride, contacted with NH4N03 and
calcined as in Example 3.
EXAMFLE lû
Quantities of the final products of Examples 5, 6, 7, 8 and 9
were subjected to ~he Alpha Test. The ~esults of this test are listed
below:
Product of ~reatment Alpha
ExamDle + Calcination Value
(base) less than 1
6 NH41~03 31
7 AlC13+NH4No3 30
8 cx.7~HF+NH4N03 28
; 9 Cx.7+~F+AlC13~NH41~03 65
-12-2~ ~
All o~ the above experlments demonstrate that there is a
respons2 to the alLminum chloride treatment for these zeolites having
be~n prepa~ed from a reaction mixtu~e ccntaining a diamine as the
cation source only ~ren a hyd~ogen fluoride treatment st~p prec~des
the aluminum chloride treatment step. Note Ln 'xample 9 that the
zeolite not previously activated ~y cont ct ~ith alLminum chloride
(Examplo 7) was substantially activated wnen it ~as treated with
hydrogen fluoride prior to al~minum chl3rlde 'reatment.
