Catalysis over activated zeolites

A process is provided for conducting organic compound conversion over a catalyst comprising a high silica crystalline zeolite which has been treated by contact with aluminum chloride vapor.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a process for conducting organic compound 
conversion over a catalyst comprising a crystalline zeolite, including a 
high silica-containing crystalline material, which has been treated by 
contacting said zeolite with aluminum chloride vapor, followed by 
hydrolysis and calcination. 
2. Description of Prior Art 
Zeolitic materials, both natural and synthetic, have been demonstrated in 
the past to have catalytic properties for various types of hydrocarbon 
conversions. Certain zeolitic materials are ordered, porous crystalline 
aluminosilicates having a definite crystalline structure within which 
there are a large number of smaller cavities which may be interconnected 
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 
rejecting those of larger dimensions, these materials have come to be 
known as "molecular sieves" and are utilized in a variety of ways to take 
advantage of these properties. 
Such molecular sieves, both natural and synthetic, include a wide variety 
of positive ion-containing crystalline aluminosilicates. These 
aluminosilicates can be described as a rigid three-dimensional framework 
of SiO.sub.4 and AlO.sub.4 in which the tetrahedra are cross-linked by the 
sharing of oxygen atoms whereby the ratio of the total aluminum and 
silicon atoms to oxygen is 1:2. The electrovalence of the tetrahedra 
containing aluminum is balanced by the inclusion in the crystal of a 
cation, for example, an alkali metal or an alkaline earth metal cation. 
This can be expressed wherein the ratio of aluminum to the number of 
various cations, such as Ca/2, Sr/2, Na, K or Li is equal to unity. One 
type of cation may be exchanged either entirely or partially by another 
type of cation utilizing ion exchange techniques in a conventional manner. 
By means of such cation exchange, it has been possible to vary the 
properties of a given aluminosilicate by suitable selection of the cation. 
The spaces between the tetrahedra are occupied by molecules of water prior 
to dehydration. 
Prior art techniques have resulted in the formation of a great variety of 
synthetic aluminosilicates. These aluminosilicates have come to be 
designated by convenient symbols, as illustrated by zeolite ZSM-5 (U.S. 
Pat. No. 3,702,886). 
The use of certain zeolites as catalyst components is taught in U.S. Pat. 
No. 4,305,808, for example. 
High silica-containing 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 aluminum content. Thus, for 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 of the acidic type such as hydrogen, they impart tremendous 
catalytic activity to the crystalline material. On the other hand, high 
silica-containing zeolites having little or substantially no aluminum, 
have many important properties and characteristics and a high degree of 
structural stability such that they have become candidates for use in 
various processes including catalytic processes. Materials of this type 
are known in the art and include high silica-containing aluminosilicates 
such as ZSM-5, ZSM-11 (U.S. Pat. No. 3,709,979), and ZSM-12 (U.S. Pat. No. 
3,832,449) to mention a few. 
The silica-to-alumina ratio of a given zeolite is often variable; for 
example, zeolite X (U.S. Pat. No. 2,882,244) can be synthesized with a 
silica-to-alumina ratio of from 2 to 3; zeolite Y (U.S. Pat. No. 
3,130,007) from 3 to about 6. In some zeolites, the upper limit of 
silica-to-alumina ratio is virtually unbounded. Zeolite ZSM-5 is one such 
material wherein the silica-to-alumina ratio is at least 5. U.S. Pat. No. 
3,941,871 discloses a crystalline metal organo silicate essentially free 
of aluminum and exhibiting an x-ray diffraction pattern characteristic of 
ZSM-5 type aluminosilicate. U.S. Pat. Nos. 4,061,724; 4,073,865 and 
4,104,294 describe microporous crystalline silicas or organo silicates 
wherein the aluminum content present is at impurity levels. 
Because of the extremely low aluminum content of these high 
silica-containing zeolites, their ion exchange capacity is not as great as 
materials with a higher aluminum content. Therefore, when these materials 
are contacted with an acidic solution and thereafter are processed in a 
conventional manner, they are not as catalytically active as their higher 
aluminum-containing counterparts. 
The novel process of this invention permits the preparation of certain high 
silica-containing materials which have all the desirable properties 
inherently possessed by such high silica materials and, yet, have an acid 
activity which heretofore has only been possible to be achieved by 
materials having a higher aluminum content in their "as synthesized" form. 
It further permits valuable activation of crystalline zeolites having much 
lower silica-to-alumina mole ratios. 
It is noted that U.S. Pat. Nos. 3,354,078 and 3,644,220 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 of at least 100 which 
have been synthesized from a forming solution containing quaternary onium 
cations. 
SUMMARY OF THE INVENTION 
The present invention relates to a novel process for converting organic 
compounds over a catalyst comprising a zeolite of altered activity 
resulting from treating the zeolite in a special way. The treatment 
requires sequentially calcining the synthesized crystalline material under 
appropriate conditions, contacting the calcined material with aluminum 
chloride vapor under appropriate conditions, hydrolyzing the aluminum 
chloride contacted material and contacting the hydrolyzed material under 
appropriate conditions. The resulting zeolite material exhibits enhanced 
activity toward catalysis of numerous chemical reactions, such as, for 
example cracking of organic, e.g. hydrocarbon, compounds. 
DESCRIPTION OF SPECIFIC EMBODIMENTS 
This application is a continuation-in-part of application Ser. No. 319,175, 
filed Nov. 9, 1981, now U.S. Pat. No. 4,438,215, incorporated herein in 
its entirety by reference. The expression "high silica-containing 
crystalline material" is intended to define a crystalline structure which 
has an initial silica-to-alumina mole ratio greater than about 100, and 
more preferably greater than about 500, up to and including those highly 
siliceous materials where the initial silica-to-alumina mole ratio is 
infinity or as reasonably close to infinity as practically possible. This 
latter group of highly siliceous materials is exemplified by U.S. Pat. 
Nos. 3,941,871; 4,061,724; 4,073,865 and 4,104,294 wherein the materials 
are prepared from reaction solutions which involve no deliberate addition 
of aluminum. However, trace quantities of aluminum are usually present due 
to impurity of the reaction solutions. It is to be understood that the 
expression "high silica-containing crystalline material" also specifically 
includes those materials which have other metals besides silica and/or 
alumina associated therewith, such as boron, iron, chromium, etc. 
The zeolite starting materials utilized herein, including those having an 
initial silica-to-alumina mole ratio greater than about 100, may be 
prepared from reaction mixtures containing sources of various quaternary 
anium cations. The present process provides noted improvement regardless 
of which quaternary cation sources are present in said reaction mixtures. 
Non-limiting examples of cation sources to be used in the manufacture of 
the zeolite starting materials include onium compounds having the 
following formula: 
EQU R.sub.4 M.sup.+ X.sup.- 
wherein R is alkyl of from 1 to 20 carbon atoms, heteroalkyl of from 1 to 
20 carbon atoms, aryl, heteroaryl, cycloalkyl of from 3 to 6 carbon atoms, 
cycloheteroalkyl of from 3 to 6 carbon atoms, or combinations thereof; M 
is a quadricoordinate element (e.g. nitrogen, phosphorus, arsenic, 
antimony or bismuth) or a heteroatom (e.g. N, O, S, Se, P, As, etc.) in an 
alicyclic, heteroalicyclic or heteroaromatic structure; and X is an anion 
(e.g. fluoride, chloride, bromide, iodide, hydroxide, acetate, sulfate, 
carboxylate, etc.). When M is a heteroatom in an alicyclic, 
heteroalicyclic or heteroaromatic structure, such structure may be, as 
non-limiting examples, 
##STR1## 
wherein R' is alkyl of from 1 to 20 carbon atoms, heteroalkyl of from 1 to 
20 carbon atoms, aryl, heteroaryl, cycloalkyl of from 3 to 6 carbon atoms 
or cycloheteroalkyl of from 3 to 6 carbon atoms. 
The process of treating the zeolite for use herein is simple and easy to 
carry out although the results therefrom are dramatic. The process 
involves calcining a high silica crystalline material having a silica to 
alumina ratio of at least 100 and preferably of at least 500 which has 
been prepared from a reaction mixture containing quaternary onium ions by 
heating the same at a temperature within the range of from about 
200.degree. C. to about 600.degree. C. in an atmosphere such as air, 
nitrogen, etc. and at atmospheric, superatmospheric, or subatmospheric 
pressure for from about 1 minute to about 48 hours. The calcined zeolite 
is thereafter contacted with aluminum chloride vapor, preferably admixed 
with an inert gas such as nitrogen, at a temperature ranging from about 
100.degree. C. to about 600.degree. C. The amount of aluminum chloride 
vapor which is utilized is not narrowly critical, but usually 0.01 to 1 
gram and preferably about 0.5 gram of aluminum chloride is used per gram 
of high silica crystalline material. Following the contact with aluminum 
chloride, the crystalline material is then hydrolyzed in water at a 
temperature ranging from about 20.degree. C. to about 100.degree. C., 
followed by a final calcination at a temperature ranging from about 
200.degree. C. to about 600.degree. C. although temperatures of from about 
450.degree. C. to about 550.degree. C. are preferred. 
Of the zeolite materials advantageously treated in accordance herewith, 
zeolites ZSM-5, ZSM-11, ZSM-5/ZSM-11 intermediate, ZSM-12, ZSM-23, ZSM-35, 
ZSM-38 and ZSM-48 are particularly noted. ZSM-5 is described in U.S. Pat. 
Nos. 3,702,886 and Re. 29,948, the entire contents of each being hereby 
incorporated by reference herein. ZSM-11 is described in U.S. Pat. No. 
3,709,979, the entire teaching of which is incorporated herein by 
reference. ZSM-5/ZSM-11 intermediate is described in U.S. Pat. No. 
4,229,424, the entire teaching of which is incorporated herein by 
reference. ZSM-12 is described in U.S. Pat. No. 3,832,449, the entire 
contents of which are incorporated herein by reference. ZSM-23 is 
described in U.S. Pat. No. 4,076,842, the entire teaching of which is 
incorporated herein by reference. The entire contents of U.S. Pat. Nos. 
4,016,245 and 4,046,859, describing ZSM-35 and ZSM-38, respectively, are 
incorporated herein by reference. ZSM-48 is described in U.S. Pat. No. 
4,397,827, the entire teaching of which is incorporated herein by 
reference. 
In general, organic compounds such as, for example, those selected from the 
group consisting of hydrocarbons, alcohols and ethers, are converted to 
conversion products such as, for example, aromatics and lower molecular 
weight hydrocarbons, over the activity enhanced crystalline zeolite 
prepared as above by contact under oganic compound conversion conditions 
including a temperature of from about 100.degree. C. to about 800.degree. 
C., a pressure of from about 0.1 atmosphere (bar) to about 200 
atmospheres, a weight hourly space velocity of from about 0.08 hr.sup.-1 
to about 2000 hr.sup.-1 and a hydrogen/feedstock organic compound mole 
ratio of from 0 (no added hydrogen) to about 100. 
Such conversion processes include, as non-limiting examples, cracking 
hydrocarbons to lower molecular weight hydrocarbons with reaction 
conditions including a temperature of from about 300.degree. C. to about 
800.degree. C., a pressure of from about 0.1 atmosphere (bar) to about 35 
atmospheres and a weight hourly space velocity of from about 0.1 to about 
20; dehydrogenating hydrocarbon compounds with reaction conditions 
including a temperature of from about 300.degree. C. to about 700.degree. 
C., a pressure of from about 0.1 atmosphere to about 10 atmospheres and a 
weight hourly space velocity of from about 0.1 to about 20; converting 
paraffins to aromatics with reaction conditions including a temperature of 
from about 100.degree. C. to about 700.degree. C., a pressure of from 
about 0.1 atmosphere to about 60 atmospheres, a weight hourly space 
velocity of from about 0.5 to about 400 and a hydrogen/hydrocarbon mole 
ratio of from about 0 to about 20; converting olefins to aromatics, e.g. 
benzene, toluene and xylenes, with reaction conditions including a 
temperature of from about 100.degree. C. to about 700.degree. C., a 
pressure of from about 0.1 atmosphere to about 60 atmospheres, a weight 
hourly space velocity of from about 0.5 to about 400 and a 
hydrogen/hydrocarbon mole ratio of from about 0 to about 20; converting 
alcohols, e.g. methanol, or ethers, e.g. dimethylether, or mixtures 
thereof to hydrocarbons including aromatics with reaction conditions 
including a temperature of from about 275.degree. C. to about 600.degree. 
C., a pressure of from about 0.5 atmosphere to about 50 atmospheres and a 
liquid hourly space velocity of from about 0.5 to about 100; isomerizing 
xylene feedstock components to product enriched in p-xylene with reaction 
conditions including a temperature from about 230.degree. C. to about 
510.degree. C., a pressure of from about 3 atmospheres to about 35 
atmospheres, a weight hourly space velocity of from about 0.1 to about 200 
and a hydrogen/hydrocarbon mole ratio of from about 0 to about 100; 
disproportionating toluene to product comprising benzene and xylenes with 
reaction conditions including a temperature of from about 200.degree. C. 
to about 760.degree. C., a pressure of from about atmospheric to about 60 
atmospheres and a weight hourly space velocity of from about 0.08 to about 
20; alkylating aromatic hydrocarbons, e.g. benzene and alkylbenzenes, in 
the presence of an alkylating agent, e.g. olefins, formaldehyde, alkyl 
halides and alcohols, with reaction conditions including a temperature of 
from about 340.degree. C., to about 500.degree. C., a pressure of from 
about atmospheric to about 200 atmospheres, a weight hourly space velocity 
of from about 2 to about 2000 and an aromatic hydrocarbon/alkylating agent 
mole ratio of from about 1/1 to about 20/1; and transalkylating aromatic 
hydrocarbons in the presence of polyalkylaromatic hydrocarbons with 
reaction conditions including a temperature of from about 340.degree. C. 
to about 500.degree. C., a pressure of from about atmospheric to about 200 
atmospheres, a weight hourly space velocity of from about 10 to about 1000 
and an aromatic ydrocarbon/polyalkylaromatic hydrocarbon mole ratio of 
from about 1/1 to about 16/1. 
In practicing a particularly desired chemical conversion process, it may be 
useful to composite the above-described activity enhanced crystalline 
zeolite with matrix comprising material resistant to the temperature and 
other conditions employed in the process. Such matrix material is useful 
as a binder and imparts additional resistance to the catalyst for the 
severe temperature, pressure and reactant feed stream velocity conditions 
encountered in many cracking processes. The composite may be in the form 
of an extrudate. 
Useful matrix materials include both synthetic and naturally occurring 
substances, as well as inorganic materials such as clay, 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. Naturally occurring clays which can be composited with the zeolite 
include those of the montmorillonite and kaolin families which include the 
subbentonites and the kaolins commonly known as Dixie, McNamee, Georgia 
and Florida clays or others in which the main mineral constituent is 
halloysite, kaolinite, dickite, nacrite or anauxite. Such clays can be 
used in the raw state as originally mined or initially subjected to 
calcination, acid treatment or chemical modification. 
In addition to the foregoing matrix materials, the catalyst employed herein 
may be composited with a porous matrix material such as alumina, 
silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, 
silica-beryllia, and silica-titania, as well as ternary compositions, such 
as silica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesia 
and silica-magnesia-zirconia. The matrix may be in the form of a cogel. 
The relative proportions of activity enhanced zeolite component and 
matrix, on an anhydrous basis, may vary widely with the zeolite content of 
the dry composite ranging from about 1 to about 99 percent by weight and 
more usually in the range of about 5 to about 80 percent by weight.

The following examples will illustrate the novel method of the present 
invention. 
EXAMPLES 1-5 
Four different high silica containing zeolites were used in this 
example--all of which were synthesized from reaction mixtures containing 
tetraalkylammonium ions. These included three crystalline materials having 
the x-ray diffraction pattern of ZSM-5, having initial silica-to-alumina 
mole ratios of 600, 2860 and about 50,000 respectively. One sample of a 
crystalline material having the x-ray diffraction pattern of ZSM-11 and 
having an initial silica-to-alumina mole ratio of about 1,056 was also 
utilized. 
The above as synthesized zeolites were calcined in either air or nitrogen 
at 1.degree. C. per minute to about 540.degree. C. where the temperature 
was maintained for about 10 hours. Two grams of each of the calcined 
zeolites were placed in a horizontal tube on one side of a fritted disc 
and one gram of aluminum chloride was placed on the other side. Dry 
nitrogen at 50-100 cc per minute was introduced from the direction of the 
zeolite while heating at 100.degree. C. for one hour. The direction of the 
nitrogen flow was then reversed and the temperature raised to 500.degree. 
C. at 2.degree. C. per minute and maintained at 500.degree. C. for 1/2 
hour. After cooling the zeolite was transferred to another reactor and 
again heated to 500.degree. C. in nitrogen to remove any residual 
unreacted aluminum chloride. 
Each of the four zeolites was then hydrolyzed at 100 ml of water at room 
temperature for at least two hours. The hydrolyzed samples were filtered, 
washed well with water, air-dried, and then finally calcined at 
540.degree. C. for ten hours. 
The results obtained, as well as the properties of the activity enhanced 
zeolites are shown in Table I. 
As can be seen, the alpha value of each of the five zeolites was 
considerably increased in accordance with the activation method. 
Furthermore, this enhanced acid activity was clearly intrazeolitic as 
evidenced by the shape selective constraint index values. 
TABLE I 
__________________________________________________________________________ 
Example 1 2 3 4 5 
__________________________________________________________________________ 
Zeolite ZSM-5 
ZSM-5 
ZSM-5 
ZSM-5 
ZSM-11 
Si/Al.sub.2 600 2860 2500 .about.50,000 
1056 
% Al (orig.) 
0.15% 
0.03% 
-- &lt;0.1% 
&lt;0.1% 
% Al (after treatment) 
2.55% 
1.63% 
-- 1.55% 
1.93% 
Alpha (orig. in H-form) 
17 (est.) 
3 (est.) 
4 (est.) 
0.004 
10 (est.) 
Alpha (after treatment) 
102 75 &gt;100 70 101 
Increase in Alpha 
85 72 &gt;96 70 91 
Constraint Index 
-- -- -- 4.1 4.8 
(after treatment) 
__________________________________________________________________________ 
EXAMPLE 6 
A sample of the activity enhanced zeolite product from Example 2 was 
contacted with a feedstock comprised of 50% aqueous methanol at about 
400.degree. C. and atmospheric pressure. Product effluent was analyzed and 
50% methanol conversion to olefins with 3.4% C.sub.2.sup..dbd. selectivity 
and 37.1% C.sub.3.sup..dbd. selectivity confirmed. 
EXAMPLE 7 
A sample of the activity enhanced zeolite product of Example 3 was 
contacted with a feedstock comprised of 50% aqueous methanol at about 
400.degree. C. and atmospheric pressure. Product effluent analysis 
confirmed 47% methanol conversion to olefins with 36.9% C.sub.2.sup..dbd. 
selectivity and about 25% C.sub.3.sup..dbd. selectivity. 
EXAMPLE 8 
A sample of the activity enhanced zeolite product from Example 3 was 
steamed at 500.degree. C. until its alpha activity was about 5. This 
steamed zeolite was then contacted with 50% aqueous methanol feedstock at 
about 400.degree. C. and atmospheric pressure. Product effluent analysis 
confirmed 78% methanol conversion to olefins with 33.6% C.sub.2.sup..dbd. 
selectivity and about 25% C.sub.3.sup..dbd. selectivity. 
EXAMPLE 9 
A sample of the activity enhanced zeolite product from Example 4 was 
contacted with a feedstock comprised of hexene-1 and 6-methylheptene-1 at 
.degree.C. and atmospheric pressure check competitive relative 
isomerization activity. Selectivity of n/iso isomerization was determined 
to be 2.3. 
As is well known in the art, the alpha activity gives an approximate 
indication of the catalytic cracking activity of the catalyst compared to 
a standard catalyst and it gives the relative rate constant (rate of 
normal hexane conversion per volume of oxide composition per unit time). 
It is based on the activity of the highly active silica alumina cracking 
catalyst taken as an alpha of 1. This test is described in U.S. Pat. No. 
3,354,078 and in The Journal of Catalysis, Vol. 4, pp. 522-529, August, 
1965, each incorporated herein by reference as to that description. 
The constraint index is a measure of the selectivity of a particular 
catalyst and it involves conversion of normal hexane and 3-methylpentane. 
This test is described in many issued U.S. patents, including U.S. Pat. 
No. 4,231,899, incorporated herein by reference as to that description.