CA1096845A - Crystalline zeolite hp - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A novel crystalline zeolite composition is prepared by conducting the hydrothermal cystallization and, preferably, an aging step, at high pressure, i.e.
pressures in excess of 40,000 psig (about 276 MPa (megaPascals)). The crystalline zeolite, designated as zeolite HP, has a structure similar to that of zeolite X but has a higher aluminum content then zeolite X
and a lattice constant of above about 25.02 A.

Description

1~ 45 BACKGROUND OF THE INVENTION
. _ _ _ _ This invention relates to crystalline aluminosilicates. In particular, it relates to a novel crystalline aluminosilicate and its preparation.
Synthetic crystalline aluminosilicates constitute well known materials which have heretofore been employed as selective adsorbents, supports and catalysts. In general, such crystalline materials have been grown under designated conditions of temperature and time from alkali oxide, aluminum oxide, silica and water precursors. The simpliest source materials for preparin~ the more common crystalline aluminosilicates i.e., the type A, X and Y zeolites, are sodium aluminate, sodium silicate and for the more siliceous X and Y types, - an additional source of silicate ions. (The terms crystalline aluminosilicates and zeolites are used herein interchangeably and refer to the same crystalline materials.) Most of the synthesis procedures now in use are tailored to the specific zeolites being prepared.
Crystalline zeolites occur in nature and these natuxal materials were utilized in early investigations of their crystalline structure. Barrer, one of the early investigators, carried out the synthesis of numerous crystalline aluminosilicates using hydrothermal techniques which comprised introducing the reactant mixture into an autoclave and maintaining the mixture for extended periods of time at elevated temperatures as high as 400-450 C. Subsequent investigation by others, such, as Milton, accelerated the eforts for the commercial production of synthetic crystalline aluminosilicates.

14~

Type A, Type X and Type Y zeolites axe among the most useful synthetic crystalline aluminosilicates in use today. The Type A zeolite finds use in gas drying and in one of its particularly preferred embodiments, in an industrial process for separating normal paraffins from hydrocarbon mixtures. The catalytic properties of the Type X and Type Y zeolites have resulted in their commercial use in a variety of industries. By compositing the Type X or Type Y zeolite with an amorphous siliceous matrix, a catalyst is produced which has been found par~icularly useful in the fluid catalytic cracking of petroleum hydrocarbons.
The composition of these crystalline zeolites is:

A Nagç ~ (A12~ 96 (Si02) 96] . 216Ha0 861 t 10~) 86 (Si0 ) 106~ .264H 0 Y Na [(AlO ) (SiO ) ].250H 0 ` Breck and Flanigen in their paper "Synthesis and Properties of Union Carbide Zeolites L, X and Y" present a correlation between the lattice constant of zeolite X and zeolite Y and the number of aluminum atoms in the unit cell. (This paper was read at the conference on molecular sieves held at the University of London on April 4-6, 1967 and published at pages 47-60 of "Molecular Sieves" which is a collection of the papers read at this conference and l~g~45 published by the Society of the Chemical Industry, London, S.W. 1 in 1968.) In their paper, these authors describe the unit cell as containing 192 atoms of silicon and aluminum and define the zeolite Y structure as containing less than about 76 aluminum atoms per unit cell and the zeolite X
structure as having from about 17 to 96 aluminum atoms.
Extrapolation of this correlation shows a lattice constant of 25.02 A, for a zeolite having a 1:1 Si/Al ratio, i.e., 96 aluminum atoms.
Dempsey, Kuhl and Olson, J Phys. Chem, 73, 387 (1969) present a correlation somewhat different from that of Breck and Flanigen. Their correlation between aluminum content of the zeolite and lattice constant shows discontinuities in the correlation at specific compositions which they attribute to a high degree of ordering in the lattice at these points. Extrapolation of th~ir data shows a lattice constant of 25.13 A for a 1:1 Si/Al atomic ratio.
In neither article do the authors present examples for aluminum content per unït cell above 87 atoms. In Breck and Flanigen the upper limit of the data shows a lattice constant of 24.95 A. at 86.5 aluminum atoms while Dempsey, Kuhl and Olson show a lattice constant of 24.99 A. for 86.2 aluminum atoms. The differences in la~tice constant are explained by the different methods of measurement employed.
In these articles there is an implied limit of unit cell composition at a 1:1 ratio of Si to Al atoms because of the so-called "Avoidance Rul~'of Lowenstein which say~ that in aluminosilicate-type structures aluminum ions do not occupy adjacent positions in the lattice. This then limits a Si-Al structure to a 1:1 atomic ratio since a lower ratio would require the aluminum ions to occupy adjacent positions.
A number of procedures have been described for producing synthetic zeolites. These processes require the preparation of aqueous mixtures containing oxides of sodium, silicon and aluminum within certain definite mole ratio limitations. Each proce s requires that this aqueous mixture be subjected to certain conditions to effect crystallization of the desired zeolite species. My U.S. 2,847,280 discloses the aging of an aqueous mixture of the oxides having certain definite mole ratios at a temperature not above 100F (37.8C) for at least 8 hours and then hydrotreating the mixture under autogenous pressure at a temperature of 150-325F. (65.6 - 162.8C) to produce zeolite A. U.S. 2,822,243 of Milton discloses another process of producing zeolite A wherein an aqueous mixture of the oxides in specific mole ratios is maintained at 20-1~5C until crystallization occurs. U.S. 2,982,612 of Barrer et al. discloses still another process of producing zeolite A by maintaining a certain aqueous mixture of oxides at 60-100C to effect crystallization Other aqueous oxide mixes produce zeolite X or Y
under proper conditions. U.S. 2,882,244 of Milton teaches that certain aqueous oxide mixes with produce zeolite X by maintaining the mix at 20-120C while the mixtures disclosed in U.S. 2,979,381 o~ Gottstine et al produce the - same zeolite species when aged at ambient temperature for at least two hours and maintained a~ 185-250F (85-121.1 C) l~q~5 for at least 1 1/2 hours. The more siliceous aqueous mixtures of oxides disclosed in U.S. 3,130,007 of Breck yield zeolite Y when the mix is digested at ambient temperature for 24-32 hours and then maintained at 90-105C for 25-65 hours.
The agirg (digesting) and hydrothermal steps employed in the prior art to prepare synthetic zeolite A, X and Y were conducted under atmospheric or autogenous pressure. In no event were pressures in excess of about 35-50 psig (about 0.2-0.3 MPa) considered as being either necessary or useful in preparing these materials.
Neither were the e~fects of high pressures investigated for any ~eneficial results which might be obtained when preparing these crys~alline aluminosilicates.
- New processes for preparing crystalline alumino-silicates including those employing high pressures, might offer significant advantages over processes presently employed, particularly if the crystalline aluminosilicate prepared thereby would have useful propexties not found in crystalline aluminosilicates prepared hereto~ore.
SU~MARY OF THE INVEN~ION
Broadly this invention is directed to novel L crystalline aluminosilicates and their method of pre-paration. More particularly, by employing pressures in excess of 40,000 psig (about 276 MPa) in the hydrothermal step and, in the optional aging step of a crystalline aluminosilicate preparation, a zeolite having a structure similar to a zeolite X but having a higher aluminum contént and axhibiting propexties not found in zeolite X, is obtained~

_5_ According to one aspect of the present invention there is provided a process for preparing zeolite HP which comprises:
a. forming an aqueous mixture of sodium aluminosilicate having a composition sufficient to establish a ratio of silicon atoms to aluminum atoms of between about 0.25 and about 1.0, b. maintaining said aqueous mixture at a pressure above 20,000 psig (ca. 138 MPa) and a temperature of 150-350F (65.6-176.7 C) for at least three hours, and c. recovering zeolite HP as the resulting solid product.
According to another aspect of the present invention there is pro-vided a synthetic crystalline aluminosilicate, ~eolite HP, having a lattice constant above about 25.02 A and an atom ratio of Si to Al in the unit cell below 1Ø
According to a further aspect of the present invention there is provided a hydrocarbon conversion process which comprises contacting a hydro-carbon charge under catalytic cracking conditions with a synthetic crystalline aluminosilicate, zeolite HP, having a lattice constant above about 25.02 A
and an atom ratio of Si to Al in the unit cell below 1Ø

-5a-4~
BRIEF DESCRIPTION OF THE FIGURES
.
The present invention will be readily understood by reference to the accompanying figures in which:
FIGURE 1 presents the phase diagram of the zeolite species in the Na2O-SiO2-Al2O3 system when the crystallization conditions are 200F (93.3C) and 50,000 psig (ca. 345 MPa).
FIGURE 2 presents the phase diagram of Breck and Flanigen for the zeolite species in the Na2O-SiO2-A12O3 system when the ~rystallization conditions are 200F (93.3C.) and atmospheric or autogenous pressure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
.
Broadly, I have found that the use of high pressure e.g. in excess of 20,000 psig during the synthesis of zeolite crystalline aluminosilicates produces a zeolite having a structure similar to that of zeolite X but containing more aluminum atoms, having a higher lattice constant than zeolite X
and exhibiting properties not found in zeolite X. More particularly, I have found that an aqueous mixture of oxides, which would under techniques employed by the prior art, produce a zeolite A, will, by the utilization of pressures in excess of 40,000 psig (about 276 MPa) during the hydrothermal portion and the optional aging portion of the synthesis produce a zeolite which may generally be termed an aluminum-rich zeolite X. To distinguish this material from zeolite X prepared heretofore, I have designated this material zeolite HP.

Thus, my invention is directed not only to the process of preparing this zeolite but also to the zeolite itself. Zeolite HP is distinguishable from both zeolite X and zeolite Y, to which it is most closely related in the zeolite family, by having a unit cell which contains more aluminum atoms than possible heretofore and having a lattice constant larger than that reported for zeolite X.
Not only does this high aluminum zeolite X differ from other zeolites in its increased ease of ion exchange and depth of exchange but it exhibits novel catalytic and absorptive properties not exhibited heretofore by the prior art zeolites.
Initially, my invention is directed to a process for preparing zeolite ~P which comprises:
a. forming an aqueous mixture of sodium aluminosilicate ha~ing a composition sufficient to establish ratio of silicon atoms toaluminum atoms of between about ~.25 and about 1.0, b. main~aining said aqueous mixture at a pressure above 40,000 psig (ca. 276 MPa) and a temperature of 150-350 F. (65.6-176.7C) for at least three hours, and c. recovering zeolite HP as the resulting solid produc~.
Optionally, and preferably, I find that the quality of the zeolite produced by my process is substantially improved if the aqueous mixture of step (a) is aged at high pressure and about ambient temperatures prior to the hydrothermal crystallization of step (b).
The aging step comprises:

l~Q~4S

aging said aqueous mixture for at least 8 hours at a pressure above 40,000 psig (ca. 276 MPa) and a temperature not above about 100F (37. 8C. ) .
In addition, my invention is directed to the zeolite produced by the processes described above.
Further, my invention is directed to a synthetic zeolitic crystalline aluminosilicate having a lattice constant above about 25.02 A and a ratio of silicon atoms to aluminum atoms in the unit cell of below 1Ø
In preparing zeolite HP an aqueous solution of oxides serves as the starting material. This mixture is an aqueous æolution of the oxides, Na20, A1203 and Si02, or materials whose chemical compositions can be completely represented as mixtures of these oxldes, in specified ranges o~ their mole ratios to produce a mixture wherein the atomic ratio of silicon to aluminumis between about 0.2`5 and about 1.0 This mixture may also be described as one which when subjected to the zeolitic synthesis preparation techniques of the prior art, including for example, atmospheric or autogenous pressure, would produce zeolite A.
In preparing the aqueous mixture of sodium aluminosilicate for use in my process, any prior art . method and formu~ation used to prepare a zeolite A
synthesis mix may be employed provided that the synthesis mixture has a ratio of siIicon atoms to aluminumatoms of 0.25to 1Ø. One aqueous mixtur~ which I ha~e found to be particularly useful is disclosed in my U.S.

2,847,280 and is formulated by reacting an aqueous solution of sodium silicate with C02, S02, H2S, the sodium hydrogen salts of their corresponding acids, (i.e., sodium bicarbonate, sodium bisulfite and sodium hydrosulfide),or mixtures thereof, to form hydrous silica and a by-product sodium salt and then adding sodium aluminate to the mixture in an amount sufficient to establish silicon to aluminum atomic ratio of between about 0.25 and about 1Ø These reactants may be mixed under room temperature conditions and stirred until a thick creamy reaction mixture is formed.
In another embodiment, an aqueous solution of sodium aluminate and sodium hydroxide is combined with an aqueous solution of sodium silicate to produce a mixture in conformity with the atomic ratio range set forth above.
~his solution is the preferred mixture disclosed in Milton's U.S. patent 2,882,243 for preparing a zeolite A.
In still another embodiment, a synthesis mixture of sodium aluminosilicate which I find particularly useful in preparing zeolite HP is formulated by mixing together rapidly an aqueous solution of sodium silicate and an aqueous solution of sodium aluminate. Hydrochloric acid is then added with rapid mixing to produce a uniform gel.
Although zeolite HP is produced by utilizing a high pressure hydrothermal treatment o the synthesis mix, as explained above, a purer product is obtained if an aging treatment, also conducted at high pressure, is performed prior to the hydrothermal crystallization step. A method of preparing zeolite HP which includes both high pressure aging and high pressure hydrothermal treatment is there~ore a particularly preferred embodiment o my invention.

Following the preparation of the aqueous mixture of oxides, the mixture is, optionally, subjected to aging under high pressure and then hydrothermal treatment under high pressure in order to produce zeolite HP. The pressures that I find necessary are substantially higher than those employed heretofore in the synthesis of zeolitic crystalline aluminosilicates. I have found that at pressures of 20,000-40,000 psig (about 138 - about 276 MPa), increasing amounts of zeolite HP are observed in the crystalline product which is a mixture of zeolite A and zeolite HP. I find that pressures in excess of 40,000 psig (about 276 MPa) produce sufficient quantities of zeolite HP in the desired quality.
Although pressures far in excess of 40,000 psig (about 276 MPa? may be used to produce zeolite ~P, those skilled in the art will appreciate that preparation costs will increase si~nificantly when excessively high pressures are employed.
Thus zeolite HP of good quality may be obtained at preparation pressures as high as about 80,000 psig (ca. 552 MPa) but economic considerations hardly justify use of such a preparation pressure. I have found that a pressure of about 50,000 psig ~ca. 345 MPa) is particularly useful.
The high operating pressures described above for use in the zeolite synthesis must be maintained during the hydrothermal step of the preparation and during the optional aging step preceding the hydrothermal step.
Although it is, for operating reasons, usually more convenient to use the same pressure in bo~h steps, this is not critical and the pressures may be different in the aging and hydrothermal treatments provided the pressure in both steps is above 40,000 psig lca. 276 MPa). Time and temperature are the other operating variables which must be controlled during the zeolite synthesis. Thus, I
have found that the high pressure aging should be conducted at about room temperature from 8 to 170 hours, and preferably from 24 to 72 hours at temperatures not substantially above about 100F, but preferably at about room temperature. The high pressure hydrothermal treat-ment is conducted by maintaining the mixture at a temperature of about 150-350F (65.6 - 162.8C) ~or at least three hours, preferably for 4-24 hours.
The synthetic crystalline aluminosilicate obtained in my high pressure synthesis process has a structure similar to that of zeolite X but possesses many distinguish-ing characteristics from this commercially available species of zeolite. The lattice constant for zeolite HP is significantly higher than that for zeolite X. I have found that lattice constants of above about 25.02 A. are obtained for the zeolites produced in my high pressure synthesis when the atomic ratio of silicon to aluminum in the synthesis mix is b~tween about 0.25 and about 1Ø In fact, the range of la~tice constant for zeolite HP appears to be between about 25.02 and about 25.10.
Chemical analysis and ion exchange data of zeolite HP indicate a lower than 1:1 ratio of silicon to aluminum. Because of the "Avoidance Rule", it is unlikely that alwminum ions would occupy adjacent positions in the lattice as required for such a composition. It is possible that the excess aluminum, as alumina, is ~ 45 occluded in ~he large cages of zeolite HP where it displays ion exchange capability. However, there is no visible evidence of such occlusion in the X-ray studies of this zeolite. The possibility must be considered, therefore, that exceptions to the "Avoidance Rule" may occur at the synthesis conditions employed in synthesising zeolite HP. If the lattice constants do repxesent aluminum contents below the l:l relationship predicted by the "Avoidance Rule" the fact that a limit is approached at about 25.10 A would indicate that the exception could occur only at favored sites in the lattice.
Zeolite HP has a variety o uses. As obtained in its synthesis, zeolite HP is in its sodium form. This material finds utility after being ion exchanged with various cations such as calcium, potassium and some of the rare earths. Zeolite HP differs from zeolite X in increased ease of ion exchange and depth of exchange.
Thus, not only is it easier to replace sodi~m in zeolite HP by utilizing fewer number of exchanges but the amount of residual sodium remaining after the exchange is substantially less than that obtained with zeolite X.
Further, subsequent absorption-desorption steps with zeolite HP show peaks which are much sharper and with less tailing than is obtained with zeolite X. This very high degree of ion exchange permits very high loading of rare earth cations i~to the zeolite HP structure.
Thus, when utilized as a cracking catalyst, high equilibrium activities are readily achieved. When zeolite HP, in its rare earth form, is cvmposited with a siliceous matrix, an improved catalytic cracking catalyst having initial high activity is produced. In its lanthenum exchanged form, zeolite HP may be employed to crack hydrocarbons, such as gas oil, utilizing conventional catalytic cracking conditions.
The following examples serve to illustrate my invention:

EXAMPLE I
100 grams of PQ 'N' grade sodium silicate (containing 36.5 wt.% Na2Si409) were diluted with 120 cc of distilled water to produce a 30:1 ratio of water to Si02. Carbon dioxide, in the form of dry ice, was then added in small quantities and replenished, at such a rate that no large excess was ever present, until a gel formed, at which point the remaining bits of dry ice were removed. Excess CO2 Was avoided since it could convert the sodium present to sodium bicarbonate rather than the desired sodium carbonate. The bicarbonate wQuld neutralize a portion of the sodium being added in the next step as sodium aluminate and would interfere with subsequent crystallization. 55 grams of commercial sodium aluminate, containing 95 wt.~ 2 NaA102 .3H20, was dissolved in water to produce about a 30:1 mole ratio of water to salt and in an amount sufficient to produce about a 1:1 ratio of silicon to aluminum atoms when added to the gelled mixture. The aqueous solution of sodium aluminate was added to the gel with rapid mixing to produce a smooth creamy mixture after about 10 minutes of stirring. The mixture approximates the mixtures disclosed in my U.S. 2,847,280 which upon subsequent aging at room temperature and hydrothermal treatment at autogenous pressures and elevated temperatures produced zeolite A.
To evaluate the effect of high pressure on zeolite crystal formation the creamy mixture was divided into five portions. One portion served as a control and was subj ected to aging at atmospheric pressure and hydrothermal treatment at 225F (107.2C) and autogenous pressure. The remaining four portions were subjected to various combinations of aging at atmospheric or elevated pressure and hydrothermal treatment at autogenous pressure or elevated pressure.
In all instances the elevated pressure was 50,000 psig B (about 345 MPa). The high pressure studies were run in a reac~ion vessel constructed of Inconel having a 347 stainless steel liner and a working cavity of approximate-ly 1 3/4 inch ID x 26 inches~ Synthesis mixes in 347 stainless steel vessels were placed in the working cavity and subjected to elevated pressures and temperatures.
Mixes subjected to elevated temperatures and autogenous pressures were placed in screw capped 316 stainless steel vessels having a 200 cc capacity. The screw capped vessels were then placed in circulating air ovens under thermostatic control.
The results of these tests are set forth in Ta~le I below:

~ 7~de~a~ 15-cn H
W ul ~C X
D
~4 H I ~ QJ ,~ QJ
~Z
E~, O
u E~ .
H
W
E~ ~ o el~ o ~r o Z U~ ~ 0~ o~ o æ- ~ u~ ~ O O O o o .
H;~j h ~Q ~ O S~ O n~ :~ O C) ~:~3 _ _ u~
,_ ~ _ C~~ P~ ^ ~ ~ . r~
~: ~ ~ U Ut o o . In r~ o .
~ ~~0 0 ~ 0~ 0~ f`10 0 O ~ ~ -- N ~ a~ ~J ~ ~ _I
~: ~
H ~ a~
W E~~
. m o~ P: E~ s E~
U~
e o ~ o n ~ o o . ~ tn ~ o o o . o .
bq ;E; ~ ~ o c~

V . . ~ ~ ~ ~ ~
Q ~ - 1 1 O . ~ . O
1~~ H~ O O ~ O ~ O
I¢ k ~ Z
C.> ~
i i I ~ I o o O
E~
. . .
~q ~ ~
~, S ~; ~ ~ ~ er U~ O
Z;

,~.
--L~ --~$~4S

An additional run, Run 6, was made to determine the stability of Type 4A zeolite. A quantity of commercial Type 4A manufactured by the Linde Company together with some water was charged to the reaction vessel which was then pressure~ to 50,000 psig (ca 345 MPa) and heated to 200F (93.3C) for 24 hours. The type 4A
sieves were recovered unchanged.
In each of the five runs a crystalline zeolite product was obtained. Run 1 approximates the procedure disclosed in my U.S. patent 2,847,280. As expected, when the aging and hydrothermal treatments were conducted under the moderate conditions of the prior art, zeolite A was prepared. Since the aging portion of the procedure is believed to result in nuc~eation of the favorite species for the particular composition of a synthesis mix, it was not surprising that the exceedingly high pressures utilized during the hydrothermal trea~ment of Run 2 did not produce other than zeolite A. Run 3, on the other hand, employed high pressures of 50,000 p9iy (ca. 345 MPa) in both the aging and the hydrothermal treatment and produced a zeolite type which was not expected - a zeolite similar to zeolite X but having an unusually high aluminum content. Run 4 might have dem~nstrated that the nucleation under high pressure would produce a Type X
zeolite even if the hydrothermal treatment was conducted under moderate conditions. If nucleation did occur under high pressure it was not stable once the influence of pressure was removed since a Type A zeolite was produced in Run 4. Run 5 was conducted with no aging but a hydro-thermal treatment at high pressure. Although a high 6~45 aluminum content Type X zeolite was produced in Run 5 it was of a visibly poorer quality than that which was obtained in Run 3.
The material from Run 3 was subjected to further examination under X-ray diffraction. Calculations using this X-ray data showed the x type material from Run 3 had a lattice constant, aO, of 25.04 ~ 0.01 A. This is very close to the predicted value of 25.02 A by Breck &
Flanigen for a Type X zeolite with a 1:1 Si to Al ratio.
Chemical analysis of the Run 3 product gave a ratio of ~i to Al of 1.16:1; however, this.analysis did not distinguish between zeolite and any amorphous material - which may have been present. The synthesis mix used in these runs had a Si to A1 ratio of 0.96:1.
The results of Run 3 were confirmed by repeating this run with identical results being obtained in terms of the zeolite type. The lattice constant for the crystalline zeolites obtained from these runs, Runs 7 and 8, was: ~
Run 7 25.06 ~ 0.01 Run 8 25.04 + 0.01 EXAMPLE II
200 grams PQN grade sodium silicate (365 wt.%
B NaSi409) was d'luted to 400 cc with distilled water. 282 grams of Nalco #2 stabilized sodium aluminate (Na20/A12Q3 =
1.45/1) was diluted to 400 cc with distilled water. The two ~olutions were mixed rapidly to obtain a uniform consi~tency. Then 42 cc of commercial concentrated hydrochloric acid (12 N) diluted to 100 cc were added e ~1 al^k - 1 8-and the mixture blended until uniform. The gel had a Si/Al atom ratio of 0.79. The gel was char~ed to the high pressure vessel, aged for 20 hours at room temperature under 50,000 psig (ca. 345 MPa) hydrostatic pressure, then heated to 200F (93.3C) for 6 hours. A
zeolite product was collected by filtration and washed with one liter of distilled water. The product yield was 134 grams. X-ray diffraction measurements showed that th~ zeolite had a lattice constant of 25.07 A.
EXAMæLE III
Comparisons of the high pressure zeolite of Run 3 with Type X and Type Y zeolites were made.
Structure determinations of the zeolites were based on X-ray powder patterns. These tests were used both for identification and determination of lattice ' constants.
The da~a published by Breck and Flanigen show a correlation between lattice constant and the number of aluminum atoms in the unit cell of th~ Type X and Y class of zeolites in the hydrated form.
Lattice constant determinations are carried out by measuxing seIected lines in the back re1ection regeneration of the X-ray pattern. Normally the lattice constant given is an average value ~or the aO ~rom the lines measured. X-ray measurements were made on the zeolite from Run 3 and commercially available Type X
-, zeolite. The results are presented in Table II below.
' The first set of data was obtained from the same Miller indices while the second set of data utilized different line identifications.
.

~ s TABLE II
Lattice Constant, a, Data Based On X-Ray Powder Patterns (a) Based on same lines Back Reflection line indent Run 3 Zeolite Type X Zeolite Miller Indices d valve a d valve a ~ _ o o 25, 5, 1 0.9826 25.97 0.9795 24.99 24, 6, 2 1.0095 25.06 1.0267 24.9g 24, 2, 2 1.0367 25.06 1.0339 24.99 (b) Ba~ed on different lines Miller Indices d valve aO Miller Indices d valve aO
_ .
26, 6, ~ 0.g293 ~5.~7 26, 8, 4 0.9088 24.99 26, 4, 2 0.9505 25.07 26, 4, ~ 0.9395 25.0 The zeolite of Run 3 obtained under high pressure and from an aluminum-rich synthesis mixture exhibits a lattice constant as high as Z5.07. This represents an aluminum richness in the zeolite of nearly 10% if the lattice constant correlations of Breck and Flanigen are accepted. Such a composi~ion is supported by chemical analysis of the:Run 3:zeolite HP zeolite whose typical analysis is as follows:
Si/~1 ratio, calculated from X-ray 92/104 Si/Al ratio, chemical analysis 92/104 Chemical analysis also showed the following oxide composition for the sodium form of the Run 3 zeolite HP. Mole %
Na20 26~4 A123 26.0 Si02 ~7.6 ~S~45 EXAMP~E IV
To further investigate the effect of pressure during the aging and hydrothermal synthesis s~eps of crystalline aluminosilicate foxmation, a series of runs was made wherein the pressure was studied over a range of 15,000-50,C00 psig (about 103 to 345 MPa). Two synthesis mix compositions were prepared as in Example I.
Synthesis mixture A had a Si/Al atom ratio of 0.98/l.
Synthesis mixture B had a Si/Al of 0.87/l. In each run the same high pressure was maintained during the aging and the hydrothexmal steps and each synthesis mixture was investigated during each run. Further, a control was run simultaneously with each high pressure study. Thus, each run consisted of four parts. A high pressure synthesis of mixture A plus a control employing mixture A and a high pressure run with mixture B plus a control employing mixture B. Four pressure levels were investigated - 15,000, 30,000, 40,000 and 50,000 psig (ca. 103, 207, 276 and 345 MPa) with repeat runs for the 40,000 and 50,000 psig (ca. 276 2Q and 345 MPa) tests. The product from each run was analyzed by X-ray techniques to identify the type of zeolite obtained. The results of runs 9 to 14 are presented in TableIII below:

l~
X N ¦ 3 N N

~ O ~ ~
C N ~r H ~~1 U~

~1 s ~ xO = mo W 1l0 _~ _ _ ~ ~ ,_ O~ ~ ~ ~ . r~ ~ .
_r~ o ~70 ~ o ~ ~ o r~)o ~a o~ ~
Z ~ C~ Ln 0 11~ 111 0 U~ O U~ O U7 H ¦~: sl O ~ O N O N O t~l O N O ~
H ~ .
~1 ~ ~:: _l o E~ ~0 C~ ~
Ul ~ C) ~ t) C) U
P. ~ ~ o ~o o O o .~ o $ a~ co o ,~ o o ~ o ~ o ~ o ,".

~ .
~ "~ m - l N N ~ N ~ O O

,a)l,Ol u o u o o u - -cl ~ a c -~ ~ N .

~22--The Runs conducted at lS,000 and 30,000 psig did not result in significant quantities of a Type X
zeolite being produced. Although Runs 11 and 13, at 40,000 psig, did result in appreciable amounts of X
Type zeolites being formed, Type A zeolite was also formed as well as some HP type zeolite. Runs 12 and 14 at 50,000 psig pxoduced the alumi~um-rich zeolite HP with no Type A zeolite being present. The lattice constant for the zeolite obtained with Mixture A in Runs 12 and 14 was the same as that obtained in Run 3 where the synthesis mixture had a ratio of 0.94/1. The higher aluminum content of synthesis mixture B gave an increase in lattice constant in Runs 12 and 14.
EXAMPLE V
A number of runs were made to study the effect of the silicon to aluminum ratio. The atom ratio was varied from 0.32/1 to 1.14/1. In Runs 23 and 24 the desired ratio was obtained by additions of sodium ortho-silicate. In each run the aging was conducted at 50,000 psig (ca. 345 MPa) and room temperature for 20 hours while the hydrothermal step was conducted at 50,000 psig (ca. 345 MPa) at 200F (93.3C) for six hours. A
control was run on each synthesis mixture wherein the aging was conducted at atmospheric pressure and the hydrothermal synthesis at autogenous pressures and 225F (107.2C). The product obtained from each high pressure run and control was identified for zeolite type by X-ray. The results are presented in Table IV
below:

-~3--x o o ~ o - ~ o o o o Ou ,o a) +l +l +J + t ~ - ~ ~ er t~ ~D er ~ ~ E~ o o o o o ~
-~ ~ ~ ~ ~ ~ ~

H ~ O O O O O
~ U~
.,; ~ ~ ' ~ Z lC ~ S~ ~ ~
3t ~
m~:c , ~_ o ~`
o o o ~7 ~ -- ~ p~
rd ~ S t) rl ~lo ~ ~: ~
~o ~ . ~ a~ ~ o~ co c~ QO a~ a o u~ o ç~~ o o o o o~
o l ~
o~
u~ lQ
o ~
. h r~ 1 h S-l O h O h O h O
~ P~ U P- U P~ ~ P. U

.,1 P~

U h Z ¦
E~ C~ O;

o o g~ o ~ _, -~ o 0 ~ +'x

3 ~

~ o ~ ~ g n ~ ~ m ~ ~ X ~co ~ ~ ~ ~
~ .
o C~

~ .
R
E~ :
o ~1 o o o U~

Oh _I h ~1~ ~ 1 h ~1 ~--I
0 ~ 0~ 0~ 0 ~ 0 ~ 0 s~~ ~ ~0 ~0 ~ ~ 0 ~
~ah O h Oh O~ O ~ O ~ O
i h I

-2 ~5-l~ S

Zeolite pxoducts were obtained in all cases but in some runs the yields were very poor. There was no significant increase in the lattice constant for the zeolites where the silicon to aluminum mole ratio was below 0.87 to 1. ~owever, there wa~ a consictent change in lattice conStant below this ratio extending i~to the silicon rich mixes which supports the conclusion of aluminum richness in the zeolites ~rom the high aluminum mixes:
EXAMPLE VI
A sample of the high aluminum zeolite (zeolite HP) prepared by the process of this invention and having a lattice constant of 25.06 ~ 0.01 (a portion of the material prepared in Run No. 7) was subjected to absorption tests together with a standard sample of zeolite X ob$ained from the Linde Company. Adsorptions of these two zeolite~
were determined and compared using a dual column i chromatograph. Slurries of the two zeolites were adsorbed B on Chromasorb P to give a 1:3 ratio of zeolite to packing in the two columns. A flow of helium was passed through each column while it was heated to an elevated temperature.
Then a quantity of an adsorbable material was introduced into the helium a~d the adsorption characteristics of each of the zeolites studied. The results obtained are presented in Table IV below.
The general adsorption characteristics of the zeolite HP and th~ zeolite X appear to be about the same with the major difference lying in the ease of desorption.

ac~e /~ k The zeolite HP desorbed more ~uickly with the d sorption peaks visibly demonstrating less tailing, i.e., a cleaner desorption. The exclusion by both sieves of perfluoro tributyl amine indicates that the pore openings are larger than 10 A., since this material is a standard one for measuring maximum pore openings of this size.

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O O-rl ~ 14 ~aE~ ~r EXAMPLE VII
The ion exchange characteristics of Zeolite HP
were studied and compared with the ion exchange properties of a standard zeolite X using the same concentration of exchange solutions and the same number of exchanges. The properties of the two zeolites were as follows:

TABLE VI
ZEO~ITE PR PERTIES

Zeoli-te HP Zeolite X
~ Lattice Constant, aO 25.06 ~ O.OlA 24.95 + 0.04 Si/AI Ratio, X ray 0.92/1 1.09/1 Si/~l Ratio, Chem 0.96/1 1.12/1 Each zeolite was exchanged using calcium potassium and lanthanum salts. Each was compared for degree of exchange and correspondence of the X ray patterns of the exchanged materials to X ray pattern standards.
The calcium exchange utilized calcium formate as the exchange salt. Twenty five grams of the air equilibrated zeolites were treated with 200 ml of a 1.0 normal solution of the salt for 30 minutes at 160 F for each exchange. A total of five exchanges was carried out.
; The zeolites were washed with 500 ml of distilled water between exchanges and with 1000 ml after the final exchange. Finally the samples were washed with 100 ml of acetone and air dried.

s X-ray patterns of the products corresponded with that of a known Ca X zeolite except for small line shifts. Chemical analyses revealed that the zeolite HP
was exchanged to greater extent than the z~olite X. These data are:

96Na20 9~CaO %SiO2 96Al203 Si /Al Ratio Zeolite HP 0.1 18.5 41.4 37.6 0.93 Zeolite X 1.2 15.5 46.2 32.4 1.20 A second experiment using only three exchanges redused the sodium (as sodium oxide) in the zeolite HP
to 0.9 weight per cent, a degree of exchange superior to the zeolite X under the first set of exchange conditions.
The potassium exchange was conducted in a similar manner using the chloride as the exchange salt.
The results of these exchanges are as follows:
Zeolite HP %Na20 ~K20 Si/Al Ratio Zeolite HP 1.03 25.7 0.96 Zeolite X 1.3 21.6 1.15 Again the zeolite HP shows a higher degree of 2Q exchange for equivalent treatment.
The lanthanum axchange used the nitrate as the exchange salt and followed the exchange procedures recommended in Linde Molecular Sieves Technical Bulletin "Ion Exchange and Metal Loading Procedures". As with the previous two experiments there was a significant difference in depth of exchange for a given set of conditions.

~,$~5 Analytical data for the lanthanum exchanged zeolites are:
%Na2 0 %La2 0 3 S i/ Al Ratio Zeolite HP O . 5 32 . 2 0 . 98 Zeolite X 1.1 28.4 1.18 Zeolite HP differs from zeolite X in increased ' ease of ion exchange and depth of exchange.
EXAMPLE VIII
A number of synthesis mixes ha~ing various atom ratios of Al to Si were prepared in a manner similar to that of ExampLe II to develop a phase diagram to show the distribution of zeolitic species in the Na20-SiO2-Al203 system whexe the hydrothermal treatment to effect crystallization was conducted at 50,000 psig (ca. 345 MPa) and 200F ~93.3C). The resultant species included conventional X, zeolite HP as well as other known species obtained in prior art synthesis processes. The phase diagram obtained is presented in Figure l. The data points . are indicated by circles on this tr~ang~lar plot.
2Q. Lattice constant measurements for some of the zeolites were obtained and are noted in Figure l adjacent to the data points.
Figure 1 bears a stri~ing resemblance to the '. zeolite phase diagram presented in Figure 2 which shows the phase diagram for zeolites obtained when the crystallization is performed at atmospheric or autogenous pressure and 200F ~93.3 C). The most significant diff~rence is that there is no zeolite A species in the phase diagram of Figuxe 1 where the high pressure crystallization of my process is employed. It appears that the area _31_ s occupied by zeolite A in Figure 2, appears as zeolite HP in Figure 1. The line between zeolite X and zeolite HP Figure 1 is dotted since its exact location has not been determined. Thus the data point evidencing a ` lattice constant of 24.96 is identified as zeolite X
indicating that the transaction line may well be located below this point.

,i~

_32_

Claims (17)

THE EMBODIMENTS OF TEE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preparing zeolite HP which comprises:
a. forming an aqueous mixture of sodium aluminosilicate having a composition sufficient to establish a ratio of silicon atoms to aluminum atoms of between about 0.25 and about 1.0, b. maintaining said aqueous mixture at a pressure above 20,000 psig (ca. 138 MPa) and a temperature of 150-350 F (65.6-176.7°C) for at least three hours, and c. recovering zeolite HP as the resulting solid product.

2. A process according to claim 1 wherein the pressure of step (b) is above 40,000 psig (ca. 276 MPa) and below about 80,000 psig (ca. 552 MPa).

3. A process according to claim 1 wherein the pressure of step (b) is about 50,000 psig (ca. 345 MPa).

4. A process according to claim 1 wherein the time of step (b) is 4-24 hours.

5. A process according to claim 1 including the following additional step subsequent to step (a) and prior to step (b):
d. aging said aqueous mixture of step (a) for at least 8 hours at a pressure above 40,000 psig (ca. 276 MPa) and a temperature not above 100 F (37.8 C).

6. A process according to claim 5 wherein the pressure of step (d) is above 40,000 psig (ca. 276 MPa) and below about 80,000 psig (ca. 552 MPa).

7. A process according to claim 5 wherein the pressure of step (d) is about 50,000 psig (ca. 345 MPa).

8. A process according to claim 5 wherein the time of step (d) is 24 to 72 hours.

9. A process according to claim 5 wherein the temperature of step (d) is about room temperature.

10. A synthetic crystalline aluminosilicate, zeolite HP, having a lattice constant above about 25.02 A and an atom ratio of Si to Al in the unit cell below 1Ø

11. A synthetic crystalline aluminosilicate, zeolite HP, having a lattice constant between about 25.02 and 25.10 A.

12. The synthetic crystalline aluminosilicate, zeolite HP, of claim 10 having an atom ratio of Si to Al in the unit cell between about 0.25 and 1Ø

13. The synthetic crystalline aluminosilicate, zeolite HP, having a lattice constant between about 25.02 and 25.10 A° and an atom ratio of Si to Al in the unit cell between about 0.25 and 1Ø

14. A hydrocarbon conversion process which comprises contacting a hydrocarbon charge under catalytic cracking conditions with the composition of claim 10.

15. A hydrocarbon conversion process which comprises contacting a hydrocarbon charge under catalytic cracking conditions with the composition of claim 11.

16. A hydrocarbon conversion process which comprises contacting a hydrocarbon charge under catalytic cracking conditions with the composition of claim 12.

17. A hydrocarbon conversion process which comprises contacting a hydrocarbon charge under catalytic cracking conditions with the composition of claim 13.