US 3729409 A
Description (OCR text may contain errors)
April 24, 1973 NA] YUEN CHEN 3,7295409 HYDROCARBON CONVERS ION Filed Dec. 24, 1970 IGD 500 600 700 800 900 I IOOO T,F
INVENTOR NQI YUEN CHEN United States Patent Offiee 3,729,409 Patented Apr. 24, 1973 3,729,409 HYDROCARBON CONVERSION Nai Yuen Chen, Titusville, N.J., assignor to Mobil Oil Corporation Filed Dec. 24, 1970, Ser. No. 101,231 Int. Cl. 010g 35/ 06 US. Cl. 208-135 12 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The upgrading of reformates to improve the octane number of gasolines, as well as the yield-octane relationship has been the subject of much activity in the petroleum industry over the years. Recently, however, because-of the greater awareness of the problem of environmental control, as well as air pollution, greater impetus has been given to investigations directed towards increasing the octane number of gasoline. Quite obviously, processes which will increase the octane number of gasoline are extremely desirable since they will either eliminate the use of lead or minimize the amount of lead needed to raise the product to still higher octane levels.
SUMMARY OF PRIOR ART It has long been known to upgrade a reformate by a wide variety of techniques including treatment with crystalline aluminosilicate zeolites. The treatment of a reformate with crystalline aluminosilicate zeolites heretofore practiced has included both physical treatments such as selective adsorption, as well as chemical treatments such as selective conversion.
Although the prior art procedures for treatment of a reformate ditfered, nevertheless, they had one common characteristic in that substantially all involved the use of crystalline aluminosilicates having a pore size of about angstrom units. Another way of saying the same thing is to state that substantially all prior art procedures for upgrading reformates with zeolites were concerned with those zeolites which would admit normal paratlins and exclude isoparafiins. This was not too surprising since it was known in the prior art that the undesirable components in a reformate generally speaking, were normal parafiins whereas other components of a reformate, i.c. the aromatics and iso-parafiins, were valuable products. Thus, the prior art directed its activities towards the use of zeolites which would selectively remove the normal parafiins and leave the aromatic and/or iso-parafiins in the reformate.
Thus, U.S. Pats. Nos. 2,851,970 and 2,886,508 are directed towards a reforming process where a naphtha is first reformed and the reformate or a portion thereof contacted with a 5 angstrom unit aluminosilicate in order to selectively sorb out the normal parafiins.
US. Pat. No. 3,114,696 represented a substantial improvement in the problem of upgrading a reformate since it was directed towards the concept of treating a reformate with a crystalline aluminosilicate having a pore size of 5 angstroms under cracking conditions so as to selectively crack out the normal parafiins.
US. Pat. No. 3,395,094 represented a still further advance in the overall problem of upgrading a reformate. This patent was directed towards the concept of hydrocracking the normal parafiins out of a reformate with a crystalline aluminosilicate having a pore size of about 5 angstrom units and having hydrogenation activity limited to the internal pore structure thereof. This patent realized that not only was it necessary to selectively crack out normal paraflins, but also to preserve the aromatic constituents of the feed while this operation was being carried out.
DESCRIPTION OF THE INVENTION It has now been discovered that improved results can be obtained in the catalytic treatment of a reformate or reformer efiluent with respect to both octane number and overall yield if such is converted in the presence of added hydrogen with a novel shape selective crystalline aluminosilicate generally identified as the ZSM5 type.
Before the discovery of the ZSM-S type zeolites all the crystalline aluminosilicates heretofore employed in prior art conversion processes fell into one of two general types. They either had pore sizes of about 5 angstrom units or had pore sizes of from about 6 to about 15 angstrom units. The 5 angstrom unit aluminosilicates were generally stated to be shape selective in that they allowed selective conversion of normal aliphatic compounds from a mixture of the same of iso-aliphatic compounds and cyclic compounds. The second type of aluminosilicate, i.c. those generally stated as having a pore size of 6 to 15 angstrom units will admit both normal and iso-aliphatic compounds. Thus, a very convenient method of identifying a good shape selective catalyst was to show that it would selectively sorb hexane from a mixture of the same with 2-methyl pentane since the former compound was able to enter its internal pore structure whereas the latter iso-compound was unable to do so.
The ZSM-S type zeolites which are used in the novel conversion process of this invention can generally be stated to be intermediate between the two types of aluminosilicates previously described. Thus, the ZSM-S type catalysts used in the novel process of this invention will allow the entry into their internal pore structure of normal aliphatic compounds and slightly branched aliphatic compounds, particularly monomethyl substituted compounds, yet substantially exclude all compounds containing at least a quaternary carbon atom or having a minimum molecular dimension equal to or substantially greater than a quaternary carbon atom. Additionally, some aromatic and naphthenic compounds having side chains similar to the normal aliphatic compounds and slightly branched aliphatic compounds above described can enter the internal pore structure of the instant catalysts. Thus, if one were to measure the selectivity of the ZSM-S type materials employed in the process of this invention by the heretofore mentioned prior art test, i.e. the ability to selectively sorb hexane from a mixture of the same with isohexane, these catalysts would have to be stated as being non-shape selective. It should be immediately apparent, however, that the term selectivity has a far greater significance than merely the ability to preferentially distinguish between normal paraflins and iso-paraffins. Selectivity as to shape is theoretically possible at any shape or size although, quite obviously, such selectivity might not result in an advantageous catalyst for any and all hydrocarbon conversion processes.
While not wishing to be bound by any theory of operation, nevertheless, it appears that the crystalline zeolitic materials of the ZSM type employed in the instant invention cannot simply be characterized by the recitation of a pore size or a range of pore sizes. It would appear that the uniform pore openings of this new type of zeolite are not approximately circular in nature, as is usually the case in the heretofore employed zeolites, but rather, are approximately elliptical in nature. Thus, the pore openings of the instant zeolitic materials have both major and minor axis, and it is for this reason that the unusual and novel molecular sieving effects are achieved. This elliptical shape can be referred to as a keyhole. It would appear that the minor axis of the elliptical pores in the zeolites apparently have an effective size of about 5.5 angstrom units. The major axis appears to be somewhere between 6 and about 9 angstrom units. The unique keyhole molecular sieving action of these materials is presumably due to the presence of these approximately elliptically shaped windows controlling access to the internal crystalline pore structure. In any event, irrespective of a particular molecular dimension or of the pore sizes of the ZSM-S type catalyst the simple fact remains that outstanding results have been obtained when a reformate or reactor effluent is converted over a ZSM-S type catalyst. It is noted that the word converted is being employed rather than stating that the reformate is cracked over a ZSM-5 type catalyst for the very simple reason that the mechanism which is involved, although inclusive of cracking of normal and slightly branched paraflins, is far broader than that specific reaction. In fact, the novel process of this invention involves an entirely different chemistry than the chemistry of the heretofore practiced shape selective cracking over a conventional zeolite having a pore size of about 5 angstrom units, i.e. a process such as that described in aforementioned U.S. Pat. No. 3,395,094. While not wishing to be bound by any theory of operation, nevertheless, it appears that the novel process of this invention involves something more than the mere removal of normal paraffins by the selective cracking thereof to gaseous products. Although the cracking of normal parafiins does, indeed, occur in the novel process of this invention, nevertheless, what also appears to be occurring is a simultaneous alkylation of at least a portion of the aromatic rings of aromatic feed with products of cracking of n and/ or slightly branched paraffins thereby resulting in higher alkylated aromatic rings of products. Thus, by way of considerable oversimplification, the novel process of this invention does not merely remove undesirable materials, but rather, removes the undesirable materials and uses them to form alkyl aromatics both directly and by alkylation of aromatics in the feed, thereby resulting in a higher yield of desirable products. Production of alkylaromatics both directly and by aromatics alkylation is exemplified in Example 1 in which a product containing 63.9 weight percent aromatics was made from a charge containing only 50 weight percent aromatics. The direct ring formation is not due to parafiim dehydrocyclization, but rather, to combination of fragments from paraffin cracking coupled wi h hydrog t a fer re ctions In fact, in one embodiment of this invention which will be referred to later on in this specification, a highly parafiinic C straight run gasoline is deliberately added to the reformate or reformer effluent prior to its being converted over a ZSM-S type catalyst. It has been found that a procedure of this type results in enhanced production of alkylaromatics, both directly and by alkylation of the aromatic components, thereby resulting in a more valuable product. Quite obviously, this procedure dramatically illustrates the difference in chemistry between the novel process ot his invention and the heretofore practiced reformate upgrading processes. As can well be i realized, a highly paraflinic straight run gasoline could never be blended with a reformate if the prior art type reformate upgrading processes were employed since the whole purpose of said prior art processes is to remove n-paraflins; therefore n-paraffins would not be deliberately added. Thus, in summary, it would appear that the fundamental distinction between the novel process of this invention and the heretofore practiced upgrading processes of the prior art resides in the fact that not only are certain undesirable compounds selectively removed, i.e. normal and slightly branched parafiins, but that these paraffins alkylate the aromatic portion of the reformate, thereby resulting in an enhanced yield of more desired products.
A further significant result of this chemistry is that dry gas make at the expense of the more valuable gasoline is very low. Methane formation is especially low; this has the advantage of minimal dilution of the recycle hydrogen and thus of optimum reformer operation.
As has heretofore been pointed out, the novel process of this invention resides in the treatment of a reformate or reformer effluent in the presence of hydrogen over a crystalline aluminosilicate of the ZSM-S type. The reformate or reformer efiluent which is treated in accordance with the novel process of this invention is preferably one which contains substantially only aromatic and paraffinic constituents, although it is possible to tolerate naphthenes and olefins in the feed.
Reformates or reformer effluents which are composed substantially of aromatic and paraffinic constituents can be prepared according to conventional techniques by contacting any suitable material such as a naphtha charge material boiling in the range of about C and preferably from about C up to about 380 F. and higher with hydrogen at least initially in contact with any conventional reforming catalyst. This is a conventional reforming operation and is disclosed in greater detail in U.S. Pat. No. 3,395,094.
Typical reforming operations include the use of platinum type reforming catalysts. They may include, for example, alumina in the eta, chi, or gamma form and mixtures thereof in combination with a noble metal. Platinum type includes, for example, the metal series which includes platinum, palladium, osmium, iridium, ruthenium or rhodium and mixtures thereof deposited on a suitable support. Metals of Group VII-B, including rhenium, may be used in combination with platinum-type metals. Generally, the major portion of the catalyst will be alumina, which may comprise as much as about by weight or more of the catalyst. Other components may be combined with the alumina carrier, such as the oxides of silica, magnesium, zirconium, thorium, vanadium, titanium, boron or mixtures thereof. The platinumalumina combination, either with or without one or more of the above-listed components such as silica, etc., may also be promoted with small amounts of halogen such as chlorine and fluorine, in amounts ranging from about 0.1% up to about 5 by weight. Generally, less than about 3% of halogen is employed with the platinum type catalyst. In a preferred embodiment, the reforming catalyst carrier material is a relatively high surface area material, preferably an eta alumina material of at least about square meters per gram. Preparation of the catalysts may be accomplished by many different procedures described in the prior art. In one procedure an alumina carrier material is impregnated with the acid or salt of one or more of the herein-described platinum type hydrogenating components in amounts that will produce from a fraction of a percent up to about 1% by weight of the metal, but generally not substantially more than about 0.6% by Weight of platinum is employed.
It is to be understood that a naturally occurring or synthetically prepared alumina with or without silica may be employed as a carrier material or support for the platinum type reforming catalyst. Preferably, the platinum-alumina catalyst employed comprises a high surface area material such as an eta base alumina discussed above. Before use, the high surface area platinum catalyst may be reduced in a hydrogen atmosphere and maintained preferably in a relatively dry moisture-free atmosphere before being put on-stream. Desiccated conditions for the catalyst are preferred since it has been found that, at temperatures commonly found in reformers the desired high surface area of the catalyst decreases with increasing moisture content, and this has simultaneous deactivating effect on the catalyst. Accordingly, it is preferred to employ in the platinum reforming step relatively dry reforming conditions. This is particularly true when employing relatively low pressure reforming conditions below about 400 p.s.i.g., and not substantially above about 200 p.s.i. g.
It is to be understood that the term platinum type reforming catalyst designates a catalyst which performs the well-known reforming reactions of a hydroisomerization and aromatization under conditions creating a negligible concentration of olefins in the efiluent product. While the above described catalysts are examples of this class, the platinum type catalyst and term as used in connection with this invention should not be construed to be restricted to a particular chemical composition per se, as regards the platinum type metal nor the base or support material.
For example, it is contemplated using as a platinum type reforming catalyst, compositions which may include a crystalline aluminosilicate base substance having a pore structure sufiiciently large to allow passage therein of substantially all molecules contained in a naphtha charge in association with a dehydrogenative element of the transition metal series, which crystalline aluminosilicate has an acidic catalytic activity that has been adjusted to a relatively low level characterized by an alpha value of less than 1.0 and preferably of about .01 to 0.1. The alpha scale and the method of its measurement has been described in a publication, the Journal of Catalysis, vol. 4, No. 4, August 1965, pages 527-529. In the case of catalysts with associated dehydrogenative metal, the alpha test is carried out after suitable poisoning of the metal activity, as by prior contact with a sufficiently large amount of hydrogen sulfide. In the above example, the prescribed low level of acidic activity may be achieved by providing the catalyst with a controlled and relatively high concentration of alkali metal ions.
In the reforming process, typical reforming operating conditions including temperatures in the range of from about 800 F. to about 1000 F., preferably from about 890 up to about 980 F., liquid hourly space-velocity in the range of from about 0.1 to about 10, preferably from about 0.5 to about 5; a pressure in the range of from about atmospheric up to about 700 p.s.i.g. and higher, preferably from about 100 to about 600 p.s.i.g.; and a hydrogenhydrocarbon ratio in the range of from about 0.5 to about and preferably from about 1 to about 10.
In the process of this invention, the reformate or reformer effiuent is contacted in the presence of hydrogen over a ZSM-5 type catalyst. As will be seen from comparison of Examples 2 and 3, the process chemistry seems the same with or without the presence of hydrogen.
Although there does not appear to be any chemical reason that makes added hydrogen necessary in order to upgrade the reformate in accordance with the process of this invention, nevertheless, from a practical point of view it appears that the production of the reformate via a reforming reaction always results in the production of hydrogen and it would neither be necessary nor desirable to separate out this hydrogen which, in fact, may provide added benefits insofar as the catalyst is concerned, particularly with respect to stability. Practically, it is undesirable to separate out the hydrogen because it would add to processing cost, and because the reduced dilution of hydrogen recycled to the reformer associated with practicing the process of this invention improves the prior reforming operation. It is to be immediately understood, however, that it is not necessary to have a hydrogenadon/dehydrogenation component associated with the ZSM-S type catalyst, although such is a preferred embodiment of this invention. Thus, in its broadest form this invention includes processing of a reformate or reformer effluent in the presence of hydrogen over a ZSM-S type catalyst with or without an added hydrogenation component.
A test method has been devised in order to determine whether or not a zeolite possesses the unique molecular sieving properties necessary to carry out the novel conversion process of this invention. In said test method a candidate zeolite free from any matrix binder is initially converted to the so-called acid or hydrogen form. This procedure involves exhaustive exchange With an ammonium chloride solution in order to replace substantially all metallic cations originally present. It may also involve calcination prior to one or more ammonium exchange steps. The sample is then dried, sized to 20-30 mesh and calcined in air for 16 hours at 550 C. One gram of the so-treated zeolite is then contacted with benzene at a pressure of twelve torr at a temperature of 25 C. for a time period of two hours. Another gram sample is con tacted with mesitylene at a pressure of 0.5 torr at a temperature of 25 C. for a period of six hours. A preferred zeolite is one whose acid form will adsorb at least 3.0 weight percent benzene and less than 1.5 weight percent mesitylene at the above-recited conditions.
Examples of zeolitic materials which are operable in the process of this invention are ZSM5 type which family includes not only ZSM-5 but also ZSM-8 zeolites. ZSM-S type materials are disclosed and claimed in copending application Ser. No. 865,472, filed Oct. 10, 1969, and ZSM8 is disclosed and claimed in copending application Ser. No. 865,418, filed Oct. 10, 1969.
The family of ZSM-5 compositions has the character istic X-ray diffraction pattern set forth in Table 1, hereinbelow. ZSM-S compositions can also be identified, in terms of mole ratios of oxides as follows:
wherein M is a cation, n is the valence of said cation, W is selected from the group consisting of aluminum and gallium, Y is selected from the group consisting of silicon and germanium, and z is from 0 to 40. In a preferred synthesized form, the zeolite has a formula, in terms of mole ratios of oxides, as follows:
and M is selected from the group consisting of a mixture of alkali metal cations, especially sodium, and tetraalkylammonium cations, the alkyl groups of which preferably contain 2-5 carbon atoms.
TABLE 3C0ntinued H01 NaCl CaOlz ReCls AgNO As made 7 In a preferred embodiment of ZSM-5, W is aluminum, Y is silicon and the silica/alumina mole ratio is at least 10 and ranges up to about 60.
Members of the family of ZSM-5 zeolites possess a This mixture is maintained at reaction conditions until the crystals of the zeolite are formed. Thereafter the crystals are separated from the liquid and recovered. Typical reaction conditions consist of a temperature of from about 75 C. to 175 C. for a period of about six hours to 60 days. A more preferred temperature range is from about '90 to 150 C., with the amount of time at a temperature in such range being from about 12 hours to 2 days.
The digestion of the gel particles is carried out until crystals form. The solid product is separated from the reaction medium, as by cooling the whole to room temperature, filtering and water washing.
ZSM- is preferably formed as an aluminosilicate. The composition can be prepared utilizing materials which supply the elements of the appropriate oxide. Such compositions include, for an aluminosilicate, sodium aluminate, alumina, sodium silicate, silica hydrosol, silica gel, silicic acid, sodium hydroxide and tetrapropylammonium hydroxide. It will be understood that each oxide component utilized in the reaction mixture for preparing a member of the ZSM-S family can be supplied by one or more initial reactants and they can be mixed together in any order. For example, sodium oxide can be supplied by an aqueous solution of sodium hydroxide, or by an aqueous solution of sodium silicate; tetrapropylammoni'um cation can be supplied by the bromide salt. The reaction mixture can be prepared either batchwise or continuously. Crystal size and crystallization time of the ZSM-S composition will vary with the nature of the reaction mixture employed. ZSM-8 can also be identified, in terms of mole ratios of oxides, as follows:
0. 95:11.2 M 2 O:Al203:5100 Si022Z 11 0 wherein M is at least one cation, n is the valence thereof and z is from 0 to 40. In a preferred synthesized form, the zeolite has a formula, in terms of mole ratios of Oxides, as follows:
(1910.2 M toAlzomlHo SiOz:Z H O and M is selected from the group consisting of a mixture of alkali metal cations, especially sodium, and tetraethylammonium cations.
ZSM-8 possesses a definite distinguishing crystalline structure having the following X-ray diffraction pattern;
TABLE 4 d, A. 1 I/I a, A.
11. 1 46 4 2. 97 10. O 42 3 2. 94 9. 7 1O 2 2. 86 9. O 6 1 2. 78 7. 42 10 4 2. 73 7.05 7 1 2.68 6. 69 5 3 2. 61 6. 35 12 1 2. 57 6. 01 e 1 2. 55 5. 97 12 1 2. 51 5. 69 9 6 2. 49 5.56 13 1 2. 45 5.36 3 2 2. 47 5.12 4 3 2.39 5. 01 1 1 2. 35 4. 5o 7 1 2. 32 4. 45 3 1 2. 28 4. 35 7 1 2. 23 4. 25 18 1 2. 20 4. O7 20 1 2. 17 4. O0 10 1 2. 12 3.85 100 1 2.11 3. 82 57 1 2. 08 3. 75 1 2. 06 3.71 6 2.01
Zeolite ZSM8 can be suitably prepared by reacting a water solution containing either tetraethylammonium hydroxide or tetraethylammonium bromide together with the elements of sodium oxide, aluminum oxide, and an oxide of silica.
The operable relative proportions of the various ingredients have not been fully determined and it is to be immediately understood that not any and all proportions of reactants will operate to produce the desired zeolite. In fact, completely different zeolites can be prepared utilizing the same starting materials depending upon their relative concentration and reaction conditions as is set forth in U.S. Pat. No. 3,308,069. In general, however, it has been found that when tetraethylammonium hydroxide is employed, ZSM-S can be prepared from said hydroxide, sodium oxide, aluminum oxide, silica and water by reacting said materials in such proportions that the forming solution has a composition in terms of mole ratios of oxides falling within the following range SiO /Al O -from about 10 to about 200 Na o/tetraethylammonium hydroxide-from about 0.05
Tetraethylammonium hydroxide/SiO from about 0.08
H o/tetraethylammonium hydroxidetfrom about to about 200 Thereafter, the crystals are separated from the liquid and recovered. Typical reaction conditions consist of maintaining the foregoing reaction mixture at a temperature of from about C. to 175 C. for a period of time of from about six hours to 60 days. A more preferred temperature range is from about to C. with the amount of time at a temperature in such range being from about 12 hours to 8 days.
The ZSM-S type zeolites used in the instant invention usually 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 including mixtures of the same. Of the replacing cations, particular preference is given to cations of hydro gen, ammonium, rare earth, magnesium, zinc, calcium, nickel, and mixtures thereof.
Typical ion exchange techniques would be to contact the particular zeolite 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 disclosed in a wide variety of patents including U.S. Pats. Nos. 3,140,249; 3,140,251; and 3,140,253.
Following contact with the salt solution of the desired replacing cation, the zeolites may be washed with water and dried at a temperature ranging from 150 F. to about 600 F. and thereafter heated in air or other inert gas at temperatures ranging from about 500 F. to 1500 F. for periods of time ranging from 1 to 48 hours or more.
It is also possible to treat the zeolite with steam at elevated temperatures ranging from 800 F. to 1600 F. and preferably 1000 F. and 1500 R, if such is desired. The treatment may be accomplished in atmospheres consisting partially or entirely of steam.
A similar treatment can be accomplished at lower temperatures and elevated pressures, e.g. 350-700 F. at 10 to about 200 atmospheres.
A preferred embodiment of this invention resides in the use of a porous matrix together with the ZSM- type zeolite previously described. The ZSM-S type zeolite can be combined, dispersed or otherwise intimately admixed with a porous matrix in such proportions that the resulting product contains from 1% to 95% by weight, and preferably from to 70% by weight, of the zeolite in the final composite.
The term porous matrix includes inorganic compositions with which the aluminosilicates can be combined, dispersed or otherwise intimately admixed wherein the matrix may be active or inactive. It is to be understood that the porosity of the compositions employed as a matrix can either be inherent in the particular material or it can be introduced by mechanical or chemical means. Representative matrices which can be employed include metals and alloys thereof, sintered metals and sintered glass, asbestos, silicon carbide aggregates, pumice, firebriok, diatomaceous earths, and inorganic oxides. Inorganic compositions especially those of a siliceous nature are particularly preferred because of their superior poclay, chemically treated clay, silica, silica-alumina, etc., are particularly preferred because of their superior porosity, attrition resistance, and stability.
The compositing of the aluminosilicate with an inorganic oxide can be achieved by several methods wherein the aluminosilicates are reduced to a particle size less than 40 microns, preferably less than 10 microns, and intimately admixed with an inorganic oxide while the latter is in a hydrous state such as in the form of hydrosol, hydrogel, wet gelatinous precipitate, or in a dried state, or a mixture thereof. Thus, finely divided aluminosilicates can be mixed directly with a siliceous gel formed by hydrolyzing a basic solution of alkali metal silicate with an acid such as hydrochloric, sulfuric, acetic, etc. The mixing of the three components can be accomplished in any desired manner, such as in a ball mill or other types of mills. The aluminosilicates also may be dispersed in a hydrosol obtained by reacting an alakli metal silicate with an acid or alkaline coagulant. The hydrosol is then permitted to set in mass to a hydrogel which is thereafter dried and broken into pieces of desired shape or dried by conventional spray drying techniques or dispersed through a nozzle into a bath of oil or other water-immiscible suspending medium to obtain spheroidally shaped bead particles of catalyst such as described in US. Pat. No. 2,384,946. The aluminosilicate siliceous gel thus obtained is washed free of soluble salts and thereafter dried and/ or calcined as desired.
In a like manner, the aluminosilicates may be incorporated with an aluminiferous oxide. Such gels and hydrous oxides are well known in the art and may be prepared, for example, by adding ammonium hydroxide, ammonium carbonate, etc. to a salt of aluminum, such aluminum chloride, aluminum sulfate, aluminum nitrate, etc., in an amount sufiicient to form aluminum hydroxide which, upon drying, is converted to alumina. The aluminosilicate may be incorporated with the aluminiferous oxide while the latter is in the form of hydrosol, hydrogel, or wet gelatinous precipitate or hydrous oxide, or in the dried state.
The catalytically active inorganic oxide matrix may also consist of a plural gel comprising a predominant amount of silica with one or more metals or oxides there of selected from Groups I-B, II, III, IV, V, VI, VII and VIII of the Periodic Table. Particular preference is given to plural gels or silica with metal oxides of Groups ILA,
III and -1Va of the Periodic Table, especially wherein the metal oxide is rare earth oxide, magnesia, alumina, zirconia, titania, beryllia, thoria, or combination thereof. The preparation of plural gels is Well known and generally involves either separate precipitation or coprecipitation techniques, in which a suitable salt of the metal oxide is added to an alkali metal silicate and an acid or base, as required, is added to precipitate the corresponding oxide. The silica content of the siliceous gel matrix contemplated herein is generally within the range of 55 to weight percent with the metal oxide content ranging from 0 to 45 percent.
The inorganic oxide may also consist of raw clay or a clay mineral which has been treated with an acid medium to render it active. The aluminosilicate can be incorporated into the clay simply by blending the two and fashioning the mixture into desired shapes. Suitable clays include attapulgite, kaolin, seipiolite, polygarskite, kaolinite, halloysite, plastic ball clays, bentonite, montmorillonite, illite, chlorite, etc.
Other useful matrices include powders of refractory oxides, such as alumina, alpha alumina, etc., having very low internal pore volume. Preferably, these materials have substantially no inherent catalytic activity of their own.
The catalyst product can be heated in steam or in other atmospheres, e.g. air, near the temperature contemplated for conversion but may be heated to operating temperatures initially during use in the conversion process. Generally, the catalyst is dried between F. and 600 F. and thereafter may be calcined in air, steam, nitrogen, helium, flue gas or other gases not harmful to the catalyst product at temperatures ranging from about 500 F. to 1600" F. for periods of time ranging from 1 to 48 hours or more. It is to be understood that the aluminosilicate can alsobe calcined prior to incorporation into the inorganic oxide gel. It is also to be understood that the aluminosilicate or aluminosilicates need not be ion exchanged prior to incorporation in a matrix but can be so treated during or after incorporation into the matrix.
As has previously been stated, it is also possible to have a hydrogenation/dehydrogenation component present in the catalyst composition.
The amount of the hydrogenation/dehydrogenation component employed is not narrowly critical and can range from about 0.01 to about 30 weight percent based on the entire catalyst. A variety of hydrogenation components may be combined with either the ZSM-S type zeolite and/ or matrix in any feasible manner which affords intimate contact of the components, employing well known techniques such as base exchange, impregnation, coprecipitation, cogellation, mechanical admixture of one component with the other, and the like. The hydrogenation component can include metals, oxides, and sulfides of metals of the Periodic Table which fall in Group VI-B including chromium, molybdenum, tungsten and the like; Group II-B including zinc cadmium; Group VII-B including manganese and rhenium and Group VIII including cobalt, nickel, platinum, palladium, ruthenium, rhodium and the like, and combinations of metals, sulfides and oxides of metals of Groups VI-B and VIII, such as nickel-tungstem-sulfide, cobalt oxide-molybdenum oxide and the like.
The pre-treatment before use varies depending on the hydrogenation component present. For example, with components such as nickel-tungsten and cobalt molybdenum, the catalyst is sulfur activated as by snlfiding. With metals like platinum or palladium, a hydrogenation step is employed. These techniques are well known in the art and are accomplished in a conventional manner.
Within the above description of the ZSM-S type zeolites which can be used alone or physically admixed in a porous matrix, it has been found that certain aluminosilicates provide superior results when employed in the process of this invention.
First of all, it is preferred that there be a limited amount of alkali metal cations associated with the aluminosilicates since the presence of alkali metals tends to suppress or limit catalytic properties, the activity of which as a general rule decreases with increasing content of alkali metal cations. Therefore, it is preferred that the aluminosilicates contain no more than 0.25 equivalent of alkali metal cations per gram atom of aluminum and more preferably no more than 0.15 equivalent per gram atom of aluminum of alkali metal cations.
With regard to the metal cations associated with the ZSM- type aluminosilicate, the general order of preference is first cations of trivalent metals, followed by cations of divalent metals, with the least preferred being cations of monovalent metals. Of the trivalent metal cations, the most preferred are rare earth metal cations, either individually or as a mixture of rare earth metal cations.
However, it is particularly preferred to have at least some protons or proton precursors associated with the aluminosilicate via exchange with ammonium compounds or acids.
Conversion in accordance with the present process is generally carried out at a temperature between 500 F. and about 1000 F. and preferably 550-850 F. The hydrogen pressure in such operation is generally within the range of about 100 and about 3000 p.s.i.g. and preferably about 350 to about 2000 p.s.i.g. The liquid hourly space velocity, i.e. the liquid volume of hydrocarbon per hour per volume of catalyst is about 0.1 and about 250, and preferably between about 1 and 100. In general the molar ratio of hydrogen to hydrocarbon charge employed is between about 1 and about 80, and preferably between about 2 and about 15.
The aforementioned conditions of temperature and pressure for carrying out the novel process of this invention are generally applicable over their entire range when a ZSM-S catalyst is employed which does not possess hydrogenation/ dehydrogenation activity.
When hydrogenation/ dehydrogenation activity is associated with the ZSM-S type catalyst, greater care must be taken in choosing conditions of temperature and presure so that aromatics present in the reformate or reformer eflluent are not hydrogenated.
It has now been found that within the range of process conditions employed for carrying out conversion with the ZSM-S type catalyst, there are certain ranges of temperature and pressure within said broad range wherein it is thermodynamically possible to hydrogenate aromatics and there are ranges of temperature and pressure wherein it is thermodynamically impossible to hydrogenate aromatic compounds. Thus, although the selective hydrocracking of normal paraffins and the hydrogenation of olefins can take place at a fairly wide range of temperatures and pressures, the hydrogenation of aromatic compounds is thermodynamically feasible only within a narrower range of the temperatures and pressures utilized in conversions with the ZSM-S type catalyst having hydrogenation activity.
The selectivity in the hydrogenation/dehydrogenation function is achieved in one of two general procedures. The selective conversion operation is carried out at such conditions of temperature and pressure that prevent substantial hydrogenation of aromatics, in which case a broad range of hydrogenation/dehydrogenation catalyst components can be associated with the ZSM-S type catalysts.
The sole exception to this general principle resides in the fact that certain hydrogenation components cannot be used which cause destructive hydrogenolysis of aro matics and in this connection, the materials which have such exceptionally high activity and fall within Group VIII of the Periodic Table.
The second way in which an effective process can be obtained is to employ those conditions of temperature and pressure wherein it is, in fact, thermodynamically possible to hydrogenate aromatics, but to operate with low levels of hydrogenation components such that insufficient hydrogenation/ dehydrogenation activity is present to catalyze the hydrogenation of aromatics.
Thus, it can be seen that the process of this invention resides in the use of hydrogenation/ dehydrogenation components of any strength short of causing destructive hydrogenolysis of aromatics in those situations wherein temperatures and pressures are employed wherein it is thermodynamically impossible to hydrogenate aromatics and the use of hydrogenation/dehydrogenation components having mild hydrogenation activity when using conditions of temperature and pressure such that it is thermodynamically possible to hydrogenate aromatics.
This will be better understood by reference to the accompanying drawings wherein:
FIG. 1 shows three curves and represents a graph of those operating conditions wherein the selective conversion with the type B catalyst is carried out;
The three curves represent the temperature and pressure required to hydrogenate 10 weight percent of the aromatics in a charge stock at hydrogen to aromatics ratios of 2.5 :1, 10:1, and 40:1, respectively.
To the left of said curves an area designated as A represents those conditions of temperature and pressure wherein it is thermodynamically possible to hydrogenate more than 10 weight percent aromatics; and
To the right of said curves represents an area identilied as B wherein it is thermodynamically impossible to hydrogenate aromatic compounds, i.e., less than 10 weight percent conversion.
Thus, when operating in those sets of conditions defined by area B, any hydrogenation/dehydrogenation component can be employed of any strength so long as destructive hydrogenation of aromatics does not occur. Thus, when operating in area B, metals of Groups IB, II-B, V, VI and VII of the Periodic Table, including the oxides and sulfides thereof, can be employed in any amount and in any concentration since under these conditions all the olefins will be hydrogenated and aromatics will be substantially unaffected. As has been previously set forth, it would not be possible to employ metals of the Group VIII of the Periodic Table since these metals contain too high activity and would cause destructive hydrogenolysis of benzene. It is to be noted, however, that Group VIII metals and compounds thereof can be employed if their activity is lessened or deactivated by pretreatment, coking or addition of a deactivant to the charge to a level such that negligible benzene conversion does occur.
When operations are carried out at conditions of temperature and pressure falling within area A of said graph, then the choice of the hydrogenation/dehydrogenation component becomes more critical. In this type of operation, it is possible to use hydrogenation components falling within Group I-B' and Group II-B of the Periodic Table in any concentration since it has been found that these materials do not possess sufficient hydrogenation/dehydrogenation activity to hydrogenate aromatics at these conditions. If hydrogenation components selected from Groups V, VI and VII of the Periodic Table are to be employed, then these materials must be used at sufliciently low concentration to have negligible aromatic hydrogenation activity. In this connection, it has been found that the amount of these materials should range from about 0.05 to about 4.5 weight percent based on the total weight of hydrogenation component and aluminosilicate. Particularly preferred concentrations are from 2.0 percent to about 3 weight percent of the hydrogenation component.
Quite obviously, metals from Group VIII of the Periodic Table as well as their oxides or sulfides are not suitable for use since the activity of these materials is so high that hydrogenation of aromatics will occur. However, in like manner, as when operating in those conditions defined by A, it is possible to employ these compounds, providing 15 the activity thereof has been sufiiciently reduced so that negligible hydrogenation of aromatic compounds occurs.
In order to determine whether or not the hydrogenation activity of a candidate catalyst is such that negligible hydrogenation of aromatic compounds occurs, i.e. as a result of deliberately decati-vating a Group VIII metal catalyst or using low concentration of Groups V, VI and VII, a convenient test method has been developed so that it can be very quickly and easily determined whether or not a particular catalyst is suitable.
In this test method a candidate catalyst, i.e. a ZSM-S type zeolite having hydrogenation/ dehydrogenation activity, is contacted with a hydrocarbon mixture containing about 50 weight percent benzene, 25 weight percent n-hexane and 25 weight percent isohexane at a presure of 200 p.s.i.g., a temperature of 700 F., a LHSV of 4.0 (with respect to total hydrocarbons) and a hydrogen to benzene mole ratio of 30:1. The contact is carried out for 60 minutes and the reactor effluent is thereafter analyzed periodically, e.g. at 15 minutes and 45 minutes. If less than 10 weight percent of benzene is converted by hydrogenation, the catalyst is suitable as to hydrogenation activity for use in the novel process of this invention.
When operating at those conditions wherein it is thermodynamically impossible to hydrogenate aromatics, i.e. Area A in FIG. 1, a simple test method has also been devised to determine whether or not the activity of the Group VIII metal and compounds thereof have been sufficiently reduced so that destructive hydrogenolysis of aromatics does not occur.
In this test a ZSM-S type zeolite having a Group VIII metal or compound thereof on its external surface is contacted with a mixture of 50 weight percent benzene, 25 weight percent n-hexane and 25 weight percent isohexane in an identical manner as above-described with the exception that the temperature of contact is 900 F. The remaining conditions are the same, i.e. pressure 200 p.s.i.g., LHSV 4.0, hydrogen/benzene ratio 30:1. The reactor effluent is analyzed and if less thanlO Weight percent of benzene is found to have been destroyed, the catalyst is deemed acceptable as to aromatics hydrogenolysis for use in the process of the instant invention.
The novel process of this invention can be carried out in a wide variety of techniques utilizing the process param eters previously set forth. Thus, it is possible to carry out this selective conversion in a separate reactor. In this embodiment a conventional reformer is operated so as to yield a reformate of the type previously set forth and then the reformate or reactor effluent, together with added hydrogen is passed into a separate reactor containing a ZSM-S type catalyst with or without a hydrogenation component in the manner previously set forth. In another embodiment of this invention a separate reactor need not be employed, but rather, the last reactor in a conventional three reactor reforming operation can be filled with a conventional platinum reformin catalyst and with the ZSM-S type catalyst previously set forth so that the hydrocarbon feed first contacts the conventional platinum reforming catalyst and then the ZSM-S type catalyst. Thus, a feed material would undergo conventional reforming in the first two stages of a conventional reactor and then would enter into a third stage wherein conventional reforming would be carried out at the top of the reactor followed by the selective con-version in the bottom of the reactor with the ZSM-5 type catalyst. This embodiment has the advantage of utilizing existing equipment and carrying out the novel process of this invention.
As has heretofore been pointed out, one embodiment of this invention resides in the introduction of a highly paraffinic straight run gasoline into the reformate or re former etfiuent which is being converted with the ZSM-S type catalyst. As has been previously stated, it would appear that the novel process of this invention provides for the alkylation of the aromatic consitituents of the charge thereby resulting in significantly upgraded products having enhanced economic value. The introduction of a highly paraflinic material such as straight run gasoline tend to increase the degree of alkylation attained thereby resulting in the obtainment of valuable products.
Although this invention has been described with respect to improved benefits stemming from increasing the octane number of the reformate as well as increasing the yield octane relationship thereof, nevertheless, there are other advantages of the novel process of this invention over the heretofore practiced prior art techniques. One significant advantage is the fact that in practicing the process of this invention a greater hydrogen purity is obtained than the corresponding procedures of the prior art. Thus, for a given octane improvement in the upgrading of a reformate the novel process of this invention results in a higher degree of hydrogen purity due to the fact that there is an extremely low tendency to produce methane with the ZSM-S type catalyst of this invention. A greater degree of hydrogen purity possesses obvious economic advantages.
The following examples will now illustrate the best mode contemplated for carrying out this invention.
EXAMPLES 1-2 These examples will illustrate the novel chemical reactions which are taking place when ZSM-5 type catalysts are used. In Example 1 n-octane was charged and in Example 2 an equal part by weight mixture of n-octane and benzene was charged. In each case the hydrogen form of ZSM-5 was employed and the following reaction conditions were used:
Pressure: 500 p.s.i.g. Temperature, F.: 525 LHSV: 1
Hydrogen: None The results were as follows:
Overall yields Example 1 Example 2 G./ charge:
Butanes 12. 8 9. 9
Pentanes 16. 4 6. 4
C paraflins- 4. 8 1. 2
C1 paraflins 2. 4 0. 2
Ca paratfins..- 49. 7 13. 5
Benzene 1. 1 33. 3
Alkylbeuzenes (01-13) 4.3 26. 2
Tetralins, lndanes 0. 6 3. 8
Naphthalenes 0. 2 0. 6
Naphthenes. 2. 2 0. 1
Olefins 1. 8 0. 9
Total, g 100. 0 100. 0
Of the 50.3 g. of n-octane disappearing from the charge of n-octane alone (Example 1), 40.6 g. (81%) went to lower carbon number parafiins and 6.2 g. (12%) to aromatics. Smaller amounts went to naphthenes (5%) and olefins (2% In Example 2, the charge had 50 weight percent aromatics whereas the product had 63.9 weight percent aromatics.
EXAMPLES 3-23 The following examples will illustrate the novel process of this invention. In each case the feed was a reformate obtained by contacting a mid-continent type naphtha together with hydrogen over a platinum reforming catalyst at 8001000 F. and a pressure of about 500 p.s.i.g.
The reformate together with hydrogen was then contacted with a nickel-hydrogen exchanged ZSM-S which was sulfided prior to use. Additional operating conditions as well as the results obtained are shown in the followi g tab e.
As can be seen from the above results, liquid yield is much higher and dry gas much lower in the presence of hydrogen.
EXAMPLES 28-34 The following table will show the fate of the paratfins that are converted. As can be seen, in all cases alkyl aromatics were increased.
G./100 g. charge 600 F. 655 F. 707 F. 805 F. 901 F. 917 F. 933 F.
Disappearance of 05+ parafiins 18.03 14. 04 14.34 12. 39 16. 22 18.21 18.24
Incremental 0 's 2. 74 1. 99 1. 99 1. 73 2. 53 1. 73 2. 73
Incremental alkyl benzene ring carbon 4. 96 3. 64 3. 96 4. 31 4. 35 6. 83 5. 49
Incremental alkyl benzene side chain 3. 54 2. 77 2. 67 1. 88 1. 41 2. 34 1. 22
Total. 14. 40 10. 94 11. 45 11. 45 14. 24 17. 00 17. 48
EXAMPLE 35 EXAMPLES 37-42 The following examples will illustrate a nickel H-ZSM- 5 zeolite used in Examples 3-23 and 25-34.
The following solutions were prepared:
(a) 1.0 lbs. of sodium aluminate containing 41.8 weight percent A1 0 and 25 lbs. of water;
(b) 79.9 lbs. of Q blend sodium silicate in 100 lbs. of water, i.e. 28.9 weight percent SiO 9.0 weight percent Na O, 62.1 weight percent H 0;
(0) 10.0 lbs. of tetrapropylammonium bromide and 50 lbs. of water;
(d) 7.97 lbs. of sulfuric acid in 24 lbs. of water.
Solution (c) was added to solution (b) and then solution (a) was added to a mixture of (c) and (b). Solution (d) was then added to the mixture of (a), (b), and (c) with rapid stirring. A gel was formed and the mixture was maintained at a temperature of from about 195-210 F. for approximately 267.5 hours until crystallization was complete and ZSM-S was formed. After filtration the wet cake was mixed with water, washed and then dried at 250 F. After drying it was calcined 3 hours at 700 F.
The calcined ZSM-S was then subjected to 4 l-hr. exchanges with 1.0 N ammonium nitrate solution at room temperature.
The ammonium exchanged zeolite was then subjected to a 4-hour exchange with a 0.5 N nickel nitrate solution at 190 F.
The exchapgematerial was then washed free of nickel solution, dried at 250 F., sized 30-60 mesh and then calcined for hours at 1000 F.
The calcined ZSM-S was then sulfided with a mixture of about 2 weight percent hydrogen sulfide in hydrogen at 750 F.
The catalyst contained 011 Weight percent sulfur, 0.32 Weight percent nickel and 0.02 weight percent sodium.-
EXAMPLE 36 tion (a) was added to a mixture of (c) and (b). Solution (d) was then added to the mixture of (c), (b), and (a) with rapid stirring. A firm gel was formed at the end of adding solution (d).
The gel was heated at a temperature of 200-210 F. for a total of 167 hours until a crystalline aluminosilicate identified as ZSM-S was formed.
A C reformate eflluent stream was simulated by the blending of 50% benzene with 25% n-hexane and 25% isohexane. The material was then contacted with various forms of ZSM-5 catalysts at 200 p.s.i. 15/1 molar hydrogen/ hydrocarbon ratio, at 4 LHSV, and 700 F. High conversion to eliminate the low octane number component and enrichment thereby of the high octane number were observed as follows:
Wt. percent conversion To compare the performance of ZSM-5 with previously known shape selective 5 A. catalysts, a nickel hydrogen erionite was contacted with the same synthetic reformate blend used in Examples 37-43 and the results are shown below:
Catalyst Ni/H/erionite Wt. percent conversion:
n-Hexane 85.4 Z-methyl pentane 3.1 Benzene 2.6
ZSM-S catalysts in H, Zn/H, and Ni/H forms are more active than nickel/H-erionite in cracking n-hexane, and unlike nickel/H/erionite, they also convert significantly more Z-methyl pentane and benzene. In the liquid product collected from the ZSM-5 runs large amounts of C alkylaromatics were found apparently the result of alkylation of benzene with the cracked fragments. A typical analysis of the liquid product collected at room temperature is shown as follows:
Composition of liquid product from Example 40:
Weight percent Z-methyl pentane 1.5 n-hexane 0.8 Benzene 12.2 Toluene 1.2 C aromatics 30.2 C aromatics 54.1
21 EXAMPLES 4447 To compare the performance of ZSM-5 with previously known shape selective acid cracking catalysts, a hydro gen T prepared by calcining an ammonium exchanged zeolite T was contacted with the same synthetic reformate blend used in Examples 37-42 and reactor eflluent was analyzed after on stream for 15 minutes and 3 hours, respectively.
The results are shown as follows:
These results demonstrated the remarkable activity and non-aging characteristics of H/ZSM-S without added hydrogenation/dehydrogenatin component under hydrocracking conditions. H/T, on the other hand, aged considerably in 3 hours.
EXAMPLE 48 This example will illustrate a typical preparation of zeolite ZSM-S used in Example 38.
22.9 grams SiO was partially dissolved in 100 ml. 2.18 N tetrapropylammonium hydroxide by heating to a temperature of about 100 C. There was then added a mixture of 3.19 grams NaAlO (comp: 42.0 wt. percent A1 0 30.9% Na O, 27.1% H O) dissolved in 53.8 ml. H O. The resultant mixture had the following composition: 0.382 mole SiO 0.0131 mole Al O 0.0159 mole Na O, 0.118 mole [(CH CH CH N] O, 6.30 moles H O. The mixture was placed in a Pyrex-lined autoclave and heated at 150 C. for six days. The resultant solid product was cooled to room temperature, removed, filtered, washed with 1 liter H 0 and dried at 230 F. A portion of this product was subjected to X-ray analysis and identified as ZSM-5. A portion of the product was calcined at 1000 F. in air for 16 hours and the following analyses were obtained:
This example will illustrate the general procedure for the preparation of H-ZSM-S used in Examples 37, 45 and 47 A ZSM-5 'zeolite was prepared in accordance with the general technique set forth in Example 48; it was then contacted with a saturated solution of ammonium chloride in order to replace the original cations associated therewith and thereafter washed with water, dried and calcined in air at about 1000 F. in order to convert it to the hydrogen form, i.e. H-ZSM-S.
22 EXAMPLE 50 A ZSM-S type catalyst was prepared following the general procedure of Example 48. The reaction composition and characteristics of the finished product are as follows:
Temp, C. 150 Time, days 5 Reaction composition:
SiO /AI O 29.1 Na O/Al O 1.19 TPA O/Al O 9 HgO/TPA O+Na O 47 Composition:
Na O, wt. percent 2.42 Na, wt. percent 1.8 A1 0 wt. percent 6.1 SiO wt. percent 90.6 SiO /Al O 25.2 Na O/AI O 0.65 Adsorption:
Cyclohexane, wt. percent 3.07 Normal hexane, wt. percent 9.88 H O, wt. percent 7.51
The above material was then calcined at about 1000" F. for 16 hours and divided into two portions (A and B). Portion A was exchanged with ml. of a 0.5 N aqueous solution of ammonium chloride at room temperature for one hour to form the ammonium salt. This was labeled Catalyst A1. Three grams of Catalyst Al was exchanged with 35 ml. of a 0.5 N 2.9/1 zinc/NH chloride solution at 109 F. for four hours. The material was then washed with water and dried in air to yield a catalyst having a zinc content of 0.9 weight percent and a sodium content of 0.2 weight percent. After calcination at 1000 F. for 16 hours, it was used in Example 39.
Portion B was treated with anhydrous ammonia (100 cc. per minute) at room temperature to reconstitute the NH, sites. This catalyst was labeled B1. Three grams of Catalyst B1 Was exchanged with a 0.5 N solution of zinc and ammonium chloride as above. The finished catalyst contained 1.2 weight percent zinc and 0.3 weight percent sodium. After calcination at 1000 F. for 16 hours, it was used in Example 41.
The catalysts used in Examples 40 and 42 were prepared in a similar manner except that a nickel salt was used to base exchange the zeolite instead of a zinc salt.
What is claimed is:
1. A process for upgrading reformate and reformer efiluent which comprises contacting a mixture containing the same together with hydrogen with a crystalline zeolitic having an X-ray diflfraction pattern as set forth in Table 1.
2. The process of claim 1 wherein said zeolitic material also has a hydrogenation/dehydrogenation function.
3. A process for upgrading reformate and reformer effiuent which comprises contacting a mitxure containing the same with zeolite ZSM-S.
4. The process for upgrading reformate and reformer effluent which comprises contacting a mixture containing the same with zeolite ZSM-8.
5. The process of claim 3 wherein the zeolitic material has a hydrogenation/dehydrogenation component associated therewith.
6. The process of claim 4 wherein the zeolitic material has a hydrogenation/dehydrogenation component associated therewith.
7. A process for upgrading petroleum charge stocks having a boiling point in the gasoline range which comprises contacting said charge in the presence of hydrogen with a crystalline aluminosilicate zeolite having an X-ray diffraction pattern set forth in Table 1.
8. The process of claim 7 wherein the zeolitic material has a hydrogenation/dehydrogenation component associated therewith.
9. The process of claim 8 wherein the zeolite is ZSM-S.
10. The process of claim 8 wherein the zeolite is ZSM-8.
11. The process of claim 9 wherein the ZSM-S has been based exchanged with ammonium or hydrogen cations.
12. The process of claim 10 wherein the 'zeolite ZSM-8 has been base exchanged with ammonium or hydrogen ions.
24 References Cited UNITED STATES PATENTS 4/1966 Kimberlin 208137 US. Cl. X.R.