US3668269A

US3668269A - A process for disproportionating paraffinic hydrocarbons to yield products containing iso-paraffinic hydrocarbons

Info

Publication number: US3668269A
Application number: US50330A
Authority: US
Inventors: Frank J Chloupek
Original assignee: Atlantic Richfield Co
Current assignee: Atlantic Richfield Co
Priority date: 1970-06-26
Filing date: 1970-06-26
Publication date: 1972-06-06
Anticipated expiration: 1989-06-06

Abstract

A process for disproportionating paraffinic hydrocarbons containing three to seven, four to five, carbon atoms in a hydrogen atmosphere to yield products containing iso-paraffinic hydrocarbons containing one more and hydrocarbons containing one less carbon fragment per molecule is disclosed. In the process, the paraffinic hydrocarbon is contacted in a hydrogen atmosphere at about 700* to 900* F. with a solid, acidic catalyst comprising a minor, catalytically effective amount of a platinum-group metal and containing a hydrogen or metal exchanged crystalline aluminosilicate having pores in the 8 to 15 A range and a mole ratio of silica-to-alumina of greater than about 2 to 1 and a solid oxide support. The catalyst can contain from about 1 up to about 85 weight percent of the crystalline aluminosilicate. A preferred oxide support is silica-alumina which can further contain a minor amount of alumina such as an activated alumina of the gamma family.

Description

United States Patent Chloupek 1 June 6, 1972 [s 1 PROCESS FOR DISPROPORTIONATING PARAFFINIC HYDROCARBONS TO YIELD PRODUCTS CONTAINING ISO- PARAFFINIC HY DROCARBONS Frank J. Chloupek, South Holland, Ill.

Atlantic Richiield Company, New York, NY.

221 Filed: June 26,1970- [21] Appl.No.: 50,330

[72] inventor:

[73] Assignee:

3,046,317 7/1962 Myers ..260/676 Primary Examiner-,-Delbert E. Gantz Assistant Examiner-J. Nelson Attorney-McLean, Morton and Boustead [57] ABSTRACT A process for disproportionating parafiinic hydrocarbons containing three to seven, four to five, carbon atoms in a hydrogen atmosphere to yield products containing iso-paraffinic hydrocarbons containing one more and hydrocarbons containing one less carbon fragment per molecule is disclosed. In the process, the parafiinic hydrocarbon is contacted in a hydrogen atmosphere at about 700 to 900 F. with a solid, acidic catalyst comprising a minor, catalytically effective amount of a platinum-group metal and containing a hydrogen or metal exchanged crystalline aluminosilicate having pores in the 8 to 15 A range and a mole ratio of silica-to-alumina of greater than about 2 to l and a solid oxide support. The catalyst can contain from about 1 up to about 85 weight percent of the crystalline aluminosilicate. A preferred oxide support is silica-alumina which can further contain a minor amount of alumina such as an activated alumina of the gamma family.

13 Claims, No Drawings PROCESS FOR DISPROPORTIONATING PNIC HYDROCARBONS TO YIELD PRODUCTS CONTAINING ISO-PARAFFINIC HYDROCARBONS The present invention relates to a process for converting paraffin feedstocks into more desirable gasoline range hydrocarbons. More particularly, the present invention relates to a process whereby parafiin hydrocarbons of three to seven, preferably four to five, carbon atoms are disproportionated in a hydrogen atmosphere to yield a product containing higher and lower molecular weight paraffins, in the presence of a solid, acidic catalyst containing a platinum-group metal and a crystalline aluminosilicate. Still more particularly, the present invention concerns a process whereby paraffin hydrocarbons of from three to seven, preferably four to five, carbon atoms are disproportionated in a hydrogen atmosphere to yield a product containing higher and lower molecular weight paraffins which differ from the feedstock by the addition or removal of one methylene (CH group. The products of higher molecular weight include isoparaffins as do the products of lower molecular weight of at least four carbon atoms.

In general, paraffins are noted for resistance to the chemical conversions and as a class are considered relatively unreactive with the lower molecular weight paraffins showing the greatest resistance to reactivity. Because of the lack of reactivity, paraffins, such as propane, butane, pentane, and the like, have found limited utility in chemical reactions or chemical processing although some of these paraffins can, for example, be cracked, isomerized, dehydrogenated, or alkylated, to produce more valuable products. For example, propane can be cracked to provide ethylene, with the loss of a methane fragment or dehydrogenated to propylene, for utilization as an olefin in subsequent transformations.

In general, the process of the present invention comprises disproportionating a paraffin hydrocarbon feed by contacting the feed with a highly acidic, platinum-group metal, crystalline aluminosilicate and solid metal oxide containing catalyst, under relatively moderate conditions of elevated temperature and pressure in a hydrogen atmosphere, to provide a product containing paraffins of higher and lower molecular weight.

, According to the present process, paraffin hydrocarbon feedstocks containing three to seven, preferably four to five, carbon atoms are reacted to provide iso-paraffin having one carbon atom more than the feed and paraffin having one carbon atom less than the paraffin hydrocarbon feed. As an example, two moles of butane may be reacted to provide one mole of propane and one mole of iso-pentane; pentane can be reacted to provide iso-butane and iso-hexane. By the present inventive process, a paraffin hydrocarbon of limited utility can be reacted to provide highly useful iso-paraffin products, particu larly iso-paraffins boiling in the gasoline range and which are useful as fuels, solvents, and the like.

In the instant process, the paraffin hydrocarbon feed, i.e., having three to seven, preferably four to five, carbon atoms per mole, and which can be n-parafiinic, iso-paraffinic or mixtures of nand iso-paraffinic, is introduced into a reaction zone, which can be, for example, a fixed bed catalytic reactor, where it is contacted in a hydrogen atmosphere with a solid, highly acidic platinum-group metal crystalline aluminosilicate and solid metal oxide-containing catalyst at an elevated temperature and pressure. The temperature will generally be in the range of about 700 to 900 F., preferably about 750 to 850 F The pressure will often be about 200 to 1,000 or more psig, but it is preferable to utilize pressures from about 300 to 600 psig. The feed is conveniently contacted with the catalyst at weight hourly space velocities (WI-ISV) of about 1 to 10, preferably about 4 to 8. The WHSV can be varied with the selection of the paraffin feed, the temperature, and the pressure, to give a high conversion level over an economic duration. The mole ratio of molecular hydrogen to parafiin hydrocarbon in the reaction zone is usually at least about 0.5:1 and may often vary from about 0.5 to 5:1, or more and preferably is about 1 to 2:1.

As a number of carbon atoms in the parafiin feed molecules increase, cracking is more likely to occur at a given temperature. In the instant process, cracking is an undesirable side reaction in direct conflict with the production of higher molecular weight paraffin which is a primary objective of the present invention. Cracking is also detrimental to catalyst activity and life due to the formation of coke on the catalyst. It is, therefore, desirable to operate the process of the present invention at temperatures which, while consonant with attaining high activity of the reaction and high conversion levels of the feed, are not substantially higher than necessary, in order to avoid excessive cracking. It is possible to operate the process at a temperature whereat disproportionation occurs readily while little cracking takes place. Since cracking activity is favored at higher temperatures, the temperature is, accordingly desirably maintained at the lower end of the range providing for disproportionation of a given feed, that is, at a temperature effective to avoid substantial or significant cracking of the feed. Since the reactivities of paraffin feeds vary with the number of carbon atoms per molecule, the specific temperature desired, may, of course, vary with the feed chosen. Generally, the fewer carbon atoms per molecule of the feed, the higher the temperature required to attain satisfactory disproportionation activity, and the higher the temperature which can be tolerated without significant cracking.

A second reaction of impact on the reaction of the present invention is isomerization since the catalysts used are relatively active for this reaction. It has been found, however, that disproportionation selectivity is generally higher for branchedchain paraffin hydrocarbons than for n-paraffins, suggesting that it is the branched isomers which disproportionate and that in this invention an n-paraffin feed is first isomerized to a branched-chain isomer which, in turn, disproportionates.

The paraffin hydrocarbon feedstock converted in the process of the present invention can be substantially a single paraffin such as butane, or can be a mixture of paraffins, such as butane and pentane. The feed can be n-paraffins, iso-paraffins or a mixture of n-paraffins and iso-paraffins. The feed may be derived from petroleum fractions, such as are found in various petroleum refinery streams and can be separated in more or less pure form. Desirably, large amounts of olefins are excluded from the feed and, preferably, the feed will contain not more than about 5% by weight of olefins. Feeds essentially olefin-free are particularly desirable. Among the paraffin hydrocarbons suited for the process of the present invention are propane, n-butane, isobutane, n-pentane, isopentane, 2,2- dimethyl propane, n-hexane, iso-hexane, nheptane and isoheptane.

The catalyst in the disproportionation reaction of this invention contains a minor, catalytically effective amount, e.g., about 0.01 to 5 percent by weight of the total catalyst, preferably about 0.05 to 1 percent, of one or more of the platinum group metals; and a catalytically effective amount, e.g., from about I to 85 percent by weight of the total catalyst, preferably from about 5 to 45 or even weight percent, of a crystalline aluminosilicate having a mole ratio of silica-to-alumina of greater than 2:1, e.g., from about 2:1 to 12:1, preferably from about 4:1 to 6: 1; and a solid metal oxide support, e.g., one or more of the refractory metal oxides of the metals of Groups II to IV of the periodic chart such as silica, alumina, titania, zirconia and magnesia or their mixtures. The support can further contain minor amounts or other materials added to impart a particular property to the catalyst without being significantly deleterious in other respects. Such support is often at least about 10, e.g., about 10 to 98.9 weight percent, preferably about 20 to 94.5 percent of the catalyst. In many cases, the oxide support may be the major proportion of the catalyst.

The crystalline aluminosilicate of the catalyst can be either a synthetic or naturally occurring crystalline aluminosilicate having not more than about 0.5 equivalents of alkali metal per gram atom of aluminum in the crystalline aluminosilicate, and

pores having diameters of about 8 to 15 A, preferably about 10 to 14 A, as in the case of the faujasite type, Usually, with a particular source of material, the pores are of relatively uniform size. The aluminosilicate particles may have an ultimate crystal size of about 0.5 to 15 microns, preferably about 0.5 to 1.5 microns. The silica-to-alumina more ratio of the crystalline aluminosilicate is greater than 2:1, and is usually not above about 12:1, preferably being about 4 to 6:1.

Crystalline aluminosilicates are available in a number of synthetic and naturally occurring alkali metal forms. For example, sodium crystalline aluminosilicates often have a sodium oxide-to-alumina ratio of about 0.7 to l.l:l. Synthetic crystalline aluminosilicates are ordinarily prepared in alkali metal form. The alkali metal serves as a catalyst poison in the present invention and undue amounts should not be present in the catalyst used in the disproportionation reaction. In the catalyst of the present invention, therefore, at least partial replacement of the alkali metal by hydrogen or by a polyvalent metal cation is necessary to provide less than about 0.5 equivalents of alkali metal per gram atom of aluminum in the aluminosilicate.

The crystalline aluminosilicate component of the catalyst utilized in the present invention can, for example, be prepared by base-exchanging the alkali metal crystalline alumino-silicate by treatment with a solution characterized by a pH in excess of about 3, preferably by a pH in the range ofabout 4.5 to 10, and containing hydrogen or a hydrogen precursor capable of replacing the alkali metal. After treating to effect the exchange, the resultant base-exchanged material is washed free of water-soluble material, and the base-exchanged material is dried and subjected to a thermal activating treatment. The alkali metal content of the finished crystalline aluminosilicate component of the catalyst is often less than about 4, preferably less than about 1, weight percent. The alkali metal aluminosilicate may be calcined prior to base-exchange in an atmosphere which does not adversely affect the aluminosilicate, such as air, nitrogen, hydrogen, flue gas, helium, or other inert gas, at a temperature in the range of about 500 to l,500 F.

The base-exchange required to introduce the necessary cations is carried out for an adequate period of time, a sufficient number of times, and at appropriate temperatures to effect replacement of at least about 50 weight percent, preferably about 60 to 90 weight percent, of the alkali metal originally contained in the aluminosilicate and to effectively reduce the alkali metal content ofthe resulting crystalline aluminosilicate component of the catalyst to below about 4 weight percent, preferably below about 1 weight percent. Stated another way, the finished catalyst contains less than about 0.5, preferably about 0.25, equivalents of alkali metal per gram atom aluminum in the aluminosilicate.

It is contemplated that various ionizable compounds of hydrogen, hydrogen ion precursors, e.g. ammonium ions and the like, or of metals such as silver, copper, mercury and polyvalent metals can be used. The preferred polyvalent metals to be associated with the crystalline aluminosilicate employed as the catalyst of the present invention are the metals of Group IIA of the Periodic Table, e.g., magnesium and calcium. Also particularly suitable are the rare earth metals, including cerium. The metals can be used either singly or in combinations among themselves or with hydrogen ion precursors. Compounds are used in the exchange where the polyvalent metal or hydrogen precursor is present as a cation. Inorganic salts will usually be employed, although organic salts, such as acetic and formate can also be used.

While water will ordinarily be the solvent in the baseexchange solutions used, it is contemplated that other solvents, although generally less preferred, can be used. Thus, in addition to aqueous solutions, alcoholic solutions and the like of suitable compounds can be employed in producing the catalyst utilized in the present invention. It will be understood that the compounds employed for the base-exchange solution undergo ionization in the particular solvent employed in the preparation.

The concentration of the compound employed in the baseexchange solution can vary, depending on the nature of the particular compound, on the alkali metal crystalline aluminosilicate undergoing treatment, and on the conditions under which the treatment is effected.

The temperature at which the base-exchange is effected may vary widely, generally ranging from room temperature to an elevated temperature below the boiling point of the treating solution. The volume of the base-exchange solution employed may vary widely, although generally an excess is employed and such excess is removed from contact with the crystalline aluminosilicate after a suitable period of contact. The time of contact between the base-exchange solution and the crystalline aluminosilicate in any instance, whether by a single or a plurality of successive contacts, is such as to effect displacement of the alkali metal ions to an extent such that alkali metal content of the catalyst after base-exchange is satisfactorily reduced. It will be understood that such period of contact may vary, depending on the temperature of the solution, the nature of the crystalline aluminosilicate, and the particular compound employed for the base-exchange. Thus, the period of contact may extend from a brief period on the order of a few hours for small particles to longer periods on the order of several days for large pellets.

After the base-exchange treatment, the crystalline aluminosilicate component of the catalyst is removed from the treating solution. Superfluous materials, such as anions introduced as a result of the treatment, are removed by waterwashing the treated composite. The washed product is then dried, generally in air, to remove substantially all the water. While drying can be conducted at ambient temperatures, it is generally more satisfactory to facilitate the removal of moisture by maintaining the material at a temperature between about 150 and 600 F. for about 4 to 48 hours.

The dried material is then subjected to an activating treatment, essential to establish the catalytic activity of the composition. Such treatment entails heating the dried material in an atmosphere which does not adversely affect the crystalline aluminosilicate component of the catalyst, such as air, nitrogen, hydrogen, flue gases, helium, or other inert gas. The dried material can be heated, in air for example, to a temperature in the approximate range of about 500 to 1,500 F. for a period of at least about 1 hour, and usually about one to 48 hours.

The active aluminosilicate component prepared in the foregoing manner can be combined, dispersed or otherwise intimately admixed with the support in such proportions that the resulting product contains, for instance, from about 1 to weight percent, preferably about 5 to 80 weight percent, of the active aluminosilicate in the final composite.

The porous oxide support component of the catalyst is usually comprised of a metal oxide or a mixture of metal oxides, the metals of which are often selected from Groups ll to IV of the periodic chart. Examples of such metal oxides are silica, alumina, titania, zirconia, magnesia and their mixtures. It is preferred that the catalyst base contain both silica and alumina in the oxide form of relatively high acidity. The support can thus contain a major amount, of, for example, about 60 to 99 weight percent, preferably 80 to 95 weight percent, of amorphous silica-alumina. The support can further contain a minor amount of, for example, 1 to 40 weight percent, preferably 5 to 15 weight percent of alumina, especially an activated alumina of the gamma-alumina family such as gamma-, etaor chi-alumina. Minor amounts of other materials can also be added to the support to impart a particular property to the catalyst without being significantly deleterious in other respects.

A solid support advantageous for use in the catalyst of the present invention is an acidic, silica-based material, e.g. having a D L activity of at least about 20, preferably at least about 30 when determined according to the method of Birkhimer et al., A Bench Scale Test Method for Evaluating Cracking Catalysts," Proceedings of the American Petroleum Institute, Division of Refining, Vol. 27 (III), page (1947) and hereinafter referred to as Cat. A. The silica-based support preferably has a substantial surface area as determined by the BET nitrogen absorption procedure (JACS, Vol. 60, pp. 309 et seq. (1938). The surface area of the support can be at least about 50 square meters per gram, and surface areas are often up to about 500 or more m /gm, preferably about 150 to 400 m /gm. It is preferred that the catalyst support be relatively dry to avoid undue reaction with and loss of catalytic promoting materials. Thus, it is advantageous that the support be calcined, e.g. at temperatures of about 600 to 1,500 E, or more, to reduce the water content, but such calcination should not be so severe that the support is no longer catalytically active.

The support component can contain other materials in addition to silica which materials, when combined with silica, provide an acidic material as'in, for instance, the case of silicaalumina. Often these materials are one or more oxides of the metals of Groups II, III and IV of the Periodic Table. Examples of the composite contemplated herein under the generic designation of silica-based materials are often composed predominately of or even to. a major extent of silica. These supports include, for example, silica-alumina, silica-boria, silica-zirconia, silica-magnesia, silica-alumina-zirconia, silicaalumina-thoria, silica-alumina magnesia, and the like. The support often contains silica and alumina and such supports, whether naturally-occurring as in acid-treated clays, or a synthetic gel, will frequently contain about to 60, preferably about to 45, weight percent alumina. In addition, such silica-alumina supports can, and preferably do, contain a portion of the alumina as a separate, distinct phase.

A preferred catalyst support can be made by combining a silica-alumina hydrogel with a hydrous alumina. An advantageous hydrous alumina component is, when analyzed by X-ray diffraction of dry samples, either one or a mixture of amorphous hydrous alumina and a monohydrate, e.g., boehmite, of less than about 50 A, preferably less than about 40 A, crystallite size as determined by half-widthmeasurements of the (0, 4, 1) X-ray diffraction line-calculated by the Debye-Scherrer equation.

The mixture of the catalyst precursor components can be dried, e.g., at about 220 to 500 F., preferably about 800 to l,400 F to provide the active catalyst support. During calcination, the separate hydrous alumina phase of the mixture is converted to a gamma form or other catalytically active alumina.

In providing the preferred catalyst support precursor for drying, the components can be combined in any suitable manner or order desired, and advantageously, each of the components is in the mixture in finelydivided form, preferably the particles are principally less than about 300 mesh in size. The finely-divided material can have an average particle size of about 10 to 150 microns and can be used to make a catalyst of this particle size which can be employed in a fluidized bed type of operation. However, if desired, the mixture of catalyst support components can be placed in macrosized form, that is, made into particles as by tabletting, extruding, etc., to sizes of the order of about one sixty-fourth inch to one-half inch or more in diameter and about one thirty-second inch to 1 inch or more in length, before or after drying or calcination. If the formation of the macrosized particles is subsequent to calcination and the calcined particles have been contacted with water, the material can be recalcined.

On a dry basis, the preferred supports of the catalyst of the present invention contain about 45 to 95 weight percent of the amorphous s'ilica'alumina xerogel and about 5 to weight percent of the separately added alumina phase. The alumina content from the silica-alumina xerogel and the separate alumina phase is about 20 to 70 weight percent, preferably about 25 to weight percent, based on the dried support. Also, the catalyst support generally contains less than about 1.5 weight percent, preferably less than about 0.5 weight percent, sodium.

The silica-alumina component of the precursor of the preferred catalyst support of the present invention can be silica-alurnina hydrogel which contains about 55 to 90, preferably about 25to 35, weight percent alumina, on a dry basis. The silica-alumina can be naturally occurring or can be synthetically prepared by any desired method and several procedures are known in the art. For instance, an amorphous silica-alumina hydrogel can be prepared by co-precipitation or sequential precipitation by either component being the initial material with at least the principal part of the silica or alumina being made in the presence of a silica gel. It is preferred that the silica-alumina hydrogel be made by forming a silica hydrogel by precipitation from alkali metal silicate solution and an acid such as sulfuric acid. The alum solution may be added to the silica hydrogel slurry. The alumina is then precipitated by raising the pH into the alkaline range by the addition of an aqueous sodium aluminate solution or by the addition of a base such as ammonium hydroxide. Other techniques for preparing the silica-alumina hydrogel are well known in the art, and these techniques may be used in the practice of the invention.

The alumina hydrogel which can be combined with the silica-alumina is made separately from the silica-alumina. The alumina hydrogel may be prepared, for example, by precipitation of alumina at alkaline pH by mixing alum with sodium aluminate in an aqueous solution or with a base such as soda ash, ammonia, etc. As noted above, the alumina hydrogel can be in the form of amorphous hydrous alumina or alumina monohydrate, e.g., of up to about 50 A crystallite size as determined by X-ray diffraction analysis. The amorphous hydrous alumina generally contains as much combined water as does an alumina monohydrate. Mixtures of the monohydrate and amorphous forms of hydrous alumina are preferred and often this phase is composed of at least about 25 percent of each of the separate members.

In preparing the catalyst, the solid metal oxide support material and crystalline aluminosilicate can be intimately mixed together or alternatively, and particularly when the support contains two or more solid metal oxide components, such as a mixture of silica-alumina and alumina, the silica-alumina and the alumina may be intimately mixed, for instance, by colloidal milling. The crystalline aluminosilicate can be added after the milling, and alternatively, this ingredient can also be combined before the colloidal milling operation. The mixture is dried, water washed to acceptable concentrations of, for instance, sodium, and redried in the preferred procedure. The drying, especially the initial drying, is advantageously effected by spray drying to give microspheres. The combined materials can also be shaped as by extrusion into suitable shapes.

The dried catalyst support and crystalline aluminosilicate mixture can then be contacted with an aqueous solution of a water soluble platinum-group metal compound, such as chloroplatinic acid, to impregnate the platinum-group metal compound into the support. The impregnated support can then be dried and heated to convert the compound to the metal. Platinum is the preferred metal and chloroplatinic acid is the preferred platinum compound.

The following examples further illustrate the process of this invention:

EXAMPLE I A platinum-metal containing catalyst is prepared by combining 15 weight percent of a synthetic faujasite type, hydrogen-form crystalline aluminosilicate substantially completely hydrogen-exchanged and having pores of about 13 A and a silica-to-alumina mole ratio of about 5 to l, with a support composed of about 75 weight percent amorphous silica-alumina, balance alumina. The catalyst materials are extruded into one-sixth inch in diameter cylinders and impregnated with a solution of chloroplatinic acid, dried and calcined. The catalyst contains about 0.5 weight percent platinum.

20 grams of the platinum-metal, crystalline aluminosilicatecontaining catalyst is charged to a universal type reactor. Isobutane is introduced from a pressurized blow case. The conditions employed and the results of the analysis of the products appear in Table I.

TABLE 1 Run No. 1 2 3 6 Feed i-C i-C i-C i-C i-C WHSV 2.0 2.0 4.0 2.0 8.0 Temp. F. 750 850 850 850. 850 Press., psig 300 300 300 300 500 H IH'C 1 1 1 5 1 Conv. 46.55 54.73 47.73 63.77 51.81

Selectivities Disproportionation 30.48 26.55 25.58 24.59 31.81 L/H 1.530 1.784 1.504 1.644 1.555 lsomerization 63.35 65.56 68.23 69.81 61.49 Disproportionation and lsomerization 93.83 92.11 93.81 94.40 93.30

'H,/HC Hydrogen to hydrocarbon ratio. L/H light to heavy mole fraction C ,/C,.

EXAMPLE 11 A platinum-metal containing catalyst is prepared by combining 80 weight percent of the synthetic faujasite-type hydrogen-form crystalline aluminosilicate of Example I with 20 weight percent of alumina monohydrate. The catalyst materials are extruded into one-sixteenth inch diameter cylinders and impregnated with a solution of chloroplatinic acid, dried and calcined. The catalyst contains about 0.5 weight percent platinum.

20 grams of the catalyst is charged to a Universal type reactor. Isobutane is introduced from a pressurized blow case. The conditions employed and the results of the analysis of the Two platinum-metal-, crystalline aluminosilicate-containing catalysts are prepared.

The first catalyst is prepared by combining 15 weight percent of a synthetic faujasite-type crystalline aluminosilicate having been substantially completely calcium-exchanged and having pore sizes of about 13 A and a silica-to-alumina mole ratio of about 5 to 1, with a support composed of about 75 weight percent amorphous silica-alumina, balance alumina. The catalyst materials are extruded into one-sixteenth inch diameter cylinders and impregnated with a solution of chloroplatinic acid, dried and calcined. The catalyst, hereinafter designated Cat. A, contains about 0.5 weight percent platinum.

The other catalyst is prepared by combining weight percent of the calcium-exchanged crystalline aluminosilicate described above for Cat. A with about 20 weight percent of alumina monohydrate. These catalyst materials are also extruded into one-sixteenth inch diameter cylinders and impregnated with a solution of chloroplatinic acid, dried and calcined. The catalyst, hereinafter designated as Cat. B, contains about 0.5 weight percent platinum.

20 grams of each of Cat. A and Cat. B are charged to a Universal type reactor. Isobutane is introduced from a pressurized blow case. The catalysts are compared for average relative activity (Table 111), and a comparison of the isomerization and disproportionation activities at constant conversion (Table IV). Tables V and VI also show the effects of pressure and space velocity on the reaction. The conditions employed and results of the analysis of products are listed below in Tables 111 to V1.

TABLE III Catalyst Cat. A Cat. B Feed i-C i-C WHSV 4 4 Temp., F. 850 850 Press, psig 300 300 H /H'C 1 1 Average Relative Activity 2.14 2.65

TABLE IV Catalyst Cat. A Cat. 8 Feed i-C,, i-C. WHSV 4 4 Temp., F. 850 850 Press, psig 500 500 H /HC 1 1 Conversion 65 65 Selectivities Disproportionation 32.27 27.45 lsomerization 46.98 58.58 Disproportionation and lsomerization 79.25 86.03

TABLE V Catalyst Cat. A Cat. B Cat. A Cat. 8 Feed i-C i-C, i-C i-C WHSV 4 4 4 4 Temp., F. 850 850 850 850 Press, psig 300 300 500 500 H /HC 1 1 1 1 Conversion 47.69 62.70 65.90 75.71

Selectivities Disproportionation 25.58 27.93 32.27 22.67 L/H 1.50 2.22 2.07 4.49 %1somerization 68.23 59.17 46.98 47.34 Disproportionation and lsomerization 93.81 87.10 79.25 70.01

TABLE VI Catalyst Cat. A Cat. B Cat. A Cat. B Feed i-C, i-C i-C i-C WHSV 4 4 8 8 Temp., F. 850 850 850 850 Press, psig. 500 500 500 500 H /H'C l l l 1 Conversion 65.90 75.71 57.81 64.56

Selectivities Disproportionation 32.27 22.67 31.8l 27.45 L/l-l 2.07 4.49 1.56 2.34 Isomerization 46.98 47.34 61.49 58.58 Disproportionation and lsomerization 79.25 70.0l 93.30 86.03

it is claimed:

1. In the process for the disproportionation of feed paraffin hydrocarbon containing four to five carbon atoms per molecule to produce product isoparafiin hydrocarbon containing one more carbon atom per molecule than said feed paraffin hydrocarbon and product parafiin containing one less carbon atom per molecule than said feed paraffin hydrocarbon, the improvement which comprises contacting said feed paraffin hydrocarbon in a hydrogen atmosphere at a temperature of from about 700 to 900 F. with a solid, acidic catalyst consisting essentially of a minor, catalytically effective amount of a platinum-group metal and a catalytically effective amount of a crystalline aluminosilicate having less than about 0.5 equivalents of alkali metal per gram atom of aluminum, a mole ratio of silica-to-alumina of greater than about 2:1 and pores having diameters of about 8 to A, and at least about 10 weight percent of solid metal oxide catalyst support comprising at least one refractory metal oxide of the metals of Groups II to IV of the periodic chart.

2. The process of claim 1 wherein said contacting is conducted at a temperature of from about 750 to 850 F., and a pressure of from about 200 to 1,000 psig.

3. The process of claim 1 wherein the catalyst contains from about 1 to weight percent of the crystalline aluminosilicate.

4. The process of claim 3 wherein the catalyst contains from about 0.05 to 1 weight percent platinum and about 5 to 80 weight percent of the crystalline aluminosilicate.

5. The process of claim 3 wherein the catalyst support contains from about 60 to 99 weight percent of amorphous silica alumina and from about 1 to 40 weight percent activated alumma.

6. The process of claim 4 wherein the catalyst support contains from about 80 to weight percent of amorphous silica alumina and from about 5 to 15 weight percent of activated alumina.

7. The process of claim 1 wherein the activated alumina is one of the gamma-alumina family.

8. The process of claim 5 wherein the activated alumina is one of the gamma-alumina family.

9. The process of claim 1 wherein said feed paraffin hydrocarbon comprises n-paraffins and isoparaffins.

10. The process of claim 3 wherein the catalyst support is alumina monohydrate.

11. The process of claim 3 wherein said feed paraffin hydrocarbon is isobutane.

12. The process of claim 6 wherein said feed paraffin hydrocarbon is isobutane.

13. The process of claim 10 wherein said feed paraffin hydrocarbon is isobutane.

Claims

2. The process of claim 1 wherein said contacting is conducted at a temperature of from about 750* to 850* F., and a pressure of from about 200 to 1,000 psig.
3. The process of claim 1 wherein the catalyst contains from about 1 to 85 weight percent of the crystalline aluminosilicate.
4. The process of claim 3 wherein the catalyst contains from about 0.05 to 1 weight percent platinum and about 5 to 80 weight percent of the crystalline aluminosilicate.
5. The process of claim 3 wherein the catalyst support contains from about 60 to 99 weight percent of amorphous silica alumina and from about 1 to 40 weight percent activated alumina.
6. The process of claim 4 wherein the catalyst support contains from about 80 to 95 weight percent of amorphous silica alumina and from about 5 to 15 weight percent of activated alumina.
7. The process of claim 1 wherein the activated alumina is one of the gamma-alumina family.
8. The process of claim 5 wherein the activated alumina is one of the gamma-alumina family.
9. The process of claim 1 wherein said feed paraffin hydrocarbon comprises n-paraffins and isoparaffins.
10. The process of claim 3 wherein the catalyst support is alumina monohydrate.
11. The process of claim 3 wherein said feed paraffin hydrocarbon is isobutane.
12. The process of claim 6 wherein said feed paraffin hydrocarbon is isobutane.
13. The process of claim 10 wherein said feed paraffin hydrocarbon is isobutane.