MXPA00008776A - Zeolite catalyst activity enhancement by aluminum phosphate and phosphorus - Google Patents

Abstract

The present invention provides a process for improving thecatalytic activity of small and medium pore acidic zeolite catalyst which comprises the steps of treating a zeolite with a phosphorus compound to form a phosphorus treated zeolite and combining the phosphorus treated zeolite with A1PO4. Optionally the phosphorus treated zeolite is calcined. The step of combining the zeolite with A1PO4 may optionally be followed by steaming the combined catalyst. Examples of useful phosphorus containing compounds useful in treating the zeolite include phosphoric acid, ammonium mono or dihydrogen phosphate, organic phosphites, and organophosphines. Preferably the phosphorus containing compound is an ammonium acid phosphate. An additional alternate embodiment provides a process for increasing the hydrothermal stability of a zeolite catalyst which comprises first treating a zeolite with a phosphorus containing compound then blending with A1PO4. The catalyst of the invention may be combined with other catalysts or used alone. The invention may be used in a process for cracking hydrocarbons which comprises contacting a hydrocarbon feedstock with a catalyst prepared as described above.

Description

INCREMENT OF ACTIVITY OF ZEOLITE CATALYST THROUGH ALUMINUM PHOSPHATE AND PHOSPHORUS Technical Field The invention provides a process for increasing the hydrothermal activity and stability of zeolite catalysts by the addition of aluminum phosphate and phosphorus to small and medium pore acid zeolites. Background The thermal and catalytic conversion of hydrocarbons into olefins is an important industrial process that produces millions of pounds of olefins each year. Due to the large volume of production, small improvements in operating efficiency translate into significant gains. Catalysts play an important role in the more selective conversion of hydrocarbons into olefins. Particularly important catalysts are found among natural and synthetic zeolites. Zeolites are crystalline aluminosilicates with a network of tetrahedra of A104 and Si04 linked by means of oxygen atoms. The negative charge of the network is balanced by the inclusion of protons or cations, such as alkali metal or alkaline ferrous ions. The interstitial spaces or channels formed by the crystalline network allow zeolites to be used as molecular sieves in separation processes and in catalysis. There are a large number of zeolitic structures, both natural and synthetic, including materials with additional elements such as boron, iron, gallium and titanium. The wide diversity of zeolite structures is illustrated in the "Atlas of Zeolite Structure Types", by .M. Meier, D.H. Olson and Ch. Baerlocher (4th edition, Elsevier / Intl. Zeolite Assoc. (1996)). Catalysts containing zeolites, especially medium pore zeolites, are known to be active in the disintegration of light naphtha to light olefins, mainly propylene and butylenes, as well as heavier hydrocarbon streams. Of particular interest are zeolites of proton form, effective for conversion of hydrocarbons such as naphthas into olefins. Typical catalysts include zeolite ZSM-5, described and claimed in U.S. Patent No. 3,702,886, and zeolite ZSM-11, described in U.S. Patent No. 3,709,979, and the numerous variations of these disclosed catalysts and claims in later patents. It has been previously observed that the treatment or addition of either phosphorus or aluminum phosphate separately produced a small improvement in certain zeolite catalysts. U.S. Patent No. 4,605,637 teaches the activation of low acidity zeolite with an aluminum phosphate in contact with an aqueous liquid phase. U.S. Patent No. 4,977,122 teaches the use of phosphorus containing alumina to increase the activity of catalysts. U.S. Patent No. 5,378,670 discloses the use of phosphorus compounds to activate zeolites. U.S. Patent No. 5,457,078 teaches a method for manufacturing improved zeolite beta catalyst wherein a substantially free crystalline aluminum phosphate matrix is generated by treating the zeolite and an acid-soluble aluminum source, such as pseudoboehmite, with a phosphorus compound such as phosphoric acid. The resulting mixture is spray-dried or extruded and can optionally be calcined. In one example, ZSM-5 is used. However, the composition is specifically described and claimed as a matrix that is substantially free of crystalline aluminum phosphate. The technique has not previously recognized the synergistic effect of phosphorus and aluminum phosphate in combination with small and medium pore acid zeolites. In contrast to the teachings of U.S. Patent No. 5,457,078, which teaches the use of a catalyst substantially free of crystalline aluminum phosphate, the inventors of the present invention found that a combination that includes medium and small pore acid zeolites treated with phosphorus of aluminum and phosphorus provides a catalyst of disintegration (cracking) synergistically improved, with improvements considerably greater than the sum of the improvements indicated with any of the components alone. SUMMARY The present invention provides a process for improving the catalytic activity and hydrothermal stability of small and medium pore acid zeolite catalysts, comprising the steps of treating a zeolite with a phosphorus compound to form a phosphorus treated zeolite and combining the zeolite treated with phosphorus with A1P04. Optionally, the zeolite treated with phosphorus is calcined. The step of combining the zeolite with A1P04 can optionally be followed by applying steam to the combined catalyst. Examples of phosphorus-containing compounds useful in the treatment of zeolite include phosphoric acid, or an acid salt thereof, such as mono- or di-hydrogenated ammonium phosphate, organic phosphites, and organic phosphines. Preferably, the phosphorus-containing compound is an ammonium acid phosphate. Any of the medium pore and small pore, crystalline, natural or synthetic zeolites can be improved by the treatment according to the invention. These zeolites and their isotopes are described in the "Atlas of Zeolite Structure Types", editors .H. Meier, D.H. Olson and Ch. Baerlo-cher, Elsevier, 4a. edition, 1996, which is incorporated by reference. A zeolite of average pore size has a pore size of about 5X to about 7X, and includes, for example, zeolites of structure type MFI, MEL, MTW, EUO, MTT, FER, MFS and TON [using the nomenclature of the International Union of Pure and Applied Chemistry (IUPAC) Commission of Zeolite Nomenclature]. Examples of medium pore size zeolites, corresponding to the structure types listed above, include ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM- 48, ZSM-50, ZSM-57, MCM-22, silicalite-1 and silicalite-2. A small pore size zeolite has a pore size of about 3X to 5X and includes, for example, zeolites of structure type CHA, ERI, MAZ, OFF, RHO, HEV, KFI, LEV and LTA (IUPAC Commission of Zeolite Nomenclature). Examples of small pore zeolites include ZK-4, SAPO-34, SAPO-35, ZK-14, SAPO-42, ZK-21, ZK-22, ZK-5, ZK-20, zeolite A, erionite, chabazite, T zeolite, gmelinite, ALPO-17, clinoptilolite, mazzite, offretite, heulandite and rho zeolite. In a preferred embodiment, the zeolite catalyst comprises ZSM-5. An alternative embodiment provides a process for increasing the catalytic activity of a zeolite catalyst comprising first treating a zeolite with a phosphorus-containing compound, then mixing with AlP04. In an alternative embodiment, the invention is a catalyst having a composition of 0.5-10% P / l-50% AlP04 / 5-60% zeolite, the remaining amount to provide 100%, if any, being a material binder. The binder can be any suitable material. Preferably, the binder is selected from the group consisting of kaolin, silica, alumina or mixed oxides; preferably, the composition is 1-2% P / 3-5% AlP04 / 35-55% zeolite / 38-61% binder, more preferably 1% P / 4% AlPO4 / 40% zeolite / 55% binder. The catalyst of the invention can be combined with other catalysts or used alone. The invention can be used in a process for disintegrating (cracking) hydrocarbons, comprising contacting a hydrocarbon feedstock with a catalyst prepared as described above, under conditions of catalytic decay (cracking). Alternatively, the invention provides a method for improving the stability of a catalyst over time, as compared to an untreated zeolite catalyst of the same type. Detailed Description of the Invention Examples of medium and small pore zeolites useful in the claimed process include gallium silicate, rho zeolite, ZK-5, titanosilicate, ferrosilicate, borosilicate zeolites, or natural crystalline zeolites such as chabazite, erionite, mazzita, offretita, gmelinita, etc. Suitable catalysts for treatment according to the invention are among the medium and small pore zeolites. As used herein, the term "medium and small pore zeolites" also includes zeolites having 10 or 8 member pore structures respectively. These zeolites can be produced with molar ratios other than silica to alumina, which vary from 2: 1 upwards. In fact, they have been produced from reaction mixtures from which alumina is intentionally excluded, in order to produce materials that have extremely high silica to alumina ratios that, in theory at least, can extend to infinity, before treatment according to the invention. Preferred medium pore zeolites include ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-35, ZSM-48 and MCM-22. Particularly preferred is ZSM-5. Preferred small pore zeolites include crystalline aluminosilicate zeolites such as erionite, chabazite, ferrierite, heulandite, and their synthetic counterparts such as zeolites A and ZK-5. Preferably the zeolites have a silica to alumina ratio in the range of about 2.0: 1 to 2,000: 1. More preferably, the zeolite catalyst has a structure type selected from the group consisting of MFI, EL, MTW, EUO, MTT, FER, MFS, TON, CHA, ERI, MAZ, OFF, RHO, HEV, KFI, LEV and LTA. In a preferred alternative, the zeolites to be treated are selected from the group consisting of ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, ZSM- 50, ZSM-57, MCM-22, silicalite-1, silicalite-2, ZSK-4, SAPO-34, SAPO-35, ZK-14, SAPO-42, ZK-21, ZK-22, ZK-5, ZK-20, zeolite A, erionite, chabazite, zeolite T, gmelinite, ALPO-17, clinoptilolite, mazzite, offretite, heulandite, and rho zeolite. A specially favored zeolite is ZSM-5. The phosphorus can be added to the zeolite by any conventional means, such as by physically mixing the zeolite with an aqueous solution of a phosphorus compound, such as a phosphate salt or phosphoric acid. Acid ammonium phosphates are the preferred sources of phosphorus. Following the treatment with the phosphorus solution, the zeolite can be calcined before combining it with dry or wet aluminum phosphate gel or the aluminum phosphate can be formed in itself as by treatment of an aluminum compound, such as alumina, and the zeolite, with a suitable phosphorus-containing reagent, such as a phosphate solution. The order of the physical mixture is important, the phosphorus treatment occurring before the addition of aluminum phosphate. In preferred embodiments, the catalyst also includes a binder such as silica, alumina or clay. The improved phosphorus-treated aluminum phosphate / zeolite catalyst can be used alone or physically mixed with another catalyst to achieve the desired degree of improved conversion. For example, the zeolite / phosphate aluminum catalyst treated with phosphorus, with or without a binder, can be added to a bed of fluid catalytic cracking catalyst in combination with a conventional FCC catalyst, to improve the conversion in the unit. In another embodiment, the invention also provides a method for treating phosphorus with a zeolite which, when combined with aluminum phosphate, produces a catalyst that also exhibits improved hydrothermal stability relative to an untreated zeolite catalyst of the same type in a mixture with the same amount of aluminum phosphate. Suitable hydrocarbons when practicing the present invention would include any feedstock that typically feeds catalytic disintegrators. Examples are butane, naphthas, gasoils, Fischer-Tropsch liquids, refined, natural field gasolines, petroleum waxes and vacuum gas oil. Additional feedstocks include streams containing olefins or diolefins such as butenes, butadienes, naphthas disintegrated with steam, coker naphthas. Preferred hydrocarbons are light naphthas, catalytic light naphtha, unhydrogenated C4 to C6 compounds of normal water vapor disintegrant effluent, vacuum residues, or portions of the effluent from a catalytic disintegrator as recycle. When the catalyst is used in a process to disintegrate (cracking) hydrocarbons, the temperature in the catalytic reactor is optimized to achieve the different desired product ratios, such as ethylene or propylene, as desired, with a normal range of operating temperature from around 500 to 750 'C; more preferably, in the range of 500 to 650 'C; most preferably, in the range of 500 to 600 'C. The process of contacting the catalyst is preferably carried out at a space hourly speed in weight (HSV) in the range of about 0.1 to about 300 hr "1 WHSV, more preferably in the range of about 10 a about 300 hr "1 WHSV, and most preferably in the range of about 20 to about 30 hr" 1 WHSV.The pressure can vary from less than atmospheric pressure to 100 psig or more.The cracking or disintegration process it can be carried out in any disintegration vessel such as a fluid catalytic disintegrator, a moving bed disintegrator, a fluidized bed, or a transfer line.The hydrocarbon flow can be co-current or countercurrent.The catalyst with coke it can be regenerated and returned to the process vessel, or the process can be run as a batch process.The process of the invention can also be carried out in a fixed bed disintegrator and catalyst. It can be regenerated in if you. As used herein, "catalytic disintegration conditions" include a reaction carried out in any of the above systems. Example 1 - Preparation of Aluminum Phosphate In a 100 ml round bottom flask, 15.00 g of Al (N03) 3"5H20 were dissolved in about 20 ml of water. In the aluminum nitrate solution, 4.60 g of NH4H2P04 was dissolved. To the mechanically stirred solution, concentrated NH4OH (28-30% by weight) was added dropwise (0.1 ml / min) until a gel was formed, pH 6-7. The stirred gel is connected to a flask containing 20 ml of concentrated NH40H and stirring was maintained overnight, the NH4OH flask being heated to 50 ° C. This apparatus allows the gel to age under an ammonia atmosphere. dried at 70 ° C in a vacuum oven, then calcined at 500 ° C for one hour in air Example 2 - Physical Mix of Phosphorus Treated Zeolite with Dry A1P04 To a slurry of 5.0 g of zeolite ZSM-5, with the Minimum amount of water needed to form a slurry, 0.46 g of NH4H2P04 was added.The treated zeolite was dried at 70"C in a vacuum oven. To the dried zeolite, 0.50 g of AlP04 was added, with barely enough water to make a slurry. The mixture was dried in a vacuum oven at 70 ° C and 85 kPa. The dry mix is mixed well with 13.27 ml of Ludox AS-40, then dried at 70 * C at about 85 kPa. The catalyst was subjected to ion exchange with NH4 three times at 80 * C, with 60 ml of a 5% by weight aqueous solution of NH4C1 and washed until chloride-free by the AgN03 test. The dry catalyst was formed into beads under 12 tons of pressure, and shredded to a 60-100 mesh size. The resulting catalyst composition was 1% P / 4% AlPO4 / 40% ZSM-5/55% SiO2. The same procedure was used with suitable adjustment of proportions, to produce a series of catalysts with the composition 0-1% P / 0-8% AlPO4 / 40% zeolite / 51-60% SiO2. Example 3 - Zeolite Treated with Phosphorus with A1P04 in Wet Gel A solution of 18.5 g of NH4H2P04 in 120 ml of water was used to wet 200 g of NH4ZSM-5 until incipient humidity. The sample was dried under vacuum at 70 ° C and then calcined at 500 ° C for one hour. The calcined solid was physically mixed to be uniform, with A1P04, produced by dissolving 58.4 g of A1 (N03) 3 »9H20 and 17.9 g of NH4H2P04 in 155 g of H20, followed by the addition of 20-24 g of concentrated NH4OH while the The mixture is physically mixed vigorously at a final pH in the range of 7-9. The mixture was placed in a closed vessel over the NH4OH solution at 40 * C overnight to age the gel, then dried. The dry mixture was physically mixed with 580 g of Ludox AS-40 (a silica sol) and dried. The dry catalyst was exchanged with 5% aqueous solution of NH4C1 (w / w) three times and washed until free of chloride by AgN03 tests. The solid is dried, then calcined at 500 ° C for 6 hours, followed by further exchange with NH 4 Cl (3 times) until chloride free, and the catalyst dried. The presence of aluminum phosphate formation in the catalyst was confirmed by MAS-NMR spectroscopy. Example 4 - Formation of A1P04 I Yes tu A zeolite catalyst with in formation of aluminum phosphate was prepared by physically mixing acetoacetonate of fine ground aluminum with ZSM-5 (either with or without alumina) in free silica sol of sodium Ludox AS-40. The vigorously stirred physical mixture was dried on a hot plate. The resulting mass was further dried under vacuum at 80 * C. The vacuum dried product was heated under nitrogen flow at 150 ° C and maintained for one hour, then heated to 500 ° C and maintained for one hour. The heating was continued with air flow for two hours to eliminate any residual carbon by combustion. The calcined catalyst was treated with NH4H2P04 solution to obtain the desired phosphorus content. The formation of aluminum phosphate in the catalyst with alumina was confirmed by MAS-NMR spectroscopy. Example 5 - Disintegration of N-Hexane with Wet Gel Catalysts and Dry Physical Mixture Catalysts prepared as in Examples 2 (dry) and 3 (wet gel) were used in a model system to disintegrate undiluted n-hexane. A series of runs was conducted in a small bench reactor over the n-hexane model compound. Prior to the decay tests, the catalyst was subjected to water vapor with 100% steam at 704 * C and an atmosphere for 16 hours in order to age the catalyst. A first run was conducted at 650 ° C, 31 hr "1 WHSV on a fixed bed of 0.6 g of the selected zeolite catalyst.The effluent stream was analyzed by line gas chromatography.A column having a length of 60 m, packed with fused silica, was used for the analysis The gas chromatograph used was a Hewlett-Packard model 5880 double-flame ionization (FID) detection device. The results are shown in Table 1 below: Table 1 Example 6 - Disintegration with Water Steam Co-Feeding A run conducted as in Example 5, using the catalyst prepared as in Example 3. In this test run, the weight ratio of water vapor to hydrocarbon was 0.33. . The results are shown in Table 2 below: Table 2 Example 7 - Disintegration of Butadiene-Hexane Model Compounds A run was conducted as in Example 5, with butadiene / hexane diluted 16/1 with steam (6/1) and nitrogen (10/1) at 680 * C, 5 hr "1 WHSV, and the results are shown in Table 3: Table 3 Example 8 - Comparative Examples Showing Synergy of Phosphorus Treatment and Addition of A1P04 ZSM-5 Ammonia treated with NH4H2P04 was physically mixed with fresh A1P04, prepared as in Example 1, and combined with Ludox AS-40 as in Example 3 , to produce a series of catalyst samples having different phosphorus charges and amounts of A1P04. The catalysts were tested as in Example 5, with application of steam for 8 hours at 700 ° C, run at 650 ° C, 4 hr "1 WHSV, and the results are indicated in Table 4 below, showing the composition of the catalyst giving the percentage of P, A1P04, and zeolite, the remainder being silica The table reports the conversion of n-hexane in weight percentage.

Example 9 - A1P04 Catalysts Formed In Situ A series of runs with catalysts prepared according to Example 4, with n-hexane at 650"C, 2 hr" 1 WHSV was carried out as in Example 5. The results are reported in Table 5 for catalysts without alumina, 40% ZSM-5 and 60% silica, and 40% alumina, 40% ZSM-5 and 56% silica. The table reports the conversion of n-hexane in weight percentage. Table 5 Example 10 - Disintegration at Lower Temperature A series of catalysts was prepared by first charging 2% P onto ZSM-5 ammonia at a Si / Al ratio of 27, impregnating the zeolite with aqueous NH 4 H 2 P0 4, followed by calcination at 500 ° C for one hour. , as in Example 2. The divided product was mixed with wet gel prepared as in Example 1 to produce batches containing 10%, 15% and 20% of A1P04, based on the zeolite. The mixture was aged over NH4OH solution in a closed vessel at 40 ° C overnight The solid was then physically mixed with Ludox AS-40 and dried The zeolite content in the mixture was 40% on a dry weight The catalyst was exchanged three times against 5% aqueous NH4C1 and washed until free of chloride, by the AgN03 test.The catalysts were subjected to water vapor at 700 * C for 16 hours, and tested against n- hexane as in Example 5 at 450 ° C, 30 hr "1 WHSV without diluent. The results are reported in Table 6. Table 6

Claims (24)

1. CLAIMS 1. A process for improving the catalytic activity of small and medium pore acid zeolite, comprising the steps of treating at least one small or medium pore acid zeolite with 0.5 to 10% by weight of a phosphorus compound to form a zeolite treated with phosphorus, and combining the phosphorus treated zeolite with 1 to 50% by weight of A1P04, based on the weight of the zeolite.
2. 2. The process of claim 1, wherein the phosphorus compound is selected from the group consisting of ammonium acid phosphate, ammonium dihydrogen phosphate, phosphoric acid or an acid salt thereof, polyphosphoric acid or an acid salt thereof, an organic phosphite, and an organophosphine.
3. 3. The process of claim 1, wherein the zeolite to be treated with phosphorus comprises a structure type selected from the group consisting of MFI, MEL, MTW, EUO, MTT, FER, MFS, TON, CHA, ERI, MAZ, OFF , RHO, HEV, KFI, LEV and LTA. The process of claim 1, wherein the zeolite to be treated with phosphorus is selected from the group consisting of ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38 , ZSM-48, ZSM-50, ZSM-57, MCM-22, silicalite-1, silicalite-2, ZK-
4. 4, SAPO-34, SAPO-35, ZK-14, SAPO-42, ZK-21, ZK -22, ZK-5, ZK-20, zeolite A, erionite, chabazite, zeolite T, gmelinite, ALPO-17, clinopti-lolita, mazzite, offretite, heulandite and rho zeolite.
5. 5. The process of claim 1, wherein the zeolite to be treated with phosphorus has a ring structure of ten members.
6. 6. The process of claim 1, wherein the zeolite to be treated with phosphorus has an eight-membered ring structure.
7. The process of claim 1, wherein the zeolite to be treated with phosphorus is selected from the types of structures consisting of MFI, MEL, MTW, EUO, MTT, FER, MFS and TON.
8. The process of claim 1, wherein the zeolite to be treated with phosphorus is selected from the structural types consisting of CHA, ERI, MAZ, OFF, RHO, HEV, KFI, LEV and LTA.
9. The process of claim 1, wherein the zeolite to be treated with phosphorus is selected from the group consisting of ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38. , ZSM-48, ZSM-50, ZSM-57, MCM-22, silicalite-1, and silicalite-2.
10. The process of claim 1, wherein the zeolite to be treated with phosphorus is selected from the group consisting of ZK-4, SAPO-34, SAPO-35, ZK-14, SAPO-42, ZK-21, ZK-22 , ZK-5, ZK-20, zeolite A, erionite, chabazite, zeolite T, gmelini-ta, ALPO-17, clinoptilolite, mazzite, offretite, heulandite and rho zeolite.
11. 11. The process of claim 4, wherein the zeolite to be treated with phosphorus is ZSM-5.
12. The process of claim 1, further comprising the step of mixing the phosphorus treated zeolite having A1P04 with a binder material, in an amount of 5-60% by weight of zeolite and 40-95% by weight of binder material.
13. The process of claim 12, wherein the binder material is selected from the group consisting of kaolin, silica, alumina, and mixed oxides.
14. The process of claim 12, wherein the phosphorus compound is used in an amount of 1% by weight and the A1P04 in an amount of 4% by weight, based on the weight of the zeolite, and the final product has the composition of about 40% by weight of zeolite / 55% by weight of SiO2.
15. 15. A process of claim 1, wherein the AlP04 is selected from the group consisting of a freshly prepared moist gel, a dry gel and a dried calcined gel.
16. 16. A process of claim 1, wherein the process comprises a first step of treating the zeolite with a phosphorus compound, calcining the zeolite treated with phosphorus, and combining the calcined zeolite, treated with phosphorus with AlP04.
17. The process of claim 1, wherein the combined phosphorus zeolite and A1P04 are subjected to water vapor.
18. 18. A composition of material prepared according to the process of any of the preceding claims.
19. 19. A process to disintegrate a hydrocarbon, which comprises contacting a hydrocarbon feedstock under catalytic disintegration conditions with a catalyst comprising the composition of claim 18.
20. 20. A process according to claim 19, wherein the feedstock is selected from the group that it consists of butane, gasoline, gasoils, Fischer-Tropsch liquids, refined, natural field gasolines, petroleum, paraffins, vacuum gasoils, olefins, diolefins, butenes, butadienes, naphtas disintegrated with steam, catalytic naphtha disintegrated, naphtha coker, light virgin naphtha, light catalytic naphtha, non-hydrogenated C4 to C6 compounds of normal water vapor disintegrating effluent, vacuum residues, and effluent from a catalytic cracker.
21. 21. A process according to claim 19, wherein the feedstock is selected from the group consisting of light virgin naphthas, light catalytic naphtha, coker naphthas, non-hydrogenated C4 through C6 compounds of normal water vapor disintegrator effluent , and effluent from a catalytic disintegrator.
22. 22. A process according to claim 19, wherein the catalyst is added to the catalyst bed of a fluidized catalytic disintegrator in an amount sufficient to improve the production of propylene or butylene.
23. 23. A process according to claim 19, wherein the feed comprises naphtha.
24. 24. A process according to claim 19, wherein the naphtha is selected from the group consisting of saturated naphthas saturated, catalytically disintegrated naphthas, coker naphthas, and naphtas disintegrated with steam.