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(12) Patent Application Publication (10) Pub. No.: US 2005/0070422 A1 Chen Et Al

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(12) Patent Application Publication (10) Pub. No.: US 2005/0070422 A1 Chen Et Al US 2005.0070422A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2005/0070422 A1 Chen et al. (43) Pub. Date: Mar. 31, 2005 (54) MULTICOMPONENT CATALYST AND ITS Publication Classification USE IN CATALYTIC CRACKING (51) Int. Cl." ........................... C10G 11/00; C10G 11/05 (76) Inventors: Tan-Jen Chen, Kingwood, TX (US); (52) U.S. Cl. ....................... 502/64; 208/120.01; 208/113 John Scott Buchanan, Lambertville, NJ (US); Brian Erik Henry, Baton Rouge, LA (US); Paul F. (57) ABSTRACT Keusenkothen, Houston, TX (US); A multi component catalyst and catalytic cracking proceSS Philip A. Ruziska, Kingwood, TX for Selectively producing Colefins. The catalyst comprises (US); David L. Stern, Annandale, NJ a first molecular Sieve having an intermediate pore size, a (US) Second molecular Sieve and, optionally a third molecular Correspondence Address: Sieve having a large pore size. At least one of the channels EXXONMOBIL CHEMICAL COMPANY of the Second molecular Sieve has a pore size indeX that is 5200 BAY WAY DRIVE less than the pore size index of at least one channel of the P.O. BOX 21.49 first molecular Sieve. The proceSS is carried out by contact BAYTOWN, TX 77522-2149 (US) ing a feedstock containing hydrocarbons having at least 5 carbon atoms is contacted, under catalytic cracking condi (21) Appl. No.: 10/671,080 tions, with the multi component catalyst. The catalyst finds application in the cracking of naphtha and heavy hydrocar (22) Filed: Sep. 25, 2003 bon feedstocks. US 2005/0070422 A1 Mar. 31, 2005 MULTICOMPONENT CATALYST AND ITS USE IN catalytic cracking of a hydrocarbons, Such as naphtha, to CATALYTIC CRACKING Selectively produce propylene or as an additive catalyst in combination with a large pore molecular Sieve catalyst in the FIELD OF THE INVENTION catalytic cracking of heavier hydrocarbon feedstocks. The 0001. The present invention relates to catalytic cracking catalyst comprises a first molecular Sieve having an inter of hydrocarbon feedstocks to enhance the yield of propy mediate pore size and a Second molecular Sieve having a lene. pore size index of at least one of its major channels that is BACKGROUND TO THE INVENTION less than the pore size index of at least one of the major channels of the first molecular sieve. When used in the 0002 The need for low emissions has created an catalytic cracking of heavier hydrocarbon feedstocks, the increased demand for light olefins for use in alkylation, catalyst comprising the first and Second molecular Sieves is oligomerization, and MTBE and ETBE synthesis processes. used in combination with a third molecular Sieve having a In addition, a low cost Supply of light olefins, particularly large pore size. propylene, continues to be in demand as feedstock for polypropylene production. 0008. In another embodiment, the present invention pro vides a process for catalytically cracking a hydrocarbon 0.003 Light olefins, such as ethylene and propylene, can feedstock to selectively produce Colefins. The process is be produced by thermally cracking naphtha feedstocks con carried out by contacting a hydrocarbon feedstock contain taining paraffinic and isoparaffinic compounds, naphthenes ing hydrocarbons having at least 5 carbon atoms under and aromatics to produce light olefins. The thermal cracking catalytic cracking conditions and in the presence of the of naphtha is carried out by exposing naphtha and Steam to relatively high temperatures in the tubular coils of a fired catalyst described above. heater. A problem associated with this technique is that the 0009. In one preferred embodiment, the feedstock used in proceSS is energy intensive, not very Selective, produces the proceSS comprises a naphtha having a boiling range of coke, and releases Significant amounts of carbon dioxide about 25 C. to about 225 C. into the air. 0010. In a further preferred embodiment, the feedstock 0004 Another technique for producing light olefins used in the proceSS comprises hydrocarbon mixture having involves the catalytic cracking of hydrocarbons, Such as an initial boiling point of at least 200 C. and the catalyst naphtha. In the catalytic cracking of naphtha, the process is comprises first, Second, and third molecular Sieves. carried out by contacting a naphtha-containing feed with a catalyst usually comprised of one or more crystalline DETAILED DESCRIPTION OF THE microporous molecular Sieves to Selectively convert the feed INVENTION into an olefin-containing mixture. Although various naphtha catalytic cracking processes have been proposed in the past, 0011 Catalyst many of the processes do not produce commercially impor tant light olefins, e.g., propylene, with Sufficient Selectivity 0012 First and Second Molecular Sieves or yield. Also, the processes can produce undesirable 0013 The first molecular sieve used in the catalyst is an amounts of methane and aromatics as unwanted byproducts. intermediate pore size molecular sieve. Intermediate pore In contrast, a practical and economic naphtha catalytic Size molecular Sieves have a pore size from about 5 A to cracking process should Selectively produce increased about 7 A and include, for example, ITH, MFI, MEL, MFS amounts of light olefins, e.g., propylene, while producing MTW, and MWW structure types (IUPAC Commission of minimal amounts of methane and aromatics. Zeolite Nomenclature). These molecular sieves, as well as 0005 Fluid catalytic cracking (FCC) is routinely used to many other molecular Sieves, are described in Atlas of convert heavy hydrocarbon feedstocks to lighter products, Zeolite Framework Types, eds. Ch. Baerlocher, W. H. Meier, Such as gasoline and distillate range fractions. Conventional and D. H. Olson, Elsevier, Fifth Edition, 2001 (hereinafter processes for catalytic cracking of heavy hydrocarbon feed referred to “the Atlas”), which is hereby incorporated by Stocks to gasoline and distillate fractions typically use a reference. Examples of preferred first molecular Sieves catalyst containing a large pore molecular Sieve, Such as include ZSM-5, ZSM-11, ZSM-12, ZSM-57, ITO-13, and Zeolite Y, as the primary cracking component and, option MCM-22. ally, an intermediate pore size molecular Sieve, Such as ZSM-5. While FCC is an efficient process for converting 0014. The preferred second molecular sieves include heavier feed to lighter products, many times the proceSS AEL, AFO, CHA, TON, FER, MTT, and MWW structure makes less than desirable amounts of light olefins, e.g., types (IUPAC Commission of Zeolite Nomenclature). propylene. Examples of preferred Second molecular Sieves include chabazite, ECR-42, ZSM-22, ZSM-35, ZSM-23, MCM-22, 0006 The present invention provides a catalyst and pro MCM-49, SAPO-11, SAPO-34, and SAPO-41. Generally, ceSS for the catalytic cracking of hydrocarbon feedstocks, the Second molecular Sieve will have an intermediate pore e.g. naphtha and heavier hydrocarbon feedstocks, which is Size or Small pore size, i.e., pore size from 3 A to about 5 A. effective in producing enhanced yields of propylene, as Usually, the Second molecular Sieve will have a pore diam compared with known processes used to crack hydrocar eter greater than about 3.5A to admit Cs molecules into the bons. channels and allow C olefins to diffuse out of the channels. SUMMARY OF THE INVENTION 0015. At least one of the channels of the second molecu 0007. In accordance with the present invention, there is lar Sieve has a pore size index that is less than the pore size provided a catalyst finding particular application in the index of at least one channel of the first molecular sieve. The US 2005/0070422 A1 Mar. 31, 2005 Second molecular Sieve will have a structure type that is different from the structure type of the first molecular sieve. TABLE I 0016. As used herein, the expression “channel” or “chan Second Molecular nels' with respect to the first and Second molecular Sieves, First Molecular Sieve Sieve means the channels formed by the crystalline network of the Structure Structure molecular Sieve. These channels allow adsorption of hydro Type? Type? carbons into the molecular sieve. The expression “channel” Exemplary Exemplary or channels does not include other Spaces formed by the Molecular Pore Size Molecular Pore Size crystalline network of the molecular Sieve Spaces that do not Catalyst Sieve Index Sieve Index allow the adsorption of hydrocarbons. A. MFI/ZSM-5 28.05 and AELSAPO- 26.00 29.68 11 0.017. The expression “pore size index”, as used herein, B MEL/ZSM- 28.62 TON/ZSM- 26.22 means the product of the dimensions (in Angstrom units) of 11 22 C MTW/ZSM- 33.6 AFOfSAPO- 30.10 the two major axes of the pores of the molecular Sieve. 12 41 D MWWMCM- 22.OO and FER/ZSM- 22.68 and 0.018. The first and second molecular sieves present in the 22 20.91 35 16.8 catalyst include molecular Sieves having one dimensional, E MFS/ZSM- 27.54 and MWWMCM- 22.OO and non-interconnecting channels, molecular Sieves having two 57 15.84 22 20.91 F MEL/ZSM- 28.62 AEL 26.00 dimensional, non-interconnecting channels, and molecular 11 ECR-42 Sieves having three-dimensional, interconnecting channels. G MFI/ZSM-5 28.05 and CHAISAPO- 14.44 29.68 34 0019. The amount of first molecular sieve and second H MTW/ZSM- 33.6 CHAfChabazite 14.44 molecular Sieve present in the catalyst will vary over a wide 12 range and thus there are no Set ranges. Usually, the relative I MFS/ZSM- 27.54 and MWWMC- 22.00 and 57 15.84 49 20.91 weight ratio of first molecular Sieve to Second molecular J ITH/ITO- 26.40, CHAISAPO- 14.44 sieve in the catalyst is between about 0.1:10 to about 10:1. 13 28.5, and 34 Preferably, the relative weight ratio of first molecular sieve 19.6 to second molecular sieve will be from about 0.1 to about 10, and, more preferably, between about 0.3 to about 1.0 0024 Preferably, all of the channels of the second 0020.
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