Abstract: There is provided a catalyst and a process for converting methanol or dimethyl ether to a product containing C.sub.2 to C.sub.4 olefins. The catalyst comprises a porous crystalline material having a Diffusion Parameter for 2,2-dimethylbutane of about 0.1-20 sec.sup.-1 when measured at a temperature of 120.degree. C. and a 2,2-dimethylbutane pressure of 60 torr (8 kPa). In addition, the catalyst is characterized by a hydrothermal stability such that, after steaming the catalyst at 1025.degree. C. for 45 minutes in 1 atmosphere steam, the catalyst exhibits a methanol conversion activity of at least 50% when contacted with methanol at a methanol partial pressure of 1 atmosphere, a temperature of 430.degree. C. and 0.5 WHSV. The porous crystalline material is preferably a medium-pore zeolite, particularly ZSM-5, which contains phosphorus and has been severely steamed at a temperature of at least 950.degree. C.

Abstract: There is provided a process for converting methanol and/or dimethyl ether to a product containing C.sub.2 to C.sub.4 olefins which comprises the step of contacting a feed which contains methanol and/or dimethyl ether with a catalyst comprising a porous crystalline material, said contacting step being conducted in the presence of an aromatic compound under conversion conditions including a temperature of 350.degree. C. to 480.degree. C. and a methanol partial pressure in excess of 10 psia (70 kPa), said porous crystalline material having a pore size greater than the critical diameter of the aromatic compound and the aromatic compound being capable of alkylation by the methanol and/or dimethyl ether under said conversion conditions.

Abstract: A process is described for isomerizing a feed which contains ethylbenzene and xylene, which process comprises the steps of:(a) contacting the feed under ethylbenzene conversion conditions with a particulate first catalyst component which comprises a molecular sieve having a constraint index of 1-12, the particles of said first catalyst component having a surface to volume ratio of about 80 to less than 200 inch.sup.-1 and the contacting step converting ethylbenzene in the feed to form an ethylbenzene-depleted product; and then(b) contacting the ethylbenzene-depleted product under xylene isomerization conditions with a second catalyst component.