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Transformation of some light mono- and dialkylbenzenes on H-ZSM-5

Journal Article · · Journal of Catalysis; (United States)
 [1]
  1. Central Research Institute for Chemistry, Budapest (Hungary)

The catalytic alkylation of toluene with small olefins is of great industrial importance. Medium pore-size zeolites such as ZSM-5 are active in alkylation and also effect the transformation of alkyl aromatic hydrocarbons, favoring the formation of the para-substituted derivatives. In zeolites, where intracrystalline pore dimensions approach molecular dimensions, the mass transport proceeds in the regime of the so-called [open quotes]configurational diffusion.[close quotes] In ZSM-5 the diffusivities of aromatic molecules decreases systematically with the increasing effective minimum dimension of the molecules. Shape selectivity is governed by the diffusivity of the aromatic molecules inside the zeolite crystals, consequently it decreases with decreasing crystal size and vice versa. In ethylation of toluene on unmodified microcrystalline H-ZSM-5, a complex product mixture containing benzene, xylenes, ethylbenzene, traces of trimethyl- and diethylbenzenes was obtained. In this work the expected side reactions of toluene ethylation, as transformations of toluene (T), p-ethyltoluene (PET), ethylbenzene (EB), and xylenes (X) were studied on the same H-ZSM-5 under the conditions of ethylation in order to shed some light on the mechanism directing the formation of the product mixture.

OSTI ID:
7045971
Journal Information:
Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 145:2; ISSN 0021-9517; ISSN JCTLA5
Country of Publication:
United States
Language:
English