Shape selectivity of zeolite EU-1 in reactions of aromatic hydrocarbons

Abstract

The shape-selective properties of H-EU-1 in the isomerization of m-xylene and the methylation and disproportionation of toluene were studied and compared with those of H-ZSM-48. The presence of an one-dimensional ten-ring channel system together with deep side pockets off the channels in EU-1 leads to peculiar shape selectivity effects. The concentration of the para isomer in the isomerization products decreases in the order ZSM-48>EU-1>ZSM-5. The presence of large side pockets, in which bimolecular reactions such as xylene disproportionation can occur, leads to the following selectivity for isomerization versus disproportionation: ZSM-48>ZSM-5>EU-1. It is concluded that apart from the shape and size of the channel system, the presence or absence of pore intersections and cavities can also significantly affect the shape selectivity of medium-pore zeolites in catalytic reactions. It is suggested that shape selectivity effects in the isomerization of m-xylene can be used as diagnostic tools to reveal not only the size of the pores but also the presence or absence of cavities and the dimensionality of the pores in zeolites of unknown structure.