Ab initio quantum chemical study on the zeolite catalyzed transformations of para-xylene

Unimolecular 1.2-methyl shift reaction and disproportionation of para-xylen e is investigated by means of ah initio quantum chemical calculations. Isol ated gas-phase models are used to estimate the optimum volume of the reacti on complex. Space filling of the computed models is examined in zeolite Y, Beta and ZSM-5, It is suggested that the shape selectivity effect of zeolit e molecular sieves on the disporportionation reaction can be associated wit h the steric conditions of the intrinsic rearrangement of the reaction comp lex in the course of the chemical transformation. (C) 2001 Elsevier Science B.V. All rights reserved.