Influence of the acidity modification on the reactions of toluene and ethyl benzene disproportionation.Effect of Lewis acidic InO~+ species introduced into Y zeolite

摘要

Dealuminated in solid-state Y zeolite-modified with InO~+ by the method of reductive solid-state ion exchange (RSSIE) followed by oxidation have been studied in the reactions of toluene and ethyl benzene disproportionation.The role of the as-created electron acceptor Lewis sites has been investigated in the above Broensted-mediated catalytic reactions.These cationic centers of well-defined chemical nature are stabilized in desired amount without formation of mesopores in the zeolite in contrast to the Al-connected Lewis sites created upon hydrothermal treatment of Y zeolites.Thus,by eliminating the structural factor,an examination of the effect of the Lewis acidity on the catalytic performance has been undertaken.Contribution of the InO~+ cationic sites to the enhanced alkyl transfer,dealkylation and catalysts aging upon toluene and ethyl benzene conversion is suggested.It is assumed that they initiate themselves,or by the enhancement of the strength of the neighboring protons,a strong hydride abstraction resulting in highly accelerated formation of diphenylalkane reaction intermediates.This effect is more strongly pronounced with the increasing amount of incorporated indium.The changes in the inner volume of the zeolite caused by the presence of InO~+ cationic species can be considered negligible with respect to the catalytic behavior,compared to the effect of the acidity modification.