Benzylation of benzene by benzyl chloride over Fe-modified ZSM-5 and H-β zeolites and Fe₂O₃ or FeCl₃ deposited on micro-, meso-and macro-porous supports

Abstract

A number of Fe-containing solid catalysts, such as Fe-modified ZSM-5 type zeolites (Fe₂O₃/H-ZSM-5, SO₄^2-/Fe₂O₃/H-ZSM-5, H-FeMFI and H-FeAlMFI), Fe-modified H-β zeolites (Fe₂O₃/H-β and SO₄^2-/Fe₂O₃/H-β), Fe₂O₃ supported on meso-porous Si-MCM-41, silica gel or macro-porous silica-alumina commercial catalyst carrier (SA-5205), and FeCl₃ impregnated on 13X zeolite, Si-MCM-41, silica gel or commercial clays--montmorillonite K10 (Mont K10) or kaolin, have been compared for their performance in the benzylation of benzene by benzyl chloride (80°C). Among these catalysts, the Fe₂O₃/H-β (or H-ZSM-5) and FeCl₃/Mont K10 (or Si-MCM-41) are found to be highly promising ones for the benzylation, even in the presence of moisture. These catalysts can also be reused in the reaction but with reduced activity. No direct relationship is observed between the acidity (measured in terms of ammonia chemisorbed at 50 or 200°C) and the benzylation activity of the catalysts. The benzylation activity is controlled mainly by the redox properties of the catalyst. The selectivity for diphenyl methane in the benzylation was found to vary from catalyst to catalyst.