Room temperature synthesis of diphenylmethane over novel mesoporous Lewis acid catalysts

Abstract

Highly selective synthesis of diphenylmethane (DPM) was carried out by Friedal–Crafts benzylation of benzene using benzyl chloride (BC) as alkylating agent in the presence of a flow of nitrogen under liquid phase reaction conditions over novel mesoporous SO 4 2−/Al-MCM-41 catalysts with different Si/Al ratios. For these reactions, the influences of various reaction parameters, such as different catalysts, reaction temperature, time, mmol ratios of reactants and recyclability are discussed. With increasing the Si/Al ratios of SO 4 2−/Al-MCM-41 catalysts from 21 to 83, the conversion of BC and selectivity of DPM decreased because the number of Lewis acid sites in SO 4 2−/Al-MCM-41 catalysts are found to decrease almost linearly with increasing ratios of Si/Al. Further the catalytic results were compared with those obtained by using 0.8N sulfuric acid, different Si/Al ratios of Al-MCM-41, HY, Hβ, HM and H-ZSM-5 zeolites. From the comparison of the results, SO 4 2−/Al-MCM-41(21) is found to be a highly active and recyclable heterogeneous catalyst for the highly selective synthesis of DPM. Thus, the selectivity of DPM in SO 4 2−/Al-MCM-41(21) is higher than that in other SO 4 2−/Al-MCM-41 (Si/Al = 42 and 83), Al-MCM-41 (Si/Al = 21, 42 and 83), HY, Hβ, HM and H-ZSM-5.