Effect of mesoporosity on selective benzylation of aromatics with benzyl alcohol over mesoporous ZSM-5

The effect of mesoporosity on product distribution in benzylation of aromatics such as benzene, toluene, anisole and mesitylene with benzyl alcohol was investigated over various ZSM-5 catalysts with different degree of mesoporosity, which were prepared by microwave-induced assembly via ionic interaction between sulfonic acid-functionalized or non-functionalized ZSM-5 nanozeolites and counter cationic surfactant, and hydrothermal synthesis with or without sulfonic acid functionalization and surfactant. The product distribution of the aromatic benzylation was found to vary with the different mesoporosity. The selectivity of desired monobenzylated aromatic was increased from 19.8% to 75.5% with increasing mesopore volume from 0.11 to 0.75 cm(3)/g. Meso ZSM-5 (SO3H-CTAB)-MW with the highest external acid sites and mesopore volume showed better conversion as well as much higher selectivity of desired bulky monobenzylated aromatics than those of other catalysts, whereas microporous ZSM-5 mainly showed dibenzyl ether as major product due to diffusion limitation of bulky product. (C) 2012 Elsevier Inc. All rights reserved.