Benzylation of biphenyl with benzyl chloride over HY zeolites: A kinetic model for reaction and catalyst deactivation

Two dealuminated HY zeolites were employed as catalysts for the Friedel-Crafts reaction of biphenyl with benzyl chloride in a slurry batch reactor, with solvents cyclopentane, cyclohexane, and methylcyclohexane, at temperature from 50 to 100 degrees C. Mainly benzylbiphenyl isomers (M), but also appreciable quantities of dibenzyl derivatives (D) were obtained and determined. Within the monobenzylated fraction, a para-selectivity of 65-70% at 60% conversion was reached. Magnetic stirring was found to be adequate for a chemically controlled reaction kinetics. Kinetic models, including equations for the process itself and for the catalyst deactivation, and applied on the basis of optimization procedures, were used to correlate the results. The model of choice was able to interpret runs carried out at different doses of catalyst and different initial concentrations of the benzylating agent. A solvent effect on the kinetics was evidenced. Deactivated catalysts were regenerated for a few reaction-regeneration cycles.