Gas-phase nitration of toluene with zeolite beta

Abstract

Abstract The gas-phase nitration of toluene was studied over a solid-acid zeolite beta catalyst with two different nitrating agents, HNO 3 and N 2 O 4 , in a setup for continuous nitration. The selectivity of the reactions to 4-nitrotoluene was good, but the catalysts deactivated within a few hours. HNO 3 gave higher yields than N 2 O 4 , but both HNO 3 and N 2 O 4 required a temperature lower than 160 °C to obtain acceptable yields and less oxidation products. At higher temperatures, catalyst deactivation was accelerated and the yield of nitrotoluene decreased. Lowering the feed rate of toluene led to a slower deactivation of catalyst. The deactivation of the catalyst was caused by pore blocking due to liquid reaction products as well as coke formation. Unlike in liquid-phase nitration, dealumination did not play a role in the deactivation of the catalyst, which could be regenerated by calcination in air.