Influence of the properties of zeolite BEA on its performance in the nitration of toluene and nitrotoluene

The nitration of toluene and 2-nitrotoluene was investigated using different batches of zeolite BEA. In the nitration of toluene, notable differences in the product composition were obtained depending on the batch of BEA used. In the nitration of 2-nitrotoluene, all the catalysts displayed a good selectivity, but different conversions. Steaming improved the performance of the catalysts, but strong dealumination with oxalic acid had a negative effect. The positive effect of steaming was attributed to the enhanced transport of the reaction products out of the pores. Lewis acidity did not seem to play a role in the nitration reaction. A high concentration of Bronsted sites was detrimental, because it slowed down the diffusion of the products, but a small concentration of Bronsted sites was required to catalyze the heterogeneous reaction. (C) 2004 Elsevier Inc. All rights reserved.