A comparative study of the catalytic nitration of toluene over bimetallic Ce-Mn modified H zeolite

Bimetallic cerium-manganese modified H beta zeolite sample (Ce/Mn-H beta) was prepared by ultrasonic assisted impregnation method and applied in nitration of toluene. The characterization results show that the active components (Ce and Mn) are successfully introduced into the framework of H beta zeolite. The catalyst shows excellent catalytic activity and reusability for the nitration of toluene, giving high para selectivity. Under optimized conditions, it gives 68.7% selectivity to para-nitrotoluene at 88.6% conversion over Ce/Mn-H beta in the presence of acetic anhydride (Ac2O). The theoretical calculations indicate that the Ce/Mn bimetallic active sites in modified H beta zeolite can easily activate the nitrification reagent (AcONO2), and the enhancement of para selectivity is owing to the steric hindrance of catalyst. Furthermore, the reaction mechanism was proposed by the combination of experimental results and theoretical calculations.