Experimental and Theoretical Investigation of the Catalytic Activities of Different Zeolites for the Nitration of Toluene

Zeolites are used in the field of toluene nitrification reactions, but their intrinsic mechanism is not well explained. In this work, three typical zeolites including HZSM-5, HY, and Hβ are selected as catalysts and used for the nitration of toluene and typical monosubstituted benzenes with NO2, and it explores the intrinsic influences on the nitrification of toluene on various zeolites through experimental and theoretical methods. The acidic properties and pore structures of three different zeolites were investigated through appropriate characterization techniques. Hβ zeolite exhibited the highest catalytic performance among the three zeolites, attributable to its unique pore structure and acidic properties. The theoretical analysis of various zeolites indicates that the Hβ zeolite can effectively reduce the activation energy barrier, thereby significantly enhancing the transfer nitration performance. The theoretical calculations also suggest that the para-nitration product is more readily formed within the pores of Hβ zeolite, resulting in high para-selectivity. This study provides a theoretical basis for the selective catalysis of aromatics on zeolites.