Selective Oxidation of Toluene with Hydrogen Peroxide Catalyzed by V-Mo-based Catalyst

摘要

The selective catalytic oxidation of toluene with hydrogen peroxide over V-Mo-based catalysts under mild conditions was studied. The promotion effect of Mo on the catalysts was studied with V/Al_2O_3 and Mo/Al_2O_3 as reference samples. The catalysts were characterized by XRD, TPR, and XPS techniques. The results show that the addition of Mo to V/Al_2O_3 may change the distribution of V species on Al_2O_3 surface. Over V-Mo/Al_2O_3 catalyst, highly dispersed amorphous V species facilitates benzaldehyde formation, and crystalline V_2O_5 species increases the conversion of toluene but decreases the selectivity to benzaldehyde, while AlVMoO_7, species favors both the conversion of toluene and the formation of cresols. The yield of benzaldehyde depends remarkably on the surface O/Al and Mo/V atomic ratios, and gets to a maximum value of 13. 2% with a selectivity of 79. 5% at an O/Al atomic ratio of 3. 0 and Mo/V atomic ratio of 0. 7.