Methane Dehydroaromatization on Mo/HMCM-22 Catalysts: Effect of SiO2/Al2O3 Ratio of HMCM-22 Zeolite Supports

Abstract

HMCM-22 zeolite with variable SiO2/Al2O3 ratios has been successfully synthesized and used as support of molybdenum based catalyst in methane dehydroaromatization. Effect of SiO2/Al2O3 ratio on the catalytic performance of Mo/HMCM-22 catalysts was studied, and results show that methane conversion and benzene selectivity increase with the decrease of SiO2/Al2O3 ratio, and reach maximum on Mo/HMCM-22 catalyst with SiO2/Al2O3 ratio of 25. Further increasing SiO2/Al2O3 ratio results a decrease of activity and benzene selectivity. Al-27 MAS NMR spectroscopy and NH3-TPD techniques were applied to characterize the structure-property relationship of the catalyst. The catalytic performance of Mo/HMCM-22 catalysts in methane dehydroaromatization has been correlated with the Bronsted acidity of HMCM-22 zeolite supports, which may promote not only the methane activation on the Mo carbide sites of Mo/HMCM-22 catalysts, but also further oligomerization of the CHx surface species towards aromatics products in the reaction.