Catalytic behaviors of chloromethane combustion over the metal-modified ZSM-5 zeolites with diverse SiO2/Al2O3 ratios

A series of M/ZSM-5 (M = Co, Fe, Ce, and Mn) catalysts with different molar ratios of SiO2/Al2O3 (30, 107) was prepared via a traditional wetness impregnation, and further characterized by XRD, BET, H-2-TPR, NH3-TPD, and XPS as well as activity test for the catalytic combustion of chloromethane. Characteristic structure of ZSM-5 is basically maintained even after impregnating the various metallic components. Catalytic activities achieving under an atmosphere of 1500 ppm CH3Cl, 10% O-2, and GHSV of 15,000 h(-1) of the investigated catalysts follow a trend of Co/ZSM-5-30, Ce/ZSM-5-30 >Co/ZSM-5-107, Ce/ZSM-5-107, Fe/ZSM-5-30, Mn/ZSM-5-30 >Mn/ZSM-5-107, Fe/ZSM-5-107>H-ZSM-5-30> H-ZSM-5-107. The binary Co/ZSM-5-30 and Ce/ZSM-5-30 show the satisfactory conversions of CH3Cl (87% and 95%) associated with a low yield of CO (9.6% and 16%) at 400 degrees C, owing to the excellent redox properties (determined by the chemical nature of the loaded metallic components) and strong acidic properties (modified by Al isomorphic substitution) of the as-prepared zeolitic catalysts. (C) 2014 Elsevier B.V. All rights reserved.