Novel Ce-doped MnOx catalysts for highly efficient catalysis of toluene oxidation at low temperature
. WANG Pei-fen1, AN Xiao-wei1, MA Xu-li1, GUAN Guo-qing2, HAO Xiao-gang3
1. College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China; 2. Energy Conversion Engineering Laboratory, Institute of Regional Innovation, Hirosaki University, Hirosaki 036-8561, Japan; 3. Department of Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Abstract：Novel Ce-doped MnOx bimetallic catalyst was successfully prepared by co-oxidation-precipitation method, and the influence of synergy between Ce and Mn was explored for catalytic toluene oxidation at low temperature. Characterizations by SEM、XRD、N2 adsorption-desorption、XPS、EPR、H2-TPR, and in situ DRIFTS were performed for the prepared catalysts. It is found that the catalysts with an optimum Ce/Mn molar ratios of 1:3 had a highest performance with T50 of 215℃ and T90 of 233℃, good durability and water resistance for the toluene oxidation. Meanwhile, the results confirmed that the introduction of Ce was beneficial to adjust the morphology of CeMn3Ox catalyst with the formation of coral-structure, leading to the increase in the number of interfaces between crystalline-amorphous, which caused more defects and oxygen vacancies in the bulk of catalyst, promoting the conversion of Olatt↔ Osur↔Oads and enhancing the reducibility. Finally, in situ DRIFTS spectra verified that toluene oxidation followed two reaction pathways under air conditions,Ⅰ:adsorption→benzyl alcohol→benzaldehyde→benzoate→phenol→ benzene ring C=C breakage→ CO2 and H2O,Ⅱ: adsorption → benzene ring C=C cleavage breakage →Maleic anhydride→ CO2 and H2O, in which the C=C breakage of the aromatic ring was considered as a rate-controlled step.
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