Novel Ce-doped MnOx catalysts for highly efficient catalysis of toluene oxidation at low temperature
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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