Catalytic oxidation of toluene over Co3O4-CeO2 bimetal oxides derived from Ce-based MOF

Abstract

A series of Co–Ce oxide catalysts with different molar ratios were prepared by impregnation and pyrolysis using a Co-loaded Ce-based metal–organic framework as a precursor. Physicochemical properties of the catalysts were characterized by N2 adsorption–desorption measurements, X-ray diffraction, H2 temperature-programmed reduction, Raman analysis, X-ray photoelectron spectroscopy, transmission electron microscopy, thermal desorption-gas chromatography-mass spectrometry and scanning electron microscopy. Toluene was selected as a reference to evaluate catalytic performance. Results show that the catalyst prepared at a Co/(Ce+Co) molar ratio of 0.3 exhibits excellent catalytic activity in the catalytic oxidation of toluene. The temperature at 90 % conversion of toluene (T90) is 262 °C which is significantly lower than the catalyst prepared by the traditional preparation method. The specific surface area is not the main factor affecting the reaction. The high activity is due to the better low temperature reducibility, abundant lattice defects, more active oxygen species, higher surface Ce3+ species (oxygen vacancies). What's more, 30Co-Ce has superior stability at different conversion rates and tolerance in the presence of water vapor. The results stated above indicate that the surface properties of the Co-Ce catalysts significantly affected the toluene combustion reaction.