The critical role of MnCeOx molecular dispersion in harsh reaction conditions for VOC treatment

Abstract

Abstract The stability of catalysts perhaps is the most important issue for catalysis whatever fundamental or application. This study evaluates the stability of MnOx-CeO2 catalysts in the oxidation of ethyl acetate by comparing the performance of fresh catalysts with those treated under high-temperature hydrothermal conditions (750 ℃ and 5% steam for 12 h). Three different methods, namely redox-precipitation (RH), co-precipitation (CP), and impregnation (IP), were used to synthesize the catalysts and adjust the Mn-Ce dispersion. The activity difference between the fresh and treated catalysts decreased in the following order: RH-MnCe > CP-MnCe > IP-MnCe. Based on detailed characterizations and density functional theory calculations, the molecular dispersion of MnCeOx in RH-MnCe is key to ensuring the collapse resistance of Ce-doped Mn3O4, which yields the highest activity during ethyl acetate oxidation. This finding is supported by experiments conducted on RH-MnCe with different Mn/Ce ratios. Although the introduction of Ce can enhance the stability of Mn3O4, it must be carefully controlled at a moderate level to enable recycling between MnO2/Mn3O4.