Insight into the surface reaction mechanism of toluene oxidation over a composite CeOx/La1-xCexMnO3 catalyst using DRIFTS

Abstract

In this work, La1-xCexMnO3 catalysts at different Ce concentrations were synthesized by the hydrothermal method, characterized and tested in the toluene oxidation reaction. The results show the formation of a composite catalyst of the CeOx/La1-xCexMnO3 type at Ce/Mn molar ratio > 0.3. In this composite catalyst, a synergistic effect promoting its catalytic activity was observed between CeOx and La1-xCexMnO3, which was enhanced by the existence of Ce3+ species in CeOX and promotion of Mn4+ species. A surface mechanism was proposed by in-situ DRIFTS measurements, which helped identify two different mechanisms by taking into account either the rich or poor surface active Olat present on the unsubstituted LaMnO3 catalyst and composite CeOx/La1-xCexMnO3 catalysts, respectively. According to the DRIFTS observations, the oxidation to benzoate species could be the most important step during the catalytic oxidation of toluene by the composite catalyst.