Investigation of Methane Oxidation Reactions Over a Dual‐Bed Catalyst System using ¹⁸O Labelled DRIFTS coupling

Abstract

Low loading Pd-supported (0.2 wt % Pd) Y-stabilized zirconia (YSZ) and LaMnO₃ (LM) perovskite were associated to study the partial oxidation of methane using labelled ¹⁸ O₂ in the gas phase. Synthesis gas production was demonstrated to occur through an indirect reaction in which oxygen is first consumed in the total methane combustion. A Mars-van Krevelen mechanism was observed over Pd/YSZ at 425 °C to yield C¹⁶ O₂ and C¹⁶ O. A significant enhancement of the Pd/YSZ catalyst activity was achieved by the association of LM-Pd/YSZ in a dual catalyst bed, resulting in a significant increase of the oxidation rate. Vibration bands of adsorbed formate species, assumed to be intermediates to the gas production, were observed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) coupling experiments. It was proposed that LM enables the generation of highly active singlet O₂ , which is activated on the YSZ oxygen vacancies to assist a rapid recovery of surface PdO and increase formate decomposition into CO and H₂ in Pd-supported catalyst.