Investigating the differences of active oxygen species and carbonate species on the surface of CeM (M = Mn and Zr)O catalysts prepared by the aerosol method during CO oxidation using TPR-DRIFTS-MS.

Surface oxygen species and carbonate species play an important role in CO oxidation. However, their essential relationsh with CO oxidation activity remains unclear. In this paper, CeM (M = Mn and Zr)O catalysts are selected as the research target and TPR-DRIFTS-MS is used to investigate the changes of oxygen species and carbonate species on the catalyst surface. The CeMnO catalyst has the best CO conversion (145 °C) and CO selectivity (99%). DRIFTS-MS results show that MO plays a key role on the catalyst surface and can react with CO at low temperatures. Importantly, the high content of MO is conducive to the formation of monodentate carbonate (M-O-CO) (M-O-CO decomposes at 50 °C). As the temperature increases, CeO and M-O-Ce also react with CO and produce M-O-Ce (oxygen vacancies). CO can combine with O adsorbed on the M-O-Ce (M-O) to form bidentate carbonate (M-O-CO). The decomposition temperature of M-O-CO is much higher than that of M-O-CO, and its existence is the decisive step of CO oxidation. The above results provide a new way to regulate the surface oxygen species and carbonate species of Ce based catalysts in the later stages.