Elaborating the effects of oxygen species in Ag[dbnd]O, Mn[dbnd]O, Mn-O-Mn, and Ag-O-Mn on CO oxidation using operando TPR-DRIFTS-MS

Abstract

The noble metal-doped Mn2O3 catalyst has good activity at low temperature, but the structure-activity relationship between its catalytic activity and surface oxygen oxygens at low temperature is unclear. In this study, Mn2O3 and Ag-Mn2O3 prepared using aerosol pyrolysis method (Mn2O3-AP and Ag-Mn2O3-AP), and Ag-Mn2O3 prepared using co-precipitation method (Ag-Mn2O3-CP) are selected to unveil the effect of oxygen species (AgO, MnO, and Mn-O-Mn (Ag-O-Mn)) in CO oxidation. Ag-Mn2O3-AP has better CO conversion (100%) at 100 °C. Operando TPR-DRIFTS-MS results show that AgO plays an important role in CO oxidation at low temperatures. AgO starts to react with CO above 50 °C. Mn-□-Mn (Ag-□-Mn) oxygen vacancies are beneficial for O2 decomposition and promotes the regeneration of AgO and MnO, and Mn-O-Mn (Ag-O-Mn) above 200 °C. It is revealed that AgO in the Ag-doped Mn2O3 catalyst prepared using aerosol pyrolysis method effectively promoted the oxidation of CO at lower temperature.