Revealing the significant differences of CO plasma oxidation on β-MnO2 catalyst in in- and post-plasma catalysis configurations using operando DRIFTS-MS

The position of the catalyst in a plasma reactor has an important effect on performance of plasma driven catalytic reaction. An operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and mass spectrometry (MS) has been used to investigate CO oxidation on MnO 2 catalyst in in-plasma catalysis (IPC) and post-plasma catalysis (PPC) configurations. It was found that the catalyst in IPC configuration has higher CO conversion and CO 2 selectivity than that in PPC configuration. Operando DRIFTS-MS analysis showed that the IPC configuration generated more reactive oxygen species (M O) on the catalyst surface than the PPC configuration, where M O, M 2+ -O 2 2– , and M + O 2 – are important reactive species promoting CO oxidation to monodentate carbonate that is easy to gasify to gaseous CO 2 . The physical adsorbed O 3 on the catalyst in PPC configuration converts to M 2+ -O 2 2– which combines with CO to form bidentate carbonates that is difficult to gasify to gaseous CO 2 . The mechanisms of CO oxidation on the catalyst in IPC and PPC configurations are discussed.