| Summary: | Published papers highlight the roles of the catalysts in plasma catalysis systems, and it is essential to provide deep insight into the mechanism of the reaction. In this work, a coaxial dielectric barrier discharge (DBD) reactor packed with γ-MnO<sub>2</sub> and CeO<sub>2</sub> with similar nanorod morphologies and particle sizes was used for methanol oxidation at atmospheric pressure and room temperature. The experimental results showed that both γ-MnO<sub>2</sub> and CeO<sub>2</sub> exhibited good performance in methanol conversion (up to 100%), but the CO<sub>2</sub> selectivity of CeO<sub>2</sub> (up to 59.3%) was much higher than that of γ-MnO<sub>2</sub> (up to 28.6%). Catalyst characterization results indicated that CeO<sub>2</sub> contained more surface-active oxygen species, adsorbed more methanol and utilized more plasma-induced active species than γ-MnO<sub>2</sub>. In addition, in situ Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR) were applied with a novel in situ cell to reveal the major factors affecting the catalytic performance in methanol oxidation. More reactive oxygen species (O<sub>2</sub><sup>2−</sup>, O<sup>2−</sup>) from ozone decomposition were produced on CeO<sub>2</sub> compared with γ-MnO<sub>2</sub>, and less of the intermediate product formate accumulated on the CeO<sub>2</sub>. The combined results showed that CeO<sub>2</sub> was a more effective catalyst than γ-MnO<sub>2</sub> for methanol oxidation in the plasma catalysis system.
|
|---|