Deciphering the mechanisms of plasma-enhanced CO reduction of SO2 on Ag-based catalysts supported by Al2O3: An in-situ desorption approach

Since the catalytic mechanism of mild and efficient non-thermal plasma (NTP)-enhanced catalytic techniques are not clear, the reduction of SO2 2 by CO was used as a probe reaction, decoupling gas-phase and surface reactions using online adsorption-desorption methods. Catalysts were gamma- Al 2 O 3 loading with 10 wt% Ag, Ag2O, 2 O, and Ag2S. 2 S. In the gas phase, excited reactant molecules produce mainly COS. In catalyst surfaces, SO2 2 exhibited Type I-V adsorption states, with Types IV-V being the main reactants. The crystal phase transformation Ag2O-Ag2CO3-Ag 2 O-Ag 2 CO 3 - Ag in the Ag2O-loaded 2 O-loaded catalyst confirmed that SO2 2 undergoes unidirectional oxidation. The Ag2S-loaded 2 S-loaded catalyst not only adsorbed more Type IV-V SO2, 2 , but also could react directly with SO2 2 to form S and S defects, and then effectively utilize the intermediate product COS to regenerate Ag2S, 2 S, which also yielded the best desulfurization performance. Based on the above findings, a novel E-R desulfurization mechanism under NTP enhancement is proposed.