High conversion of H₂S to H₂ and S via a robust microwave-induced discharge plasma

Direct conversion of H2S could achieve the co-production of hydrogen and sulfur, avoiding hydrogen waste in the traditional Claus process. Herein, we propose a robust SiC-mediated microwave-induced discharge plasma, achieving H2S conversion of 98.8% to H-2 and S with the inlet H2S of 2% (volume concentration) at 600 W. We realize efficient excitation and stable maintenance of microwave plasma in the multimode cavity via optimizing large SiC particles at the waveguide port. In addition, the introduction of tungsten sheets enhances discharge plasma. The H2S conversion of 52.8% was realized for the high inlet H2S concentration (30%) at 600 W. In-situ optical emission spectroscopy reveals that atomic S and H are the key reactive intermediates in the overall H2S decomposition. Direct electron-H2S collision coupling excited Ar atom-H2S collision contributes to H2S direct conversion. This work paves a path to hydrogen production toward sustainable energy applications from the direct conversion and utilization of H2S.