Perspectives in the Synergetic Photothermocatalysis of Hydrogen Sulfide Decomposition for Hydrogen Production: A Comprehensive Review

Acid gas, which contains toxic hydrogen sulfide, is produced by several sources, including refineries and processing plants for natural gas. Catalytic decomposition and reforming of H2S offer viable ways to produce hydrogen from a waste resource, with the added benefit of reducing pollution. However, the conventional thermolysis of hydrogen sulfide, including the traditional Claus process, is highly endothermic and exhibits low conversion at low reaction temperatures. While the photocatalytic pathway would offer a less energy-intensive pathway, its overall efficiency regarding light/heat absorption and utilization needs to be further enhanced. Hydrogen sulfide can be converted via photothermocatalysis into elemental sulfur and hydrogen, two value-added products. This process addresses the drawbacks of pure photo and thermal procedures and could be a viable approach to treating hydrogen sulfide waste streams. This study extensively examines the potential interaction between photo- and thermocatalytic systems, concentrating on the conversion of hydrogen sulfide to hydrogen. The aim is to provide valuable insights and pathways for future optimization. For the first time, as per the literature survey, a photothermocatalytic process that could be extended to both hydrogen sulfide decomposition and reformation toward hydrogen production is proposed, considering current challenges and prospects.