Research progress of catalytic oxidation technologies of hydrogen sulfide

With the development of the economy and increasingly regard on environment protection, a series of measures were formulated and strict regulations on hydrogen sulfide (H₂S) emission were established by the state. The removal of H₂S has been the focus of material research and development, and catalytic oxidation is considered as a main method for H₂S removal. Two kinds of catalysts including carbon-based catalysts (unsupported activated carbon, metal-supported activated carbon) and metal oxide-based catalysts (oxide-supported catalyst, metal oxide catalyst, anionic clay-supported catalyst) have been widely studied. The catalytic oxidation mechanism of H₂S, preparation method for these two catalysts and H₂S removal efficiency as well as the potential applications of these catalysts were discussed in detail. Carbon materials had become a popular choice as catalyst or support due to their large specific surface area, high porosity and modifiable active sites. Meanwhile, they were usually operated at relatively low temperatures and showed a good stability, and no strict stoichiometric ratios of O₂/H₂S was needed during H₂S treatment process. However, such catalysts could only treat low concentrations of H₂S and operated at lower hourly space velocity. In addition, the catalysts should be regenerated periodically after a period of use. As for metal oxide catalyst , they could treat high concentrations of H₂S and showed a good catalytic performance even at higher temperatures (200-300 ℃), but the cost of the catalysts was high due to the strict O₂/H₂S stoichiometric ratio, high temperature and poor regenerability. Nitrogen-rich porous carbon and alkali metal-loaded alkaline millimeter mesoporous carbon spheres (MCS) exhibited excellent catalytic performance. On this basis, the future development direction of H₂S catalytic oxidation was addressed.