Enhanced catalytic activity over MIL-100(Fe) with coordinatively unsaturated Fe2+/Fe3+ sites for selective oxidation of H2S to sulfur

The selective oxidation of H2S, which can eliminate H2S and recover sulfur as a useful resource, is a promising strategy because of its low capital cost and thermodynamically unlimited nature. However, there are obstacles in the development of stable and efficient catalysts to meet the needs of practical cases. Herein, we disclose the use of porous MIL-100(Fe) with coordinatively unsaturated (CUS) Fe2+/Fe3+ sites (denoted as CUS-MIL-100(Fe)) as efficient and stable catalyst for H2S removal. The catalyst is prepared via a simple hydrothermal process using iron powder and 1,3,5-benzenetricarboxylates (H3BTC) as raw materials, and its physicochemical properties have been studied by XPS, BET, ICP-OES, EPR, XRD, and in-situ DRIFTS techniques. The results reveal that the desulfurization performance of the CUS-MIL-100(Fe) catalyst is higher than that of commercial Fe2O3, achieving near 100% H2S conversion and 100% S selectivity at 100–190 °C. Importantly, the H2S conversion and S selectivity over CUS-MIL-100(Fe) are 100% and 95.1% in a continuous run of over 100 h, while those of Fe2O3 are only 42.6% and 19.4% after 13 h. This can be ascribed to the unique characteristics of CUS-MIL-100(Fe), such as the presence of Fe2+/Fe3+ CUSs, large specific surface area, and regular pore structure.