Nickel Sulfides Decorated SiC Foam for the Low Temperature Conversion of H2S into Elemental Sulfur

The selective oxidation of H2S to elemental sulfur was carried out on a NiS2/SiCfoam catalyst under reaction temperatures between 40 and 80 ◦C using highly H2S enriched effluents (from 0.5 to 1 vol.%). The amphiphilic properties of SiC foam provide an ideal support for the anchoring and growth of a NiS2 active phase. The NiS2/SiC composite was employed for the desulfurization of highly H2S-rich effluents under discontinuous mode with almost complete H2S conversion (nearly 100% for 0.5 and 1 vol.% of H2S) and sulfur selectivity (from 99.6 to 96.0% at 40 and 80 ◦C, respectively), together with an unprecedented sulfur-storage capacity. Solid sulfur was produced in large aggregates at the outer catalyst surface and relatively high H2S conversion was maintained until sulfur deposits reached 140 wt.% of the starting catalyst weight. Notably, the spent NiS2/SiCfoam catalyst fully recovered its pristine performance (H2S conversion, selectivity and sulfur-storage capacity) upon regeneration at 320 ◦C under He, and thus, it is destined to become a benchmark desulfurization system for operating in discontinuous mode.