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/SiC^foam 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/SiC^foam 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.