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

Cuong Duong-Viet,Cuong Pham-Huu,Lam Nguyen-Dinh,Yuefeng Liu,Giulia Tuci,Giuliano Giambastiani

doi:10.3390/molecules23071528

Abstract

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.

Highlights

Hydrogen sulfide (H2 S), which is contained in industrial effluent gas emissions, is one of the most hazardous elements with a very high environmental impact due to its toxicity [1], strong odor and corrosive effects [2,3]
The selected silicon carbides (SiCs) matrix was impregnated with a 5 wt.% aqueous solution of nickel nitrate before undergoing calcination
The most effective β-SiC support selected for the preparation of the desulfurization catalyst consists of cubic foams (4 × 4 × 4 mm; h × w × d, ~0.06 cm3 as average dimension) featured by relatively large cell sizes (20 pores per inch (PPI)) and narrow strut thickness (0.1 ÷ 0.15 mm) for an appropriate reactants accessibility and low pressure drop

Summary

Introduction

Hydrogen sulfide (H2 S), which is contained in industrial effluent gas emissions, is one of the most hazardous elements with a very high environmental impact due to its toxicity [1], strong odor and corrosive effects [2,3]. Most of the catalytic oxidation processes for the H2 S conversion to elemental sulfur are carried out in either discontinuous- or continuous-mode While in the former mode (typically operating at T < 180 ◦ C) sulfur is trapped inside the catalyst and its regeneration (sulfur melting/vaporization in an inert atmosphere at temperatures around 350 ◦ C) is periodically required; in the latter (T > 180 ◦ C), sulfur is continuously removed from the catalyst and accumulated in the solid state at the reactor outlet. For these processes, the sulfur yield commonly ranges between. Previous results obtained by some of us [8,9] showed that NiS2 supported on silicon carbide (SiC) grains

Methods

Results

Conclusion