Novel ZnO-NiO-graphene-based sorbents for removal of hydrogen sulfide at intermediate temperature

Abstract

When syngas is upgraded to bio-refinery products, hydrogen sulfide removal is necessary to prevent corrosion of equipment and avoid poisoning of sulfur sensitive catalysts. Technologies relying on sorbents working in the 300–500 °C temperature range are desirable for better process integration. In this work, a new family of reduced graphene ZnO-NiO sorbents, Zn-Ni-rGO, were synthesized by non-expensive and easily replicable scalable methods and studied for the first time for hydrogen sulfide reactive adsorption. Preparation was based on the Hummers & the improved Tour methods followed by addition of Zn(NO3), Ni(NO3), hydrothermal reduction and annealing. As obtained as well as post-reaction rGO-NiO-ZnO sorbents were characterized by XRF, XRD and N2 adsorption at −196 °C. The performance of the sorbents for fixed bed desulfurization was determined at lab-scale (P = 10 bar, T = 400 °C, GHSV = 3500 h−1) on a gas stream containing 9000 ppmv of H2S/N2. The sorbents showed better hydrogen sulfide removal capacity than the commercial one studied for comparison, what makes them a potential candidate for gas cleaning in the syngas-related sectors.