Effect of CuO addition on the performance of V₂O₅-based oxygen carriers for chemical-looping oxidation of H₂S for efficient sulfur recovery from natural gas

Integrating Chemical-Looping process with Selective Oxidation of H₂S (CLSO) at low temperature is a novel method to achieve efficient desulphurization and sulfur recovery from nature gas. In CLSO process, a reducible catalytic oxygen carrier (COC) is need to cyclically transport oxygen from air to H₂S in gaseous fuels. For energy saving, it must have adequate catalytic sites that can selectively convert H₂S to elemental sulfur at temperature as low as possible, meanwhile COCs do not combust nature gas, and for continuously operation the reduced COCs can be fully regenerated with air. COC development is key issue for the successful deploying CLSO process. Based on CLSO concept given by previous work (Kane, 2019), this study developed various V₂O₅-based COCs with and without CuO addition using TiO₂- and Al₂O₃- supports of stable porous structures, trying to improve the overall performance of COCs. By cyclic CLSO experiments, the desirable features of the new COCs were examined, and the effects of CuO addition on oxygen transport, catalytic behaviors, and chemical stabilities were specially assessed. This study also revealed the selective oxidation reaction mechanisms of H₂S with these V₂O₅-based COCs, and identified the roles of CuO in catalytic redox reaction. It is demonstrated that the reactivities of V₂O₅ phase was greatly promoted as supported on porous supports; CuO phase enhanced significantly oxygen transport capacities of COCs as it was reduced to metallic copper in selective oxidation of H₂S. Elemental sulfur deposition, H₂S adsorption, and metallic sulfide formation put impacts to selectivity, and further study to improve COC selectivity is needed.