Theoretic Insight into the Desulfurization Mechanism: Removal of H2S by Ceria (110)

Abstract

The periodic DFT+U calculation has been carried out to elucidate the desulfurization mechanism of H2S with the ceria (110) surface. The calculations show that the H2S molecule dissociatively adsorbs on the stoichiometric and reduced ceria (110) surfaces, respectively. The desulfurization process with the ceria (110) surface mainly contains two steps. First of all, H2S interacts with the stoichiometric surface, and the SO2-forming path is the most favorable reaction route based on the kinetics analysis. Meanwhile, surface O vacancies are created, and the reduced surface is formed. In this process, S in H2S is transferred to another sulfur-containing compound, SO2, which could not reduce the sulfur content in coal gas. Second, S in H2S is captured by filling into the O vacancy and forming CeOS species on the reduced surface. Therefore, it can be inferred that the key to the desulfurization of H2S in coal gas with ceria (110) is that more surface O vacancies are created.