Oxygen Vacancy-Mediated Selective H₂S Oxidation over Co-Doped LaFe_xCo_1−xO₃ Perovskite

Abstract

Compared to the Claus process, selective H2S catalytic oxidation to sulfur is a promising reaction, as it is not subject to thermodynamic limitations and could theoretically achieve ~100% H2S conversion to sulfur. In this study, we investigated the effects of Co and Fe co-doping in ABO3 perovskite on H2S selective catalytic oxidation. A series of LaFexCo1−xO3 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) perovskites were synthesized by the sol-gel method. Compared to LaFeO3 and LaCoO3, co-doped LaFexCo1−xO3 significantly improved the H2S conversion and sulfur selectivity at a lower reaction temperature. Nearly 100% sulfur yield was achieved on LaFe0.4Co0.6O3 under 220 °C with exceptional catalyst stability (above 95% sulfur yield after 77 h). The catalysts were characterized by XRD, BET, FTIR, XPS, and H2-TPR. The characterization results showed that the structure of LaFexCo1−xO3 changed from the rhombic phase of LaCoO3 to the cubic phase of LaFeO3 with Fe substitution. Doping with appropriate iron (x = 0.4) facilitates the reduction of Co ions in the catalyst, thereby promoting the H2S selective oxidation. This study demonstrates a promising approach for low-temperature H2S combustion with ~100% sulfur yield.

Keywords

• hydrogen sulfide
• selective oxidation
• perovskite oxides
• oxygen vacancy