H2S selective catalytic oxidation over Ce substituted La1−xCexFeO3 perovskite oxides catalyst

Abstract

A series of La1−xCexFeO3 perovskite catalysts were synthesized using a citrate sol-gel method and examined for H2S selective catalytic oxidation reaction. It was demonstrated that the catalysts exhibited prominent catalytic activity, outstanding sulfur selectivity (nearly 100%) and particularly low apparent activation energy. Remarkably, it can proceed consecutively for 70 h without notable deactivation. Moreover, Ce and Fe were mainly existed in the form of LaCeFeO3 perovskite-type oxides as well as Ce-Fe solid solution. Significantly, catalysts reducibility was improved greatly due to the strongly Ce-Fe synergetic effect. More importantly, a proper substitution of Ce can enhance surface basic properties and facilitate the formation of oxygen vacancies on the catalyst surface, and hence improve H2S adsorbability and lattice oxygen mobility, respectively. It cooperating with the improved reducibility jointly contributed to the excellent catalytic performance. Furthermore, the reaction obeyed a redox mechanism and the catalyst deactivation was due mainly to the formation of sulfate species. Additionally, the added water can lead to the establishment of the reverse Claus reaction, causing the decrease of catalytic performance.