Nanorod Al2O3 catalysts for simultaneous hydrolytic removal of COS and CS2 via crystal surface modulation: Experimental and theoretical studies

Abstract

The undesirable stability and vulnerability to poisoning of catalysts have posed a great obstacle to the development of organosulfur hydrolysis technology. In this paper, H-K0.1Al2O3 nanorod catalysts with exposed Al2O3(111) crystal plane were prepared by hydrothermal synthesis. The results indicated that the COS and CS2 hydrolysis activity at low temperatures of the H-K0.1Al2O3 catalyst was significantly higher than that of K0.1Al2O3. In the presence of 0.01 vol% HCl, there was no decrease in the COS conversion of H-K0.1Al2O3 after 12 h of reaction. The CS2 conversion was stable at about 65 %. Characterization results revealed that the improved hydrolysis performance was mainly related to enhanced surface alkalinity and more oxygen vacancies, which strengthened the adsorption capacity of the reactive molecules. The results of DFT calculations proved the stronger adsorption ability of the Al2O3(111) plane than the Al2O3(110) plane. The suppressed HCl adsorption contributed to the enhanced resistance to chlorine poisoning. Reaction path calculations demonstrated that the H2O molecules on the Al2O3 (111) dissociated more rapidly to produce –OH, and the intermediates -CS2OH and -HSCO were more easily generated with lower reaction energy barriers.