Low-Temperature Highly Efficient Catalytic Removal of Odorous Carbonyl Sulfide by Facile Regulating CeO2 Morphologies

Abstract

Unraveling the water activation is essential in the catalytic hydrolysis of organic sulfur compounds, yet its intrinsic mechanism of the water-promoting effect is still unclear. In this work, we describe novel findings of oxygen vacancy (V_O) engineering by facile regulating CeO₂ nanocatalysts with different shapes (rod, octahedral, sphere and cube) for COS hydrolysis at lower temperature, aiming at understanding the structural origin of the excellent catalytic hydrolysis activity. Unexpectedly, among CeO₂ catalysts with different morphologies, spherical CeO₂ (CeO₂-S) catalysts can achieve completely conversion of COS at 60 ℃ and maintain 30 hours of non-deactivation, which is a significant improvement in catalytic activity and reaction temperature compared to previously reported catalysts. Through various characterizations and results analysis, it is obvious to see that the more spontaneous formation V_O on CeO₂-S catalysts synergistically induced the water activation and dissociation thus result in the generation of more surface active hydroxyl groups (-OH), which contributes to the enhanced performance of COS catalytic hydrolysis at lower temperature. The promoting effect of catalyst morphology changes on COS hydrolysis were furthering analyzed using in situ DRIFTS and DFT calculations, and revealed that the exposed (111) crystal plane of CeO₂ exhibits the strongest adsorption capacity for COS. Notably, CeO₂-S also exhibited good catalytic performance and stability towards to other typical organic sulfur compounds (COS and CS₂), which is beneficial for the wide application at complex operating conditions. This study provides new insights for designing OH-rich CeO₂ catalysts to remove single as well as multi-component organic sulfur compounds for different applications at lower temperatures.