Enhanced Activity and Water Resistance on CuO/SiO2-TiO2 Catalyst for CO Oxidation and NO Reduction by CO: The Promotion Effect of SiO2

Abstract

Non-precious metal catalysts with enhanced low-temperature activity and improved water resistance are highly demanded for emission control. CuO-based catalysts are promising alternatives to precious metal catalysts due to their acceptable activity and cost-effectiveness. However, there is an urgent need to further enhance their low-temperature activity and water resistance for industrial applications. Herein, CuO catalysts supported by various SiO₂-TiO₂ supports were prepared and evaluated for CO oxidation and NO reduction by CO reactions under the testing conditions with and without water. Among the studied catalysts with different SiO₂ contents, CuO/5SiO₂-TiO₂, in which CuO was supported by SiO₂-TiO₂ with 5 wt.% SiO₂, exhibited the best performance for CO oxidation. Compared with CuO/TiO₂ and CuO/SiO₂ reference catalysts, the CuO/5SiO₂-TiO₂ catalyst showed enhanced catalytic activity in both CO oxidation and NO reduction by CO under dry and wet conditions. Comprehensive characterizations revealed that the presence of SiO₂ in TiO₂ support facilitated the CuO/5SiO₂-TiO₂ catalyst with a high dispersion and reduced oxidation states of CuO_x species. This not only improved the low-temperature reducibility but also enhanced the adsorption of reactive CO species. As a result, the CuO/5SiO₂-TiO₂ catalyst demonstrated superior catalytic activity. Furthermore, the inclusion of SiO₂ in the catalyst inhibited H₂O adsorption, contributing to the enhanced water resistance on CuO/5SiO₂-TiO₂ catalyst. These advantages in catalytic activity and water resistance make CuO/5SiO₂-TiO₂ a promising candidate for applications in emission control.