Promoting Effects of CuSO4 Modification on N2 Selectivity of 1Ru/5Ce-TiO2 Catalyst for Selective Catalytic Oxidation of NH3

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Abstract xCu+1Ru/5Ce-TiO2 catalysts were prepared by a grinding method to improve the NH3–SCO performance of 1Ru/5Ce-TiO2. The results revealed a marked promotion of N2 selectivity over 1Ru/5Ce-TiO2 upon CuSO4 incorporation. In particular, the 5Cu+1Ru/5Ce-TiO2 catalyst exhibited the optimal surface acidity, achieving over 70% N2 selectivity at 300 °C, which was noticeably higher than the 45% N2 selectivity of 1Ru/5Ce-TiO2. A systematic study was conducted to compare the 1Ru/5Ce-TiO2 and xCu+1Ru/5Ce-TiO2 catalysts in terms of their textural and structural properties, surface chemical states, redox and acid properties, and catalytic performance. The results indicate that the introduction of CuSO4 improves the dispersion of active sites, promotes the formation of Cu–Ce interfaces, increases the number of surface acid sites, enhances the redox properties, and facilitates the generation of reactive oxygen species. More importantly, CuSO4 addition alters the NH3 oxidation pathway by promoting the formation of HNO and NHx intermediates, thereby directing the reaction toward the desired N2 product. This study provides new insights into the rational design of efficient and selective NH3–SCO catalysts via strategic metal modification.