Microenvironment engineering for enhancing catalytic active sites for the CO oxidation reaction

The removal of carbon monoxide (CO) from sintering flue gases remains a significant challenge in industrial gas purification, requiring efficient catalytic systems. This study explores the use of TiO 2 synthesized under supercritical conditions in copper-based catalysts for low-temperature CO oxidation. Experimental results showed enhanced catalytic activity, with complete CO conversion at 120°C, primarily due to a higher Cu⁺ concentration in the catalyst. Characterization techniques (XPS, EPR, CO-DRIFT) confirmed a substantial increase in the Cu⁺ ratio in Cu/sc-TiO 2 (78%) compared to Cu/TiO 2 (71%) before thermal treatment. Additionally, the Cu/sc-TiO 2 -A catalyst exhibited smaller particle size and better dispersion, which contributed to the elevated Cu⁺ ratio after preheating. Thermal treatment increased the Cu⁺ ratio by 11% in Cu/sc-TiO 2 -A, compared to just 3% in Cu/TiO 2 -A, leading to a final Cu⁺ ratio of 89%, which enhanced catalytic activity. DRIFT and TPSR analyses indicated that the Cu/sc-TiO 2 catalyst generated CO during heat treatment, creating a micro-reduction environment that optimized copper valence states and active sites. This study highlights the potential of continuous hydrothermal flow synthesis for modulating catalyst valence states in industrial applications.