Promotion Effect and SO2 Tolerance of Sb-Modified Ce-Co/TiO2 Catalyst for Low-Temperature Selective Catalytic Reduction of NOx with NH3

Ce-based catalysts have shown exceptional performance in selectively reducing NOx at low temperatures through selective catalytic reduction (SCR), while the poor SO2 tolerance and stability in the low-temperature range limit their practical applications. Using the sol-gel method, a series of Ce-Co/TiO2 catalysts were created. The SO2 tolerance of Ce-Co/TiO2 catalysts can be improved by Sb doping. The Ce-Co-0.02-Sb-0.02/TiO2 catalyst exhibited superior NO conversion and the best SO2 resistance, and the stability of the catalysts was enhanced. When exposed to 100 ppm of SO2 at 220 degrees C in 600 min, over 80% NO conversion can be maintained. Physicochemical properties and structural effects were systematically investigated through various characterizations. The experimental data indicated that the surface area of catalysts was increased by increasing the modification of Co. The Ce-Co-0.02-Sb-0.02/TiO2 catalyst was observed to have an increase of adsorbed oxygen (O-alpha) due to the combined impact of Sb and Co, facilitating the adsorption and activation of NO molecules and the reaction with NH3 molecules. The weak acid sites of all catalysts significantly influenced the SCR reaction. Further, the NH3-SCR reaction over Ce-Co-Sb/TiO2 catalysts followed Langmuir-Hinshelwood and Eley-Rideal mechanisms, with the Eley-Rideal mechanism potentially dominant.