Highly active alkali etching silica-modified Cu-Ce-Ti catalyst with superior water resistance for low temperature NOx reduction

Abstract

In this study, Cu-Ce oxides supported on a silica modified TiO2 with post-alkali treatment (Cu-Ce/TS-am) were synthesized to enhance the catalytic activity and water resistance for low-temperature NOx reduction with ammonia. Experiment results revealed that the optimal Cu-Ce/TS-am sample possessed over 90% NOx conversion at 180–350 °C in the presence of 10 vol% water. Essentially, the formed Ti-Si strong interactions after Si addition could be responsible for that. On the one hand, the interactions increased specific surface area, total acidity and oxygen mobility, thus promoting SCR activity. On the other hand, it could enhance the hydrophobicity of the catalysts as there existed lower surface roughness, smaller particle size and enlarged mesoporous pore size after Si addition, alleviating the competitive adsorption of water with NH3. Additionally, the alkali treatment removed uncombined SiOx, which optimized the mesoporous pore structure and increased the exposure of active sites and acidic sites on the catalyst surface, further enhancing water resistance and catalytic activity. These findings could provide useful guidelines for the development of highly active SCR catalyst with well water resistance in real application.