A novel CuTi-containing catalyst derived from hydrotalcite-like compounds for selective catalytic reduction of NO with C3H6 under lean-burn conditions

• CuTi-containing catalyst derived from hydrotalcite-like used for NOx removal.
• Cu can be categorized into surface and bulk species of the CuTi-containing catalyst.
• Surface Cu is active site, while bulk Cu possesses adsorption property.
• Lewis acid sites actively contribute to the catalytic performance.
• Nitrates, acetate and formate are evidenced as key intermediates for NOx removal.

A series of hydrotalcite-based CuxTi1 (x = 2, 3, 4, 5)-mixed oxide catalysts have been synthesized by homogeneous precipitation and tested in the selective catalytic reduction (SCR) of NO by C3H6 in the presence of excess oxygen. Cu atoms can be categorized into surface and bulk species. The surface Cu species are the active sites while the bulk Cu species possess adsorption property for nitrogen species, and such bulk Cu species varies from CuxTiyOz to CuO with increasing Cu content. The Cu3Ti1 catalyst with the highest amount of surface copper and Lewis acid sites exhibits the best catalytic performance due to its improved electrophilicity of CuxTiyOz, which enhance the adsorption capability of nitrogen species. In situ infrared characterization revealed that nitrates in terms of bridging, bidentate and chelating species are reactive toward acetate and formate, and they are the key intermediates produced during the SCR of NO.

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