Improved K-Resistance of a Cu-Modified TiO2/CeO2 Catalyst for SCR of NOx at Low Temperatures

The employment of CeTi-based catalysts in the denitration of exhaust from biomass combustion is significantly limited by the poor tolerance to alkali metals. Herein, a CuO modification strategy was proposed to enhance the resistance of CeTi catalysts to K2O. The NO conversion of pristine Ti/Ce decreased from 95% to less than 10% at 250 °C after 1 wt % K loading. As a sharp comparison, CuO-modified Ti/Ce reserved more than 70% in NO conversion under the same test conditions. Combined with diverse characterizations, it was found that the addition of CuO promoted the formation of Cu–O–Ce and Cu–O–Ti species, which showed enhanced redox and acid properties. CuO modification also suppressed the adsorption of inert nitrates resulting from K loading. Moreover, Brønsted acid sites introduced by CuO served as capture sites of alkali metals, thus alleviating the active sites from being poisoned. More retained acidic and redox capacities ensured the excellent catalytic performance of TiCu/Ce under K poisoning.