Improving NH3-SCR denitrification performance over WaCo0.4TiOx catalysts: Effect of surface acidity due to W addition on low-temperature and high-temperature activity

Abstract

A serial of WaCo0.4TiOx catalysts (a = 0.04, 0.06, 0.08, 0.10) was synthesized by sol-gel method, which exhibited high NH3-SCR denitrification performance in a wide activity temperature window. W0.08Co0.4TiOx achieve best SCR activity (over 90% NO conversion) at 190–430 °C and good resistance to H2O/SO2. Various characterizations were used to investigate the influence of W doping on physicochemical property of these catalysts. Especially, in-situ DRIFTS were used to evaluate the type of acid sites, NOx adsorption, the reactivity of surface adsorption species, and the influences of H2O/SO2 on adsorption of NOx and NH3. The doping of W enhanced the acidity and weakened the oxidation capacity of WaCo0.4TiOx, but higher surface acidity, especial more Brønsted acid sites, can compensate for the effect of the decrease in the oxidation capacity on low-temperature activity. The optimal activity over W0.08Co0.4TiOx can be derived from the synergistic effect of surface acidity and oxidation performance.