Promoting effect of Au on Pd/TiO2 catalyst for the selective catalytic reduction of NOx by H2

Au promoted Pd/TiO2 catalysts with different Pd loading were investigated for the selective catalytic reduction of NOx by hydrogen (H-2-SCR). The results showed that 1% Pd-0.5% Au/TiO2 catalyst exhibited the highest NOx conversion and N-2 selectivity, as well as a wide activity temperature window. Moreover, the 1% Pd-0.5% Au/TiO2 catalyst offered remarkable resistance to high gas hourly space velocity (GHSV). XRD, XPS and TEM results illustrated that the excellent H-2-SCR performance of 1% Pd-0.5% Au/TiO2 catalyst was closely related to the formed PdAu alloy and the higher dispersion of active sites compared with 1% Pd/TiO2. In-situ DRIFTS results revealed that more and new adsorbed nitrogen oxides species, as well as more adsorbed NH3 and NH4+ active species generated over 1% Pd-0.5% Au/TiO2 catalyst, thus accelerating the ability to active H-2 atom and the subsequent reaction with adsorbed nitrogen oxides species.