SCR of NO by DME over Al2O3 based catalysts: Influence of noble metals and Ba additive on low-temperature activity

The selective catalytic reduction (SCR) of NO by dimethyl ether (DME) has been investigated over various noble metal loaded Al2O3 catalysts. It was found that Ag loaded Al2O3 was much more active than Rh, Pd, and Pt loaded ones. Further improvement of the low-temperature performance of Ag/Al2O3 between 200 °C and 300 °C was attempted by the addition of various amounts of Ba species; an Al2O3 supported Ag (1 wt.%) catalyst promoted by 0.2 wt.% Ba was the most effective for DME-SCR. UV–vis spectra showed that Ag+ ion played an important role in the reaction and the addition of Ba increased the amount of this active species. Furthermore, FTIR measurements indicated that the formation of such reaction intermediates as –NCO and –CN was promoted by the isolated Ag+ ions, resulting in the higher activity for DME-SCR.