Bimetallic Ag-based catalysts for low-temperature SCR: Quo vadis?

The abatement of nitrogen oxides coming to the atmosphere from diesel engines of automotive vehicles and marine vessels, industrial plants, and other sources is of profound importance. Currently, catalysis-based solu-tions show growing potential in addressing this challenge. The main requirements that SCR catalysts should meet include enhanced low-temperature activity and selectivity combined with a broad operating window, high resistance to poisons and moisture. While a plethora of SCR catalysts has been proposed by now, recently, a growing number of publications have emphasized the unlocked potential of bimetallic catalyst formulations. Among them, Ag-based systems deserve special attention due to their high performance and relative cheapness. The present review is focused on the recent achievements recorded in the latest 5-10 years on bimetallic Ag-based catalysts for low-temperature SCR. Systems, such as Ag-Pt, Ag-Au, Ag-Cu, Ag-Fe, Ag-Mn, are considered and compared with bi-and polymetallic transition metals. The role of catalysts preparation method, Ag loading, metal-support interaction and pre-treatment effects has been pointed out. The outlook of the future research challenges is provided.