WO3-V2O5 Active Oxides for NOx SCR by NH3: Preparation Methods, Catalysts' Composition, and Deactivation Mechanism-A Review

Researchers in the field of the selective catalytic reduction (SCR) of nitrogen oxides (NOx: NO, NO2, or N2O) by NH3 are still greatly challenging the optimization of low-temperature activity and selectivity, high-temperature stability, resistance to alkali metals and other poisoning agents, such as Hg, As, etc. The present study reviews the research progress, related to the latest 20 years, on WO3-V2O5-based catalysts that are expected to overcome the catalytic performances of the current SCR catalytic devices. In details, the effects of the synthesis methods, chemical composition, type of supports (metal oxides, molecular sieves, and filters), doping elements, or metal oxides added as promoters of WO3-V2O5-based catalysts and, finally, the influence of SO2 and H2O in the reaction mixture are addressed. The importance of understanding the deactivation mechanism in the presence of several poisoning agents is also emphasized, which should be taken into consideration for the design of new catalysts.