Synergistic effect of Ce doping and phosphorylation on optimizing the low temperature NH 3 -SCR activity of the spent V 2 O 5 -WO 3 /TiO 2 catalyst

Abstract

The reactivation and subsequent reuse of the exhausted SCR catalyst holds significant economic and environmental advantages. Water and acid washing along with thermal regeneration were commonly utilized to eliminate toxic substances from the catalyst surface, while these processes often resulted in the undesired loss of active components. In this research, an impregnation approach was adopted to replenish the depleted active constituents of the spent V2O5-WO3/TiO2 catalyst (denoted as VW/Ti). Experimental investigations were conducted to evaluate the influence of Ce/P doping on both the Selective Catalytic Reduction (SCR) activity of this rejuvenated catalyst and its resistance to the detrimental effects of SO2/H2O exposure. The optimal performance is achieved with the Ce/P co-doped VW/Ti catalyst, demonstrating a remarkable efficiency in removing nearly 100% of NOx across a broad temperature ranging from 150°C to 450°C. The incorporation of a proper content of Ce serves to elevate the VOx surface density from a sub-monolayer state to a monolayer and foster the formation of more surface oxygen vacancy. This transformation positively contributes to enhancing both the catalytic activity and the resistance to the SO2/H2O poisoning. Further treatment with H3PO4, although rendering the catalyst more susceptible to H2O, achieves a delicate balance between its surface acidity and redox capabilities. This optimized state not only enhances the catalyst's robustness but also further widens the active temperature window.