A comprehensive exploration about the effects of O2, SO2 and NO on As2O3 adsorption over Cu/γ-Al2O3 SCR catalyst: A DFT study

Abstract

Identifying the mechanisms by which gas components influence arsenic deposition over a SCR catalyst is an important issue to protect the catalyst from arsenic poisoning. In this work, the effects of O2, SO2, and NO on arsenic adsorption over a Cu/γ-Al2O3 catalyst were calculated via density functional theory (DFT) method. Results revealed that O2 facilitated the As2O3 retention on Cu/γ-Al2O3 surface due to the formation of adsorbed O atoms. The positive effect of SO2 on As2O3 adsorption was reflected by the formation of SO42− and HSO4−, which changed the potential field of substrate surface. Specifically, HSO4− enhanced the adsorption activities of surface atoms. However, NO3− did not show a significant impact on As2O3 adsorption when NO was introduced. From thermodynamic and adsorption selectivity analysis, the adsorption activities of different surfaces were in the order of O-Cu/γ-Al2O3 > SO42−-Cu/γ-Al2O3 > O2-Cu/γ-Al2O3 > NO3−-Cu/γ-Al2O3 > HSO4−-Cu/γ-Al2O3. However, the adsorption selectivity weakened with increasing temperature. Results from this work can help improve the arsenic resistance of SCR catalysts.