The effect of W and Mo modification on arsenic adsorption over Cu/γ-Al2O3 catalyst: Experimental and theoretical analysis

Cu-based oxides are promising catalysts for selective catalytic reduction (SCR) at low temperatures, but their applications are inevitably restricted by the presence of heavy metals in the flue gas. In this work, the effect of W and Mo modification on arsenic adsorption over Cu/γ-Al2O3 catalyst was investigated. Results showed that both W-Cu/γ-Al2O3 and Mo-Cu/γ-Al2O3 catalysts exhibited superior NO conversion activities at low temperatures. W and Mo modification alleviated the arsenic adsorption on Cu/γ-Al2O3 catalyst, and further strengthened the arsenic resistance of the Cu/γ-Al2O3 catalyst. Moreover, the promotion effect of W modification on arsenic resistance was stronger than that of Mo modification, and the proportion of As5+ on W-Cu/γ-Al2O3 surface was larger than that on Mo-Cu/γ-Al2O3 surface. To clarify the effect of W and Mo modification on arsenic absorption, As2O3 adsorption on W-Cu/γ-Al2O3 and Mo-Cu/γ-Al2O3 surfaces was calculated via the density functional theory (DFT) method. Theoretical simulations indicated that As2O3 adsorption on Mo-Cu/γ-Al2O3 surface was stronger than that on the W-Cu/γ-Al2O3 surface. Compared with As2O3 adsorption on Cu/γ-Al2O3 surface, W modification converted the As2O3 adsorption from physisorption to chemisorption, explaining the experimental observation that W modification enhanced the As5+ proportion on catalyst surface.