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/gamma-Al2O3 catalyst was investigated. Results showed that both W-Cu/gamma-Al2O3 and Mo-Cu/gamma-Al2O3 catalysts exhibited superior NO conversion activities at low temperatures. W and Mo modification alleviated the arsenic adsorption on Cu/gamma-Al2O3 catalyst, and further strengthened the arsenic resistance of the Cu/gamma-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/gamma-Al2O3 surface was larger than that on Mo-Cu/gamma-Al2O3 surface. To clarify the effect of W and Mo modification on arsenic absorption, Al2O3 adsorption on W-Cu/gamma-Al2O3 and Mo-Cu/gamma-Al2O3 surfaces was calculated via the density functional theory (DFT) method. Theoretical simulations indicated that Al2O3 adsorption on Mo-Cu/gamma-Al2O3 surface was stronger than that on the W-Cu/gamma-Al2O3 surface. Compared with As2O3 adsorption on Cu/gamma-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.

Automated summary

This study investigated the effect of W and Mo modification on arsenic adsorption over Cu/gamma-Al2O3 catalyst. Results showed that W and Mo modification improved the NO conversion activities at low temperatures and reduced the arsenic adsorption on Cu/gamma-Al2O3 catalyst. W modification had a stronger promotion effect on arsenic resistance compared to Mo modification, and the proportion of As5+ on the W-Cu/gamma-Al2O3 surface was larger than that on the Mo-Cu/gamma-Al2O3 surface. Theoretical simulations revealed that Al2O3 adsorption on Mo-Cu/gamma-Al2O3 surface was stronger than that on W-Cu/gamma-Al2O3 surface.