Effects of O₂ and SO₂ on As₂O₃ adsorption over W-Cu/γ-Al₂O₃ surface: An experimental combined theoretical analysis

In this work, the effects of O₂ and SO₂ on gaseous As₂O₃ adsorption over W-Cu/γ-Al₂O₃ catalyst were investigated through adsorption experiment and density functional theory (DFT) method. Experimental results show that the As₂O₃ adsorption is facilitated by O₂, and intensified with the increasing concentrations of SO₂. However, it is slightly weakened with the SO₂ concentration of 2.0×10⁻³. The As₂O₃ adsorption on W-Cu/γ-Al₂O₃ surface with adsorbed gas constituents was calculated by DFT simulation to reveal the effect mechanism. The promoting effect of O₂ on arsenic adsorption is attributed to the formation of adsorbed oxygen. The pre-adsorbed O atom significantly enhances the adsorption activities of adjacent atoms, and the pre-adsorbed O₂ molecule provides the active sites for As₂O₃ adsorption. When SO₂ is introduced, the \rmSO^2- _4 and \rmHSO^-_4 are formed, which change the potential field of substrate surface, and further enhance the As₂O₃ adsorption. However, the competitive adsorption between SO₂ with As₂O₃ is strengthened with increasing SO₂ concentration, and it is the reason for the decreasing trend of As₂O₃ adsorption with high concentrations of SO₂.