Effects of O₂, SO₂, H₂O and CO₂ on As₂O₃ adsorption by γ-Al₂O₃ based on DFT analysis

In order to reveal the affecting mechanisms of flue gas on As₂O₃ adsorption by γ-Al₂O₃ and to enhance the adsorbing capacities of γ-Al₂O₃, the influences of flue gas constituents on As₂O₃ adsorption on γ-Al₂O₃(0 0 1) surface are investigated theoretically via density functional theory (DFT) in this study. The flue gas constituents selected include O₂, H₂O, SO₂ and CO₂. O₂ converts nearly all of the physisorption structures into chemisorption structures except one structure, in which the O₂ electron cloud does not interact with As₂O₃ molecule and therefore does not enhance the capture of As₂O₃. For the effects of H₂O, SO₂ and CO₂, they behave almost the same as those of O₂, but the physisorption structures vary from different constituents. The difference of stable adsorption structures of O₂, H₂O, SO₂ and CO₂ on the surface of γ-Al₂O₃ and their corresponding properties are the main reason for variance of positions and quantities of As₂O₃ physisorption structures. Results of this study could provide useful information for enhancing capture capacities of γ-Al₂O₃ under actual flue gas environments.