Research on the removal of As2O3 by γ-Al2O3 adsorption based on density functional theory.

In order to protect selective catalytic reduction (SCR) catalysts for flue gas denitration in coal-fired power plants, the adsorption of As2O3 on γ-Al2O3(0 0 1) surface is investigated theoretically through density functional theory (DFT) in this study. The adsorption sites, adsorption structures, adsorption energies, electronic clouds, transition processes, and intermediate and transition structures are investigated. The theoretical results indicate that the adsorption of As2O3 molecule on the surface of γ-Al2O3(0 0 1) could be either physical or chemical, depending on the sites the molecule hangs over. Compared with the experimental results from other researchers, this study unveils that, although the apparent adsorption of As2O3 molecule on γ-Al2O3(0 0 1) surface is physical, some of the sites on γ-Al2O3(0 0 1) surface presents strong chemical affinity towards As2O3 adsorption. Further, this study depicts the adsorption process to clarify the reason of the net effect of As2O3 adsorption on γ-Al2O3 being physical. Meanwhile, the study also reveals that apparent physical adsorption of As2O3 on γ-Al2O3(0 0 1) surface is due to the high energy barrier that prohibits the transformation of physical adsorption to chemical adsorption. The research results provide useful information for exploiting γ-Al2O3 as a potential metal oxides sorbent.