Experiment and mechanism research on gas-phase As2O3 adsorption of Fe2O3/γ-Al2O3

Fe2O3/gamma-Al2O3 sorbents that containing different quantities of iron (III) oxide were prepared by ultrasound-assisted wet impregnation method. Application of these sorbents for arsenic adsorption was tested on a fixed bed reactor and some factors, such as temperature, precursor solution concentration (PSC) and SO2/NO concentration were discussed. The results indicated that more than 65% of gas-phase arsenic was adsorbed at 600 degrees C, while the efficiency decreased gradually when temperature over 600 degrees C. The higher precursor solution concentration could increase the amount of active substance on carrier, but also cause structure deterioration of sorbent. SO2 in flue gas exhibited a promotion effect on arsenic adsorption across Fe2O3/gamma-Al2O3; however, the effect of NO was not as notable as SO2. The adsorption of arsenic is proposed to follow the Mars-Maessen mechanism. In relative low oxygen condition, the oxidation of arsenic was mainly relied on lattice oxygen of sorbent. Introduction of oxygen in flue gas could reoxidize the reduced oxide and therefore facilitate the arsenic capture. (C) 2016 Elsevier Ltd. All rights reserved.