High resistance SO2 adsorbent of Fe-Ce-La oxides @ Si-Al carrier for arsenic capture from middle-low-temperature flue gas

It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions (<400 ℃). In this paper, five Fe-Ce-La oxides were prepared by co-precipitation method and FeCeLaO/SiO2-Al2O3 composite adsorbents were prepared by coupling fly ash-based Si-Al carriers. The active components Fe-Ce-La oxides and Si-Al carriers were characterized by TPD, TG, XRF, BET, and XPS, respectively. The effects of temperature, Si/Al ratio, and FeCeLaO loading rate on the sulfur resistance were investigated. The results showed that SO2 promoted the arsenic removal of Fe2O3, CeLaO, and FeCeLaO. At 400 ℃, the arsenic removal efficiency of the three increased from 45.3 %, 72.5 % and 81.3 % without SO2 to 62.6 %, 80.5 % and 91.0 %, respectively. SO2 inhibits the arsenic removal of La2O2CO3 and FeLaO, and the higher the temperature, the stronger the inhibition. The sulfur poisoning resistance of Si-Al carriers increased with the increase of Si/Al ratio. When the Si/Al ratio increases to 9.74, the arsenic removal efficiency in the SO2 environment is 13.9 % higher than in the absence of SO2. Introducing FeCeLaO active components is beneficial for enhancing the SO2 poisoning resistance of Si-Al carriers. The strong sulfur resistance of the FeCeLaO/SiO2-Al2O3 composite adsorbent results from multiple factors: protective effects of Ce on Fe, La, and Al; sulfation-induced generation of Ce3+ and surface-adsorbed oxygen; and strong surface acidity of SiO2.