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 (2-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. Results show that the SO2 promotes the arsenic removal of Fe2O3, CeLaO and FeCeLaO. At 400 ℃, the arsenic removal efficiencies of the three oxides increase from 45.3%, 72.5% and 81.3% without SO2 to 62.6%, 80.5% and 91.0%, respectively. The SO2 inhibits the arsenic removal of La2O2CO3 and FeLaO, and the inhibition effect is pronounced at high temperatures. The sulfur poisoning resistance of Si-Al carriers increases with the increase of Si/Al ratio. When the Si/Al ratio is increased to 9.74, the arsenic removal efficiency in the SO2 environment is 13.9% higher than that 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.