In-Furnace Control of Arsenic Vapor Emissions Using Fe₂O₃ Microspheres with Good Sintering Resistance

The addition of Fe₂O₃ into furnaces is a promising method for arsenic pollution control. Nevertheless, Fe₂O₃ particles undergo serious sintering under actual furnace temperatures. To improve its sintering resistance, Fe₂O₃ hollow microspheres were synthesized by the template method and were tested in flue gas containing SO₂ and NO in the range of 1000-1300 °C. The results demonstrated that the amount of arsenic captured could be steadily maintained above 5 mg/g throughout the operating temperature range, and Fe₂O₃ microspheres could maintain the originally developed pore structure and hollow morphology well even at 1200 °C. Based on product analysis and density functional theory calculations, the fixation pathway of arsenic was proposed. In no oxygen conditions, As₂O₃ was first bound to the Fe₂O₃ surface by forming an -O-As-O-Fe stable structure and then was oxidized by lattice oxygen. The introduction of O₂ could regenerate the consumed lattice oxygen and therefore promote arsenic capture. Finally, the oxidized arsenic was fixed in products in the form of FeAsO₄. Additionally, the impact of acid gases was also investigated. SO₂ showed a notable inhibiting effect on arsenic capture, while the impact of NO was less noticeable.