30. Deactivation of V₂O₅–WO₃–TiO₂ SCR Catalyst by HF During Co-Firing Electrolytic Aluminum Waste with Coal

Fluorine-containing waste from the electrolytic aluminum industry would cause environmental pollutions if the waste is improperly disposed. It is important and urgent to develop a harmless treatment method for the waste. In this paper, co-firing electrolytic aluminum waste with coal was studied. And the deactivation of V₂O₅–WO₃–TiO₂ SCR catalyst by HF was investigated by a lab-scale experimental system. The results show that HF is harmful to the catalyst. The denitrification efficiency of catalyst sample which treated by flue gas with HF is reduced. The denitrification efficiency of sample increases with increasing work temperature and deactivation temperature. When the work temperature is 400 °C, the denitrification efficiency of catalyst sample is higher than 90%. Analysis by temperature programmed desorption of ammonia (NH₃-TPD), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) show the definite dispersion of F on the surface of SCR catalysts. HF would lead to decrease specific surface areas, surface acidity, and oxidation–reduction ability. Although the concentrations of O_β (surface adsorbed oxygen) increases owing to HF, which may interact with TiO₂ to destroy the carrier structure. Meanwhile, there is a chemical deactivation for the influence of HF on V₂O₅ and WO₃.