Recovery of spent SCR denitration catalyst: A review and recent advances

NOx is a common air pollutant that can cause a variety of problems including environmental pollution and human illness. Selective catalytic reduction (SCR) is currently the most effective method for treating NOx, and SCR denitration catalysts are widely used in coal-fired power plants, steel industry, automotive exhaust gas, etc. SCR denitration catalyst must be recovered if it becomes inactive and cannot be regenerated. The spent SCR denitration catalyst contains vanadium, tungsten, titanium and other valuable metals, and its recovery has important economic and environmental benefits. The current recovery methods for spent oxide SCR denitration catalysts are divided into two main categories: hydrometallurgy and pyrometallurgy. Hydrometallurgical recovery mainly includes reductive acid leaching and alkaline pressure leaching, while pyrometallurgical recovery mainly includes Na2CO3 roasting and composite roasting. Both methods have their own advantages and disadvantages. In their application, hydrometallurgical recovery needs to improve the metal leaching ratio and expand metal recovery types, while pyrometallurgical recovery needs to reduce process energy consumption and secondary pollution. Among them, vanadium is easier to extract, while the selective extraction of tungsten is more difficult, and titanium is basically left in the slag and then purified, so full element recovery based on current technology is more challenging. This paper reviews the recent research progress on spent oxide SCR denitration catalyst recovery, introduces the reaction mechanism and technical problems involved in each recovery process, and points out that multi-technology synergistic treatment and high value-added product preparation are the future development directions for spent oxide SCR denitration catalyst recovery.