Single-stage Coextraction and Costripping for Efficient Resource Recycling and Regeneration of Spent SCR Catalysts

Abstract Spent V-Ti-based selective catalytic reduction (SCR) denitrification catalysts are classified as hazardous solid wastes containing critical vanadium (V), molybdenum (Mo), and tungsten (W). However, traditional separation and recovery strategies require massive acid inputs and complicated multistep operations, restricting environmentally friendly industrial application. Herein, this work reports a one-pot integrated single-stage coextraction and costripping method to efficiently recycle V, Mo, and W from alkaline leachate of waste SCR catalysts. Preacidified primary amine N1923 achieves simultaneous extraction of three target metals, and subsequent ammonia stripping generates corresponding ammonium oxyacid solutions. Under optimal operational conditions, single-cycle total recoveries reach 94.96% for V, 83.50% for Mo, and 91.53% for W. The stripping liquor together with leaching residues can be applied to synthesize fresh SCR catalysts via impregnation with denitrification efficiency exceeding 92%, forming a renewable regeneration route. Saturation loading tests, slope analysis, and spectroscopic characterizations confirm an anion-exchange extraction mechanism. With reduced acid consumption and high metal recovery efficiencies, this approach provides a sustainable pathway for resource valorization of spent SCR catalysts.