Selective leaching of V, W and recycling of TiO2 carrier from waste V2O5-WO3/TiO2 catalysts by mixed alkali liquor

Abstract

Recovery of selective catalytic reduction (SCR) denitrification catalysts is important to reduce costs and environmental pollution. To recover and reuse the metal resources in the waste V2O5 - WO3/TiO2 catalyst, a mixed alkaline leaching system of NH3·H2O and sodium compounds was used. The method keeps the carrier composition and structure unchanged while achieving the separation of V and W. The effects of three additives, NaOH, Na2CO3 and NaCl, were investigated after determining the optimum leaching concentration of NH3·H2O at 6.0 mol‧L−1. The results showed the most superior leaching efficiency of V and W in NH3·H2O - NaOH solution. Next, the effects of additive concentrations and process parameters on the leaching of V and W were systematically investigated. Under optimum leaching conditions, 77.47%V and 47.7%W were leached without destroying the carrier. Moreover, this method showed similar separation of valuable metals from different components of waste catalysts, demonstrating its versatility. Meanwhile, the TiO2 carriers with undamaged structure can be directly prepared as new denitrification catalysts. Finally, the comprehensive utilization of 92.84%W, 91.94%V and 92.17%Ti resources in the waste denitrification catalyst is realized. Overall, the method may be an environmentally friendly solution for resource recovery of waste SCR catalysts.