Efficient recovery of scrapped V2O5-WO3/TiO2 SCR catalyst by cleaner hydrometalurgical process

摘要

China generates a large number of scrapped selective catalytic reduction (SCR) catalysts in the fossil fuel combustion plants every year. As a result, there is a giant quantity of 5 x 10(5)t scrapped V2O5-WO3/TiO2 SCR catalyst annually worldwide, in which arsenic poisoning is a major cause of catalysts deactivation. In this study, a novel cleaner recovery process of alkaline-acid stepwise leaching was proposed for the high-arsenic scrapped SCR catalysts to achieve excellent arsenic removal and structural reforming. It is found that arsenic can be completely removed from 1.92% to below the detection limit, and the surface area of regenerated catalysts is restored to 31 m(2)/g (similar to that of commercial catalysts). In the subsequent pickling and regeneration, Na+ can be eliminated to obtain anatase-type TiO2 for further activity recovery. Besides, valuable elements (W, V) have been successfully recycled by leaching the As-containing solid waste with ammonium salt. After replenishing active components, regenerated catalyst exhibits comparable activity with the commercial fresh catalyst, offering a promising method for scrapped catalyst recovery and further understanding of cleaner produces for waste management.