Electrochemical detoxification and recovery of spent SCR catalyst by in-situ generated reactive oxygen species in alkaline media

Abstract

An environmental friendly electrochemical detoxification and recovery process is developed for the spent SCR catalysts disposal under alkaline condition. It is revealed that the spent V2O5-WO3/TiO2 catalyst is severely aggregated and poisoned by arsenic compounds. In this study, the efficient removal of arsenic is achieved by the electrochemical advanced oxidation processes (EAOPs) at surface-modified carbon felt cathode, where the HO2− and highly oxidative OH are in-situ generated from two-electron ORR and electro-Fenton-like reaction, respectively. The mechanism of electrochemical arsenic extraction is systematically illustrated by employing the ESR measurements, and vanadium species induced electro-Fenton-like reaction is proposed. After electro-oxidative dissolution, the crystal structure and original composition of the catalyst support (TiO2 and WO3) are well maintained for recycle or subsequently re-fabrication process. After dipping active component on the detoxified catalyst, the regenerated catalyst shows a comparable SCR catalytic activity with the fresh sample. The present electrochemical strategy provides a promising approach for the spent catalysts utilization and further understanding for the in-situ generated reactive oxygen species in alkaline media.