Comprehensive recovery of W, V, and Ti from spent selective reduction catalysts
Liwen Ma, Xiaoli Xi, Jiapeng Chen, Fan Guo, Zijie Yang, Zuo‐Ren Nie
Abstract
Abstract In this study, spent WO 3 /V 2 O 5 ‐TiO 2 catalysts used for selective catalytic reduction were treated by a hydrometallurgical process to comprehensively recover valuable metallic elements, such as W, V, and Ti. Al and Si impurities were preferentially removed by selective microwave‐assisted alkali leaching. W and V were leached by enhanced high‐pressure leaching with efficiencies estimated at 95% and 81%. The leaching of W and V followed the nuclear shrinkage model controlled by the combination of product layer diffusion and interfacial chemical reaction. A synergistic extraction was applied to separate W and V using an extractant mixture of di‐(2‐ethylhexyl)phosphoric acid P204 and the primary amine N1923. The extraction efficiencies of V and W reached 86.5% and 6.3%, respectively, with a separation coefficient (V/W) of 95.30. The product was precipitated after extraction to yield ammonium paratungstate (APT) and NH 4 VO 3 . The TiO 2 catalyst carrier residue meets commercial specifications for reuse. This comprehensive recovery process with the characteristics of high‐pressure leaching and synergistic extraction realizes the resourceful utilization of the spent catalysts.