Extraordinary deactivation offset effect of zinc and arsenic on VO -WO/TiO catalysts: Like cures like.

The commercial VO -WO/TiO (VWTi) catalysts often suffer from a serious joint deactivation by multiple heavy metals in the flue gas for NO removal by NH-SCR. Herein, we report an extraordinary deactivation offset effect between Zn and As on VWTi with alleviation of the toxic effects of the heavy metals by "like cures like". With the As&Zn content of 4 wt%, VWTi-As&Zn exhibited over 97% NO conversion under a GHSV of 100,000 h and good SO/HO tolerance (> 93% NO conversion). It's presented 85% of fresh VWTi, exceeding those of VWTi-Zn (15%) by 5.6-fold and VWTi-As (70%) by 1.2-fold. Structure analysis showed that, unlike VWTi-As and VWTi-Zn, the VO vibration and dispersion state of VO sites over VWTi-As&Zn were hardly affected. Moreover, VWTi-As&Zn possessed both the Lewis and Brønsted acid sites while VWTi-Zn and VWTi-As had only one type of them. The operando infrared/Raman/UV-vis spectroscopy and DFT calculations verified that the less affected VO sites mainly reflected in three aspects: 1) the electron interaction between As and Zn; 2) the active VO Lewis acid sites; 3) lower energy barrier for N - H bond breaking. The "like cures like" phenomenon may open up an innovative pathway for the control of hazardous heavy metals.