Revealing the potassium poisoning mechanism of V2O5-MoO3/TiO2 catalyst for chlorobenzene catalytic oxidation

Abstract

Commercial V₂O₅-MoO₃/TiO₂ (VMoTi) catalyst has been reported to present efficient VOCs removal ability via catalytic oxidation technology. However, it is susceptible to be poisoned by the alkali metals in flue gas, ultimately leading to the catalyst deactivation. This work selected potassium (K) species as the probe species to investigate the VMoTi deactivation mechanism for chlorobenzene (CB) catalytic oxidation. Results showed that K species deposition on VMoTi catalyst significantly inhibited the CB catalytic oxidation. While the fresh VMoTi catalyst achieved a CB conversion efficiency of nearly 100 % at 300–450 °C, this efficiency dropped to below 20 % with 2 wt% K₂O deposition. K species deposition decreased both the specific area and redox property of VMoTi catalyst, and it could also reduce the active sites on catalyst surface. Specially, the deposited K atom tended to destroy the initial V=O active site to form V-O-K species. Moreover, the deposition of K species triggered the electron transfer from V/Mo to O atoms, thereby strengthening the interactions among different species. It caused the vanadium species aggregation on catalyst surface, exerting a detrimental impact on CB catalytic oxidation. The work devotes to reveal the deactivation mechanism of commercial vanadium-based catalyst in industrial application, doing help on the VOCs emission control.