Synergistic Enhancement of Hydrolysis–Oxidation Drives Efficient Catalytic Elimination of Chlorinated Aromatics over VO x /TiO 2 Catalysts at Low Temperature

The efficient catalytic elimination of toxic chlorinated aromatics (i.e., dioxins, chlorobenzenes, etc.) at low temperature is still a great challenge. Based on the VO x /TiO 2 catalyst, a hydrolysis-oxidation strategy (CeO x and WO x doping) was built for desirable low-temperature catalytic activity, product selectivity, H 2 O tolerance, and chlorine desorption. The in situ and ex situ experimental characterizations and density functional theory calculations revealed that hydrolysis sites favored molecular adsorption, C–Cl cleavage, and HCl formation; meanwhile, oxidation sites enhanced the activation of reactive oxygen species and improved oxygen mobility and redox properties. The enhanced oxygen storage/release capacity (33–53 fold) and extended redox cycle (e.g., from V 5+ ↔V 4+ to V 5+ ↔V 4+ ↔V 3+ ) favored the deep oxidation. The introduction of H 2 O triggered the hydrolysis–oxidation process that promoted the catalytic activity and chlorine desorption due to the elevated generation of ·O 2 – and higher-activity ·OH. Furthermore, the water resistance of the VO x /TiO 2 -based catalyst was enhanced after the application of the hydrolysis–oxidation strategy. The V–Ce–W/Ti catalyst exhibited remarkable removal efficiency of dioxins (96.7–98.2%), which was reduced from 0.34–0.48 ng I-TEQ Nm –3 to 0.006–0.016 ng I-TEQ Nm –3 during pilot tests at 160–180 °C, achieving ultralow emissions. This work provides practical guidance for industry development for efficiently eliminating chlorinated organics in flue gas.