The utilization of copper-based catalysts for converting by-product hydrogen chloride (HCl) into chlorine gas (Cl2) offers a promising method for efficient management of HCl waste gas. However, a significant challenge in this process lies in catalyst deactivation, primarily attributed to the loss of active component in the form of Cu-Cl. In this study, we synthesized a Cu2.4CeV0.5Ox catalyst that exhibited remarkable performance, achieving a space-time yield of 2.26 g Cl2/gcat*h with stable conversion efficiency at approximately 83 % maintained over 600 h. This level of stability represents a substantial improvement compared to previous studies of copper-based catalysts. In-situ DRFITS combined with ToF-SIMS confirms the reduction evolution of metal-Cl bonds. Additionally, ab-initio calculations elucidated that the rate-limiting step involves oxygen vacancy replenishment by O2 rather than Cl over CeO2 and CeVO4, thereby inhibiting Cu-Cl bond formation. This study introduces a novel approach for efficienct treatment of HCl waste gas, paving the way for its potential industrial application.