In situ dynamic modulation of zero-valent and low-valent copper ratio for constructing stable copper catalysts for...

Regulating the dynamic evolution of active sites is key to improving the stability of Cu-based catalysts for acetylene hydrochlorination. Herein, we report a strategy to boost catalytic stability by in-situ tuning the Cu⁰/Cu^δ+ dual-site ratio. Using copper oxalate as a precursor, the 10% CuC₂O₄/AC-900 catalyst is prepared via carbothermal reduction. By controlling HCl-activation time, the surface chemical state of Cu species can be finely modulated to construct an optimal Cu⁰/Cu^δ+ pair. Activation for 40 min yields excellent reaction stability, as it optimizes the concentration of active Cu^δ+ species and establishes a dynamic balance between activity and stability. Additionally, we propose a hydrogen-assisted stabilization mechanism: introducing trace H₂ into the reaction atmosphere prevents deep chlorination and deactivation of Cu sites, stabilizes the Cu⁰/Cu^δ+ dual-site structure, and significantly prolongs catalyst lifetime. This work deepens fundamental understanding of active sites in acetylene hydrochlorination and provides theoretical insights and practical guidelines for designing stable mercury-free catalysts.