Simultaneously boosting acetylene hydrochlorination activity and avoiding formation of explosive copper acetylide over Cu-based catalyst, which represented a promising alternative to Hg-based and noble metal catalysts, remained challenging. Herein, we fabricated a frustrated single-atom Cu/O Lewis pair catalyst (Cu/O-FLP) by coupling epoxide group (C–O–C) with atom-dispersed Cu-cis-N₂C₂Cl center to address this challenge. The basic epoxy site modulated the electron-deficient state of Lewis-acidic Cu center and paired with the Cu-cis-N₂C₂Cl moiety to preferentially break HCl into different electronegative Cu–Cl^δ− and C–O–H^δ+ intermediates, which further induced both an extra localized electric field to polarize acetylene and a upshift of the d-band center of catalyst, thereby promoting adsorption and enrichment of acetylene by enhancing the dipolar interaction between acetylene and active intermediates. Moreover, the generated Cu–Cl^δ− and C–O–H^δ+ drastically reduced the energy barrier of rate-limiting step and made vinyl chloride easier to desorb from the Lewis-basic oxygen-atom site rather than traditional Lewis-acidic Cu center. These superiorities ensured a higher activity of Cu/O-FLP compared with its counterparts. Meanwhile, preferential dissociation of HCl endowed single-atom Cu with the coordination-saturated configuration, which impeded formation of explosive copper acetylide by avoiding the direct interaction between Cu and acetylene, ensuring the intrinsic safety during catalysis.

In this work, SnO_x/activated carbon (AC) was synthesized by hydrothermal method, which was applied to acetylene hydrochlorination. Characterizations showed the SnO_x nanoparticles were uniformly dispersed on the carbon, with the co-existence of SnO and SnO₂. The acetylene conversion of SnO_x/AC was 75%, much higher than that of SnCl₄/AC. It was shown that the adsorption of reactants on SnO_x was stronger than on SnCl₄. Theoretical calculations showed the adsorption energies of reactants on SnO_x were thermodynamically favorable and suggested that Sn⁴⁺ and Sn²⁺ in SnO_x have different adsorption capacities for reactants. Through adjusting the valence ratio of SnO_x, SnO_x/AC O 4 h (O for oxidation) exhibited the best catalytic performance and had the strongest adsorption capacity for the reactants. However, the SnO_x/AC catalyst was easily deactivated during acetylene hydrochlorination due to the loss of Sn. The doping of N effectively reduced the loss of Sn and improved the stability of the catalyst due to the anchoring effect of N on the SnO_x particles.