Manipulating micro-electric field and coordination-saturated site configuration boosted activity and safety of frustrated single-atom Cu/O Lewis pair for acetylene hydrochlorination

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-Clδ− and C-O-Hδ+ 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-Clδ− and C-O-Hδ+ 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.