Ruthenium (Ru)-based catalysts have been candidates in hydrochlorination for vinyl chloride monomer (VCM) production, yet they are limited by efficient acetylene (C2H2) utilization. The strong adsorption performance of HCl can deactivate Ru active sites which resulted in weak C2H2 adsorption and slow activation kinetics. Herein, we designed a channel that employed metal-organic framework (MOF)-encaged Ru single atoms to achieve rapid adsorption and activation of C2H2. Low-Ru (∼0.5 wt %) single-atom catalysts (named Ru-NC@MIL) were assembled by hydrogen-bonding nanotraps (the H-C≡C-Hδ+···Oδ- interactions between C2H2 and carboxylate groups/furan rings). Results confirmed that C2H2 could easily enter the encapsulation channels in an optimal mode perpendicular to the channel with a potential energy of 42.3 kJ/mol. The harvested C2H2 molecules can be quickly passed to Ru-N4 active sites for activation by stretching the length of carbon-carbon triple bonds (C≡C) to 1.212 Å. Such a strategy guaranteed >99% C2H2 conversion efficiency and >99% VCM selectivity. Moreover, a stable long-term (>150 h) catalysis with high efficiency (∼0.85 kgvcm/h/kgcat.) and a low deactivation constant (0.001 h-1) was also achieved. This work provides an innovative strategy for precise C2H2 adsorption and activation and guidance for designing multi-functional Ru-based catalysts.
Keywords: Ru single atoms; acetylene hydrochlorination; channel engineering; hydrogen-bonding nanotraps; metal−organic frameworks.