Janus-Ligand-Engineered High-Performance Single-Atom Ru Catalyst for Acetylene Hydrochlorination

While the lower activation energy endows ruthenium (Ru)-based catalysts with efficient catalytic centers, which are widely explored in mercury-free acetylene hydrochlorination, quantitative electronic and geometric structure–activity relationships remain poorly understood. Herein, inspired by Janus with double-faced properties, a set of single-atom Ru-based catalysts coordinated with Janus ligand R1C═ON(R2)2 is employed to investigate the electronic and geometric structure–activity relationships. By systematically regulating the length of R1 and R2 in R1C═ON(R2)2, a separate linear electronic and geometric structure–activity relationship is revealed, showing that a higher electron density or smaller steric hindrance would help to improve catalytic performance. As a result, Ru-(H)L(i-C3)2/AC catalysts, prepared from 0.2 wt % Ru and (H)L(i-C3)2 ligand, with the highest electron density and smallest steric effect exhibit the highest activity. The Janus ligand regulation strategy identifies quantitative electronic and geometric structure–activity relationships of Ru-based catalysts. It provides detailed insights for advancing the rational design of high-performance catalysts for acetylene hydrochlorination.