RuCl3 anchored onto post-synthetic modification MIL-101(Cr)-NH2 as heterogeneous catalyst for hydrogenation of CO2 to formic acid

A series of efficient ruthenium chloride (RuCl₃)-anchored MOF catalysts, such as RuCl₃@MIL-101(Cr)-Sal, and RuCl₃@MIL-101(Cr)-DPPB, have been successfully synthesized by post-synthetic modification (PSM) of the terminal amino of MIL-101(Cr)-NH₂ with salicylaldehyde, 2-diphenylphosphinobenzaldehyde (DPPBde) and anchoring of Ru(III) ions. The stronger coordination electron donor interaction between Ru(III) ions and chelating groups in the RuCl₃@MIL-101(Cr)-DPPB enhances its catalytic performance for CO₂ hydrogenation to formic acid. The turnover number (TON) of formic acid was up to 831 in reaction time of 2 h with dimethyl sulfoxide (DMSO) and water (H₂O) as mixed solvent, trimethylamine (Et₃N) as organic base, and PPh₃ as electronic additive.