Catalytic hydrogenation of CO2 to formate by heterogenized Ru(III) catalyst and computational investigation of strong promoting effect with triethylamine

[Display omitted] •Heterogenized molecular catalyst RuCl3@PY-CTF is applied to CO2 hydrogenation to formate.•RuCl3@PY-CTF exhibits favorable catalytic activity and excellent stability.•The effects of various organic bases on the hydrogenation of CO2 are compared.•The role of organic bases especially triethylamine is elaborated by DFT calculation. The Heterogenized Ru (III) catalyst is synthesized via immobilizing molecular RuCl3 on a pyridine-functionalized covalent triazine framework (PY-CTF). The N sites in the PY-CTF support effectively donate electrons to the Ru (III), resulting in a catalyst with favorable catalytic activity. The as-synthesized RuCl3@PY-CTF catalyst exhibits a high turnover number (TON) of 2067 in 2 h for the hydrogenation of CO2 to formate. In this reaction, triethylamine (TEA), tripropylamine (TPA), and triethanolamine (TEOA) are respectively employed as basic mediums. Among them, TEA demonstrates the highest promoting effect due to its greater contribution to the cleavage of H2, optimal interaction with CO2, and higher polarity of the HTEA-HCOO adduct, as determined by density functional theory (DFT) calculations.