Hydrogenation of CO2 to formate catalyzed by a Ru catalyst supported on a copolymerized porous organic polymer

Abstract

The catalytic hydrogenation of carbon dioxide to formate is of great interest due to its significant role in CO₂ utilization. In this study, a novel heterogeneous Ru(III) catalyst was prepared by immobilizing RuCl₃ on a porous organic polymer (POP) obtained from 1,4-phthalaldehyde (PTA) and 4,4′-biphenyldicarboxaldehyde (BPDA) with melamine. A copolymerization strategy utilizing monomers of varying lengths was employed to prepare the POP-supported Ru catalyst with adjustable porosity. The optimization of the framework porosity resulted in enhanced CO₂ affinity, accelerated mass transfer, and a remarkable enhancement in catalytic activity. A high turnover number (TON) of 2458 was achieved for the CO₂ hydrogenation to formate in 2 h with catalyst Cat-3 under 3 MPa (CO₂/H₂ = 1 : 1) at 120 °C in 1 M Et₃N aqueous solution. Moreover, the Cat-3 demonstrated good recyclability and was able to be reused for five consecutive runs, resulting in a high total TON of 9971.