Integrated CO<sub>2</sub> Capture and Conversion to Methanol Leveraged by the Transfer Hydrogenation Approach
Abhishek Kumar, Ritu Bhardwaj, Joyanta Choudhury
Abstract
Catalytic transfer hydrogenation of chemically captured CO 2 toward MeOH production utilizing ethylene glycol as the hydride donor has been established under mild reaction conditions by employing a Ru(II)–CNN pincer catalyst (CNN = C NHC ^N pyridine ^N benzimidazole tridentate ligand) and a tertiary amine tetramethylethylenediamine (TMEDA). Through a cooperative action with ethylene glycol, TMEDA was found to be the most effective tertiary amine in this integrated CO 2 capture/conversion protocol to achieve as high as 64% of MeOH yield and up to 112 catalytic turnovers. Dilute CO 2 stream (10% in N 2 ) could also be utilized in this integrated protocol to provide ∼70% yield of MeOH. Involvement of Ru–H active species in the process, generated from the reaction of the catalyst with ethylene glycol, was traced via a spectroscopic investigation. Considering that ethylene glycol can be produced from a renewable bioresource (e.g., nonfood biomass), the developed CO 2 -to-MeOH transfer hydrogenation protocol integrated with a prior efficient CO 2 -capturing process represents a prospective approach complementary to the existing catalytic hydrogenation platforms which typically use fossil-derived H 2 gas under a high pressure setup.