In situ hydrogenation of captured CO₂ to formate with polyethyleneimine and Rh/monophosphine system

CO₂ in the air can be efficiently captured with simultaneous activation by PEI (polyethyleneimine) to form ammonium carbamate and/or carbonate species. Thus, the in situ hydrogenation of captured CO₂ into energy-storage materials rather than going through the desorption of conventional CCS (carbon capture and storage) runs better in comparison with equivalent gaseous CO₂, thus validating this potential application of CCU (carbon capture and utilization) for supplying renewable energy. PEI ₆₀₀ as an effective carbon absorbent in this study could also be assumed to serve as both ligand and base to promote the catalytic hydrogenation of captured CO₂, consequently acting as a 'hinge base' to combine capture and hydrogenation processes. The pathway was studied by NMR and in situ FT-IR spectroscopy under CO₂ pressure. This protocol could open up great potential in transforming the captured CO₂ from waste to fuel-related products.