Integrated Carbon Dioxide Capture and Conversion to Methanol Utilizing Tertiary Amines over a Heterogenous...

Increasing carbon dioxide emissions has sparked a growing interest in capturing these emissions at the source of their release. For such processes, amines can be used as carbon dioxide capture agents. Herein, CO₂ was captured under ambient conditions using solutions of amines and polyamines in ethylene glycol. The captured solutions were then successfully hydrogenated to methanol under hydrogen pressure with a heterogeneous Cu/ZnO/Al₂O₃ industrial catalyst. An extensive amine scope found that tetramethyl-1,6-hexanediamine, with two tertiary amine sites, provided the highest methanol productivity. This reaction was then optimized to achieve up to 89% methanol yield under relatively mild conditions of 250 °C and 80 bar H₂ pressure. The catalyst was shown to be recyclable over five reaction cycles.