Efficient capture of carbon dioxide to form organic crystals at low pressure and room temperature

Abstract

Carbon dioxide capture and storage (CCS) and carbon dioxide capture and utilization (CCU) are potential solutions for mitigating the greenhouse effect. Organic amines had been used for CCS. However, there are still scarce reports on the formation of solids after the capture of CO₂, especially in the crystalline form. This study explores a novel method for capturing and storing carbon dioxide using organic superbases 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and tetrahydropyrrole (Py) to form stable carbamate crystals DBU–Py–CO₂ at room temperature and low pressure. Interestingly, these crystals also exhibited exceptional stability when stored in a closed centrifuge tube at room temperature for over 500 days. The process involves a nucleophilic attack on CO₂ by an amino anion generated from these materials, forming well-ordered carbamate crystals as confirmed by single-crystal diffraction. The captured CO₂ can be reversibly released upon low dose heating. This approach presents promise for mitigating greenhouse gas emissions and utilizing CO₂ as a crystalline material without the need for metal catalysts or solvents.