Combined theoretical and experimental studies on CO2 capture by amine-activated glycerol

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2021-03, Vol.408, p.128002, Article 128002
• Main Authors: Furtado, Isabelle O., dos Santos, Thiago C., Vasconcelos, Larissa F., Costa, Luciano T., Fiorot, Rodolfo G., Ronconi, Célia M., Carneiro, José Walkimar de M.
• Format: Article
• Language: English
• Subjects: CO2 capture; DFT calculation; Glycerol; Glycerol activation; Organic carbonates; Triethylamine
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.128002

[Display omitted] •DFT calculations predict formation of carbonates from glycerol reacting with CO2.•Tertiary alkylamines may activate glycerol for reaction with CO2.•Intermolecular hydrogen bond increases glycerol nucleophilicity.•FTIR and 13C NMR and 1H–13C HMBC spectra suggest formation of organic carbonate. Although CO2 capture by alkanolamine aqueous solutions is a well-established technology, it demands high energy penalties and water consumption. Therefore, the development of new methods for CO2 removal is still a challenge. Herein, we employed the Density Functional Theory (DFT) to explore the potential of different mixtures composed of glycerol and nitrogen-containing bases to capture CO2. By combining glycerol, CO2 and the bases, it was possible to show that aliphatic amines are able to form intermolecular hydrogen bonds with the primary hydroxyl groups of glycerol, increasing their nucleophilicity and assisting the reaction with CO2 to form glycerol carbonate as the most stable product. To confirm that glycerol carbonate would be experimentally obtained from the given mixture, we selected triethylamine (TEA) to assist glycerol (Gly) in its reaction with CO2. The resulting product was characterized by Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), 1D and 2D Nuclear Magnetic Resonance spectroscopy (1H and 13C NMR) and Thermogravimetric Analysis (TGA). The ATR-FTIR results showed that TEA is protonated after bubbling CO2 in the glycerol/TEA mixture, suggesting that the reaction with CO2 occurs after deprotonation of glycerol, forming organic carbonates, as also indicated in the NMR spectra. The combined theoretical and experimental results indicate that TEA is able to activate glycerol in its reaction with CO2 to form organic carbonates, being an alternative procedure for CO2 capture.