Amino acid salt solutions for carbon dioxide capture

Reactive absorption is a common process in the chemical industry and is used, among others, in the treatment of CO2 containing industrial gas streams. The current work was a part of a project with the aim to assess new reactive solvents based on amino acid salts for CO2 removal from industrial gas streams. Initially, a group of promising amino acid salts (taurine, sarcosine, L-proline, -alanine, 6-aminohexanoic acid and DL-methionine) was screened for their CO2 absorption kinetics, pKa values, CO2 effective capacity, precipitation window and identity of the precipitates. Based on the results of this study, the (alkaline salt) of imino acid L-proline was chosen for further investigation. For this solvent, important characteristics like physico-chemical properties, CO2 absorption kinetics, thermodynamic equilibria and energy consumption for a solvent regeneration (reboiler duty) were determined. The potential of L-proline and other (precipitating) amino acid salts solutions for CO2 capture and utilization is still not fully explored and deserves further consideration.