New liquid absorbents for the removal of CO₂ from gas mixtures

New liquid absorbents (LA) consisting of water solutions of CO₂-complexing agents have been developed and tested in an experimental lab-scale to be used in CO₂ separation from gas mixtures. The results here presented concern the preparation of these amino acid based new liquid absorbents and the studies carried out to determine their performance as CO₂ scrubbers. The novel systems show good performance in terms of sorption and stability compared to the standard alkanolamines. Moreover, the experimental results have shown that among the studied carriers, arginine and ornithine are the natural amino acids with greater affinity towards CO₂ and that some of the here synthesized amino acids show outstanding absorption capacities, superior to MEA or any other amino acid tested. The developed materials have a direct use as mobile carrier membranes for facilitated transport and present a great potential for application in gas separation processes. Computational (DFT) and spectroscopic (¹H and ¹³C-NMR) methods have been applied to make clear the mechanism of carbamate formation from the amine group of amino acids and CO₂.