Integration of a diamine solvent based absorption and coal fly ash based mineralisation for CO2 sequestration

Abstract Our previous studies have revealed that diamines containing one primary amine group exhibit a superior kinetics while retaining their intrinsic high capacities towards CO 2 absorption when compared with monoethanolamine. However, these diamine absorbents typically suffer from high regeneration energy due to the inherent structural stability of the formed carbamate species. In an effort to overcome this challenge, we developed a new CO 2 sequestration process that integrates the CO 2 absorption by a diamine solvent and the diamine regeneration as well as CO 2 mineralization by CaO-rich fly ash. Herein, we found that CO 2 rich diamine solutions can be chemically regenerated by fly ash with the stable cyclic performance via the CO 2 absorption - mineralization experiments, and the CO 2 sequestration capacity of the fly ash used in this process dominated the amine regeneration performance. The FT-IR analysis of species in the solution along with the characterizations of fly ash via SEM, EDX and XRD revealed that fly ash was effective to regenerate a diamine - 1-(2-hydroxyethyl)-4-aminopiperidine (C4) by deprotonation of C4H + , meanwhile, the CaO component in fly ash can react with CO 2 in the C4 solution to produce the calcium carbonate precipitate. This approach presents a significant energy saving alternative to the traditional CO 2 desorption process.