Kazi Z. Sumon

Part 5b: Solvent chemistry: reaction kinetics of CO2 absorption into reactive amine solutions

Reaction kinetics is one of the most important parameters for the amine-based CO2 capture process because it indicates how fast CO2 reacts with amine, and it is one of the key parameters required for simulating and designing the absorption column. Reaction kinetics has been studied for several decades to aid the understanding of the reaction mechanism, obtaining the kinetics data and understanding the kinetics behavior. This article will comprehensively review these research activities from past to present and look at the future perspective of the study of CO2 absorption kinetics.

Part 5c: Solvent chemistry: solubility of CO2 in reactive solvents for post-combustion CO2

Concerns about climate change have propelled research efforts to develop affordable and environmentally benign technologies to capture CO2 from large emission sources, which can subsequently be used either for enhanced oil recovery or stored in other geological storage sites. The study of the solubility of CO2 in solvents is therefore of great interest, both from the theoretical and practical points of view. To screen solvents or to design CO2 capture processes, knowledge of the equilibrium solubility of CO2 in the solvents is necessary. A large body of solubility data of CO2 in aqueous and non-aqueous solutions of prominent industrial amines are available in literature. We present such data along with a description of the experimental techniques and thermodynamic models used. Innovations made to obtain an optimum solubility of CO2 and to minimize the energy cost of a desired CO2 capture system by adopting different kinds of solvents are also reviewed.

Molecular Dynamics Simulations of Proposed Intermediates in the CO2 + Aqueous Amine Reaction

Ab initio molecular dynamics simulations of up to 210 ps have been performed on various aqueous intermediates postulated in the CO2 + amine reaction, important for CO2 capture. Observations of spontaneous deprotonation of aqueous carbamate zwitterions R1R2NHCOO(±) by bulk water (instead of additional amine, or via umbrella sampling) are reported apparently for the first time. Carbamic acid structures R1R2NCOOH were observed in some simulations, arising from zwitterions not via classical 1,3-H-shifts but via Grotthuss-style multiple-H(+) transfer pathways that involve bulk H2O and require carbamate anions R1R2NCOO(-) as an intermediate stage along the way. H(+)-bridging complexes, including not only Zundel ions [water·H(+)·water](+) but neutral carbamate complexes [carbamate(-)·H(+)·water], were observed in simulation. These results should assist efforts in improving underlying mechanisms for kinetic modeling.