Computational Chemistry Study of Molecular Interactions in CO2-loaded Diethylene Glycol, Triethylene Glycol, and Diethylene Glycol Dimethyl Ether

CO2 physical absorption has great potential for greenhouse gas mitigation. CO2 physical absorption mechanisms at the atomistic level were investigated by evaluating the correlations between molecular diffusions and molecular interactions using molecular dynamics (MD) simulations for three types of CO2 loaded absorbents: diethylene glycol (DEG), triethylene glycol (TEG), and diethylene glycol dimethyl ether (DEGDME). The diffusion coefficient of DEGDME was about one order of magnitude greater than those of DEG and TEG. The radial distribution functions between CO2 molecules and solvent molecules and those between solvent molecules suggested that the interactions between the solvent molecules were significant in CO2-loaded DEG and TEG solvents, whereas the interactions between the CO2 and solvent molecules were dominant in the CO2-loaded DEGDME solvent. The difference in the molecular interactions was correlated with the absolute values of the calculated diffusivities. MD calculations are a powerful tool to investigate CO2 physical absorption mechanisms at the atomistic level.