Relationship between Diffusion and Chemical Exchange in Mixtures of Carbon Dioxide and an Amine-Functionalized Ionic Liquid by High Field NMR and Kinetic Monte Carlo Simulations.

NMR exchange spectroscopy (EXSY) and NMR diffusion spectroscopy (PFG NMR) were applied in combination with kinetic Monte Carlo (MC) simulations to investigate self-diffusion in a mixture of carbon dioxide and an amine-functionalized ionic liquid under conditions of an exchange of carbon dioxide molecules between the reacted and unreacted states in the mixture. EXSY studies enabled residence times of carbon dioxide molecules to be obtained in the two states, whereas PFG NMR revealed time-dependent effective diffusivities for diffusion times comparable with and larger than the residence times. Analytical treatment of the PFG NMR attenuation curves as well as fitting of the PFG NMR effective diffusivities by KMC simulations enabled determination of diffusivities of carbon dioxide in the reacted and unreacted states.

Combined application of high-field diffusion NMR and molecular dynamics simulations to study dynamics in a mixture of carbon dioxide and an imidazolium-based ionic liquid.

Self-diffusion and related short-time dynamic and structural properties were investigated for mixtures of carbon dioxide and the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [bmim](+)[Tf2N](-) for a broad range of carbon dioxide molar fractions and at different temperatures. The studies were performed by a novel multinuclear pulsed field gradient (PFG) NMR technique, which combines the advantages of a high magnetic field (17.6 T) and a high magnetic field gradient (up to 30 T/m), in combination with molecular dynamics simulations.