Facilitating guest transport in clathrate hydrates by tuning guest-host interactions

  1. Get@NRC: Facilitating guest transport in clathrate hydrates by tuning guest-host interactions (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1063/1.4907720
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Journal titleJournal of Chemical Physics
Article number74705
SubjectBonding; Crystal structure; Digital storage; Gas hydrates; Hydration; Hydrogen bonds; Molecular dynamics; Molecules; Natural gas; Natural gas well production; Nuclear magnetic resonance; Nuclear magnetic resonance spectroscopy; Organic solvents; Single crystals; Synthesis (chemical); Water injection; X ray diffraction; 2D exchange spectroscopy; Direct observations; Guest-host interactions; Hydrogen bonding interactions; Molecular dynamics simulations; Natural-gas production; Nuclear magnetic resonance(NMR); Single crystal x-ray diffraction; Carbon dioxide
AbstractThe understanding and eventual control of guest molecule transport in gas hydrates is of central importance for the efficient synthesis and processing of these materials for applications in the storage, separation, and sequestration of gases and natural gas production. Previously, some links have been established between dynamics of the host water molecules and guest-host hydrogen bonding interactions, but direct observation of transport in the form of cage-to-cage guest diffusion is still lacking. Recent calculations have suggested that pairs of different guest molecules in neighboring cages can affect guest-host hydrogen bonding and, therefore, defect injection and water lattice motions. We have chosen two sets of hydrate guest pairs, tetrahydrofuran (THF)-CO2 and isobutane-CO2, that are predicted to enhance or to diminish guest-host hydrogen bonding interactions as compared to those in pure CO2 hydrate and we have studied guest dynamics in each using 13C nuclear magnetic resonance (NMR) methods. In addition, we have obtained the crystal structure of the THF-CO2 sII hydrate using the combined single crystal X-ray diffraction and 13C NMR powder pattern data and have performed molecular dynamics-simulation of the CO2 dynamics. The NMR powder line shape studies confirm the enhanced and delayed dynamics for the THF and isobutane containing hydrates, respectively, as compared to those in the CO2 hydrate. In addition, from line shape studies and 2D exchange spectroscopy NMR, we observe cage-to-cage exchange of CO2 molecules in the THF-CO2 hydrate, but not in the other hydrates studied. We conclude that the relatively rapid intercage guest dynamics are the result of synergistic guest A-host water-guest B interactions, thus allowing tuning of the guest transport properties in the hydrates by choice of the appropriate guest molecules. Our experimental value for inter-cage hopping is slower by a factor of 106 than a published calculated value.
Publication date
PublisherAIP Publishing
AffiliationMeasurement Science and Standards; National Research Council Canada; Security and Disruptive Technologies
Peer reviewedYes
NPARC number21275649
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Record identifierbf57fefb-ba95-4f29-a88a-c0fcb07c12a8
Record created2015-07-14
Record modified2017-03-23
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