Recent advances in density functional theory and molecular dynamics simulation of mechanical, interfacial, and thermal properties of natural gas hydrates in Canada
S Mathews and S Daghash and A Rey and P Servio, CANADIAN JOURNAL OF CHEMICAL ENGINEERING, 100, 2557-2571 (2022).
Gas hydrates are inclusion compounds of a water backbone that encloses gaseous molecules. Thanks to their applications in gas recovery, carbon capture and storage, gas storage, and flow assurance, generating high quality data and predictions of their properties is paramount. A review of novel techniques using first principles density functional theory and molecular dynamics simulations methods coupled to auxiliary simulations methods is presented herein. Structure I (sI), structure II (sII), and structure H (sH) hydrates have been studied extensively, with studies of their material strength showing that it is often misleading to use the properties of ice instead of the difficult-to-determine gas hydrate properties. Key differences between the three structures and their possible guests are presented. The interfacial properties of gas hydrates display key behaviours that control nucleation and growth, which are important phases in controlling and monitoring their formation. Gas hydrate thermal properties are also examined, with key differences existing between guests and some unusual alignment in the cages shown for carbon dioxide, ethane, and ethylene oxide sI hydrates. First principles infrared spectroscopy is also examined, with techniques showing that these signatures can be tied to and predict material properties to improve the speed of analysis. Therefore, by quantifying, modelling, predicting, and explaining their formation and dissociation, and linking these to their thermal, material, and interfacial properties, a database of reliable data for science and engineering methods and applications is formed to provide a basis for further work.
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