Why the Gas Uptake Behavior of Dry Salt Water Is Vastly Different above 279 K? A Dynamics-Controlled Process That Can Be Intensified by the Cooling Stimulation Method

JP Hou and W Zhou and XR Wang and DS Bai, JOURNAL OF PHYSICAL CHEMISTRY C, 122, 27360-27367 (2018).

DOI: 10.1021/acs.jpcc.8b07612

The effect of temperature on CO2 uptake behavior of dry salt water was investigated by kinetics measurements and molecular dynamics simulations. The gas uptake capacity was found to be dramatically decreased at 279 K by the direct cooling adsorption procedure. By means of simulations, it was realized that the orientation of water and the hydrogen bond network structure near the silica surface are sensitive to temperature. With the temperature decreased, the water layer becomes local-structured by forming more hydrogen bonds, facilitating the capture of CO2 by forming the hydrate precursor easily. The change of the structure is irreversible once the CO2 uptake process occurred; hence, the gas uptake can carry on continuously even if the temperature rises. A cooling stimulation procedure was found to efficiently trigger the gas uptake process at temperatures higher than 279 K. By using this method, gas adsorption can be induced because the energy barrier of nucleation is reduced. This technology can save a certain amount of energy that is used to maintain the low temperature. Therefore, it might be a potential industrial method for efficient gas storage.

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