Stability and dissociation studies of CO2 hydrate under different systems using molecular dynamic simulations

A precise estimation of hydrate stability and dissociation characteristics is needed for gas hydrate application. The present work monitored the stability and dissociation of CO2 hydrate under several simulation conditions with different molecular model, ensemble, system size and interface by employing molecular dynamic simulations. The hydrate stability was measured with four water molecular models and two carbon dioxide molecular models and we found the interaction of water-water and water-guest plays a great role compared to carbon dioxide with the stability order as: TIP4P/Ice > TIP4P/2005 > SPC/E > SPC/Fw. The decomposition phenomenon of host and guest molecular as well as the Arrhenius-type dependence of the decomposition rate and temperature with the activation energy of 18.48 +/- 0.4 5 kJ/mol is described. The dissociation rate between different interface of gas-hydrate and liquid-hydrate at different simulation time is compared and the mechanism is analyzed with the result that the difference increased first and then decreased (three stages of 13.2%, 52.6% and 26.9%) due to the mass transfer resistance. (C) 2021 Published by Elsevier B.V.