Molecular dynamics simulation on the decomposition of type SII hydrogen hydrate and the performance of tetrahydrofuran as a stabiliser

Molecular dynamics simulation is used to study the decomposition and stability of SII hydrogen and hydrogen/tetrahydrofuran (THF) hydrates at 150 K, 220 K and 100 bar. The modelling of the microscopic decomposition process of hydrogen hydrate indicates that the decomposition of hydrogen hydrate is led by the diffusive behaviour of H(2) molecules. The hydrogen/THF hydrate presents higher stability, by comparing the distributions of the tetrahedral angle of H(2)O molecules, radial distribution functions of H(2)O molecules and mean square displacements or diffusion coefficients of H(2)O and H(2) molecules in hydrogen hydrate with those in hydrogen/THF hydrate. It is also found that the resistance of the diffusion behaviour of H(2)O and H(2) molecules can be enhanced by encaging THF molecules in the (5(12)6(4)) cavities. Additionally, the motion of THF molecules is restricted due to its high interaction energy barrier. Accordingly, THF, as a stabiliser, is helpful in increasing the stability of hydrogen hydrate.