Molecular behavior of guest molecules in clathrate hydrates by ab initio molecular dynamics simulations

摘要

Clathrate hydrates are ice-like crystal formed by hydrogen-bonded water molecules and contain guest molecules such as methane and carbon dioxide.The guest molecules are usually enclosed one by one in the cages formed by the water molecules.Since it has gas selectivity at the time of incorporation and the phase equilibrium condition can be controlled by the type of guest molecule,various applications are considered as gas storage,separation,and cooling mediums.The clathrate hydrate formation conditions and gas inclusion properties are determined by the interaction between the guest molecule and the host water molecule.Natural gas hydrate contains hydrophobic molecules such as methane and propane,and the hydrophobic interaction between guest and host is significant.On the other hand,semi-clathrate hydrate,which is expected to be a kind of phase change heat storage medium in recent years,is considered to have a hydrogen bond between the ionic guest and the host.Such strong interactions greatly affect phase equilibrium conditions and structural stability.