Kinetic considerations and formation rate for carbon dioxide hydrate, formed in presence of a natural silica-based porous medium: How initial thermodynamic conditions may modify the process kinetic

Carbon dioxide hydrate was produced in presence of a silica-based natural sand, coming from the Mediterranean seafloor. Tests were carried out with the same initial conditions, except for pressure, which was about 30 bar for half of them, while it was close to 40 bar in the others. Pressure-temperature values were compared with equilibrium data present elsewhere in literature. It was established that the porous medium acted as kinetic inhibitor, while its influence on thermodynamic properties was negligible. The hydrate formation rate was evaluated along the whole tests and was used to confirm the different behaviors of the two groups of tests under the kinetic point of view. It also allowed to well distinguish hydrate nucleation from the massive growth phase. Values produced during experiments were compared with data taken from literature and a strong correlation was observed. Finally, moles of hydrate formed over time was measured and proved that, in tests having a higher initial pressure, massive hydrate growth occurred immediately, while in other tests it appeared delayed over time.