Hydrate phase equilibrium data of mixed methane-tetrahydrofuran hydrates in saline water

Solidified natural gas (SNG) technology through clathrate hydrates formation has been considered a viable opportunity for large scale stationary methane/NG storage application. In this work, we report thermodynamic data on mixed methane (CH4)-tetrahydrofuran (THF) hydrates in pure water and in saline water. Hydrate phase equilibrium of mixed CH4-THF hydrates in presence/absence of NaCl (3.0 wt% or 0.87 mol%) were determined employing a high-pressure micro-differential scanning calorimeter. The stoichiometric amount of THF (5.56 mol%) was used in all the experiments which shifts the hydrate phase equilibrium conditions toward milder region (lower pressure and high temperature). We report that the presence of 0.87 mol% NaCl has no significant effect on the equilibrium conditions of mixed CH4-THF hydrates at low pressure (<1.2 MPa) for a temperature range of 285.9–290.5 K, however more deviation in equilibrium curves occurs at higher pressure (>2.0 MPa). Clausius–Clapeyron plot for the experimental results was employed to calculate the enthalpy of hydrate dissociation. The enthalpy of dissociation of the mixed CH4-THF hydrates in presence of 0.87 mol% NaCl was found to be in the range of 150–170 kJ/mol of gas.