Equilibrium Conditions of Binary Gas Mixture CH4 + H2 in Semiclathrate Hydrates of Tetra-n-butyl Ammonium Bromide

The thermodynamic equilibrium conditions for binary gas mixtures of CH4 and H-2 in the presence of TBAB were measured using the T-cycle method in this study. The experiments were conducted in the temperature range from (282.37 to 296.45) K and the pressure range from (0.46 to 15.47) MPa. The mole fraction of H-2 in gas mixtures varied from 0.15 to 0.85. The mass fraction of TBAB solution ranged from 0.10 to 0.50. The experimental results showed that the addition of TBAB can dramatically reduce the pressure required for hydrate formation at a fixed temperature. The equilibrium pressure increased along with the increasing composition of H-2 in the gas mixture. In order to gain a better understanding on the impact of TBAB on the thermodynamic equilibrium conditions for binary gas mixtures, a comparison was made between our data and phase equilibrium conditions for THF hydrates formed from the same gas mixture. The results showed that the thermodynamic promoting effect of TBAB was superior to that of THF when the temperature was below 284 K.