Thermodynamic Stability of Mixed Gas Hydrates Containing Hydrogen

Phase equilibrium curves of H-2 + tetrahydrofuran and H-2 + tetra-n-butyl ammonium bromide mixed gas hydrates were measured. Each three-phase equilibrium curve converges at three-phase equilibrium point of pure tetrahydrofuran and tetra-n-butyl ammonium bromide hydrates, respectively. It is directly confirmed by use of Raman spectroscopy that H-2 is enclathrated in the hydrate cages by adding a small amount of tetrahydrofuran or tetra-n-butyl ammonium bromide. In both mixed gas hydrates, H-2 is selectively enclathrated in the small cage despite the concentrations of aqueous solution.