Phase equilibrium measurements of structure II clathrate hydrates of hydrogen with various promoters

Phase equilibrium measurements of single and mixed organic clathrate hydrates with hydrogen were determined within a pressure range of 2.0–14.0 MPa. The organic compounds studied were furan, 2,5-dihydrofuran, tetrahydropyran, 1,3-dioxolane and cyclopentane. These organic compounds are known to form structure II clathrate hydrates with water. It was found that the addition of hydrogen to form a mixed clathrate hydrate increases the stability compared to the single organic clathrate hydrates. Moreover, the mixed clathrate hydrate also has a much higher stability compared to a pure hydrogen structure II clathrate hydrate. Therefore, the organic compounds act as promoter materials. The stabilities of the single and mixed organic clathrate hydrates with hydrogen showed the following trend in increasing order: 1,3-dioxolane < 2,5-dihydrofuran < tetrahydropyran < furan < cyclopentane, indicating that both size and geometry of the organic compound determine the stability of the clathrate hydrates.

► We report phase equilibrium measurements of organic clathrate hydrates with hydrogen.
► The organics studied are furan, 2,5-dihydrofuran, tetrahydropyran, 1,3-dioxolane and cyclopentane.
► The organics form structure II hydrates with water.
► The organics act as promoter materials in mixed clathrate hydrates with hydrogen.
► The size and geometry of the organic compound determine the stability of the clathrate hydrate.