Investigating the Thermodynamic Stabilities of Hydrogen and Methane Binary Gas Hydrates

When hydrogen (H 2 ) is mixed with small amounts of methane (CH 4 ), the conditions required for clathrate hydrate formation can be significantly reduced when compared to that of simple H 2 hydrate. With growing demand for CH 4 as a commercially viable source of energy, H 2 + CH 4 binary hydrates may be more appealing than extensively studied H 2 + tetrahydrofuran (THF) hydrates from an energy density standpoint. Using Raman spectroscopic and powder X-ray diffraction measurements, we show that hydrate structure and storage capacities of H 2 + CH 4 mixed hydrates are largely dependent on the composition of the initial gas mixture, total system pressure, and formation period. In some cases, H 2 + CH 4 hydrate kinetically forms structure I first, even though the thermodynamically stable phase is structure II.