2-3-1 ゲストガスの硫化水素が天然ガスハイドレートの水和数の推定に及ぼす影響

抄録

Natural gas hydrate beneath the sea floor is expected as energy resources. Hydration number of natural gas hydrate decides its quality and depends on the temperature and the pressure (water depth). We applied Raman spectroscopy for the natural gas hydrates retrieved off Sakhalin Island and off Abashiri (Japan Sea and the Sea of Okhotsk) to estimate the hydration number of natural gas hydrates. We confirmed no relation between the hydration number of natural gas hydrates and the water depth. We also checked the effect of hydrogen sulfide on the hydration number using synthetic mixed gas (methane and hydrogen sulfide) hydrates, and found that the molecules of hydrogen sulfide prefer to be encaged in small cages, whereas the molecular diameter of hydrogen sulfide is larger than that of methane. Therefore, we may overestimate the hydration number of natural gas hydrate supposing that they are pure methane hydrate.