2-12　CO₂ハイドレートのゲストガス安定同位体分別とその要因について

抄録

Natural CO₂ hydrates are found in nature. Stable isotope ratio of guest gas provides useful information to know gas origin and formation processes. Recently, the difference in the equilibrium pressures of the hydrates containing CH₄ and CH₃D, respectively, has been detected and shown to be consistent with the results of hydrogen isotope fractionation of methane during formation of methane hydrate. In this study, carbon isotope fractionation during formation of CO₂ hydrate and the difference in the equilibrium pressure of hydrate between CO₂ isotopologues were investigated. The results show that ¹³CO₂ molecules are less likely to be encaged in the hydrate lattice than ¹²CO₂ molecules, because the equilibrium pressure of the ¹³CO₂ hydrate is slightly higher than that of ¹²CO₂.