Replacement of Methane Hydrate by Carbon Dioxide: ~(13)C NMR Study for Studying a Limit to the Degree of Substitution

摘要

The results presented here show that, at least in a laboratory setting, the replacement of CH_4 by CO_2 is favored from the points of view of equilibrium thermodynamics. Pure and mixed-phase hydrates were prepared in porous silica gel in order to observe the guest distribution in hydrate cages by ~(13)C NMR spectroscopy. The resulting ratio values for CH_4 in small and large cages strongly suggested that at least 64% of methane should be recoverable from a hydrate of composition CH_4·6.05H_2O.