| 초록 |
Natural gas hydrates have been considered as future energy resources due to their huge amount of deposits. Among various production methods, the CH4-CO2 replacement has been studied as a promising technology which has a dual function of CH4 production and CO2 sequestration. In this study, CO2+N2 gas were injected into the CH4 + methylcyclopentane (MCP) hydrate of structure H (sH) to examine the influence of feed gas compositions on structural transformation and guest exchange behavior in the sH hydrates. Three different gas mixtures (CO2 20%, 40%, and 60%) were used. The replacement efficiency was measured using GC and the structural transition was confirmed through 13C NMR and PXRD with Rietveld analysis. The experimental results showed that higher CO2 compositions in the feed gas contributed to the increased structural transition to structure I and also resulted in lower guest exchange due to lower N2 inclusion. Because of the trade-off between structural transition and N2 inclusion, the highest replacement efficiency was found at the feed gas composition of CO2(40%)+N2(60%). |
