| 초록 |
Natural gas hydrates are regarded as a future clean energy source. The CH4-flue gas replacement in naturally occurring gas hydrates has been recently suggested for the CO2 sequestration and CH4 recovery. In spite of the predominance of structure I (sI) and structure II (sII) hydrate reservoirs in nature, it was reported that struecture H (sH) hydrates also naturally occur. For the CH4-flue gas replacement based on sH hydrates, it is important whether CO2 functions as a co-guest in sH hydrates and enclathrated CO2 affects structural transition in terms of CO2 sequestration. In this study, the effect of sH hydrate formation on the three-phase (H-Lw-V) equilibria of the mixed gas hydrate was investigated. The structures of these hydrates were analyzed to ensure the enclathration of CO2 in sH hydrates and to verify structural transition sH into sI hydrate via Raman spectroscopy, X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The CO2 hydrate compositions were measured via gas chromatography to determine the CO2 storage capacity. From these experiments, it was verified that CO2 functions as a co-guest of sH hydrate in the N2-enriched system, and structural transition of sH to sI occurs in the CO2-enriched system. |
