Large amounts of CH4 in the form of solid hydrates are stored on continental margins and in
permafrost regions. If these CH4 hydrates could be converted into CO2 hydrates, they would serve
double duty as CH4 sources and CO2 storage sites. Herein, we report the swapping phenomena
between global warming gas and various structures of natural gas hydrate including sI, sII, and sH
through 13C solid-state nuclear magnetic resonance, and FT-Raman spectrometer. The present
outcome of 85% CH4 recovery rate in sI CH4 hydrate achieved by the direct use of binary N2 +
CO2 guests is quite surprising when compared with the rate of 64 % for a pure CO2 guest attained
in the previous approach. The direct use of a mixture of N2 + CO2 eliminates the requirement of a
CO2 separation/purification process. In addition, the simultaneously-occurring dual mechanism of
CO2 sequestration and CH4 recovery is expected to provide the physicochemical background
required for developing a promising large-scale approach with economic feasibility. In the case of
sII and sH CH4 hydrates, we observe a spontaneous structure transition to sI during the
replacement and a cage-specific distribution of guest molecules. A significant change of the
lattice dimension due to structure transformation induces a relative number of small cage sites to
reduce, resulting in the considerable increase of CH4 recovery rate. The mutually interactive
pattern of targeted guest-cage conjugates possesses important implications on the diverse hydratebased
inclusion phenomena as clearly illustrated in the swapping process between CO2 stream
and complex CH4 hydrate structure.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/1153 |
| Date | 07 1900 |
| Creators | Park, Youngjune, Cha, Minjun, Cha, Jong-Ho, Shin, Kyuchul, Lee, Huen, Park, Keun-Pil, Juh, Dae-Gee, Lee, Ho-Young, Kim, Se-Joon, Lee, Jaehyoung |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Rights | Park, Youngjune; Cha, Minjun; Cha, Jong-Ho; Shin, Kyuchul; Lee, Huen; Park, Keun-Pil; Juh, Dae-Gee; Lee Ho-Young; Kim, Se-Joon; Lee, Jaehyoung. |
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