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Macro and microscopic CH 4 –CO 2 replacement in CH 4 hydrate under pressurized CO 2
Author(s) -
Ota Masaki,
Saito Takeomi,
Aida Tsutomu,
Watanabe Masaru,
Sato Yoshiyuki,
Smith Richard L.,
Inomata Hiroshi
Publication year - 2007
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.11294
Subject(s) - fugacity , hydrate , van der waals force , chemistry , clathrate hydrate , raman spectroscopy , analytical chemistry (journal) , cage , decomposition , thermodynamics , phase (matter) , materials science , chromatography , organic chemistry , physics , mathematics , combinatorics , molecule , optics
CH 4 –CO 2 replacement in CH 4 hydrate with high pressure CO 2 was studied with in‐situ laser Raman spectroscopy at 273.2 K and at initial pressures of 3.2, 5.4, and 6.0 MPa. Replacement rates increased with increasing pressures up to 3.6 MPa and did not change at higher pressures (∼6.0 MPa). These results showed that the replacement rates were dependent on pressure and phase conditions with the driving force being strongly related to fugacity differences of the two guest components between fluid and hydrate phases. When CH 4 hydrate was contacted with CO 2 under flow conditions, in‐situ Raman measurements of the hydrate phase showed differences of cage decomposition rates between the Medium‐cage (M‐cage) and the Small‐cage (S‐cage) in the CH 4 hydrate with decomposition of the M‐cage being faster than that of the S‐cage. The van der Waals–Platteeuw model was applied to the measurements of the transient data and it is shown that the theory allows estimation of occupancies of each component during replacement. © 2007 American Institute of Chemical Engineers AIChE J, 2007