Hydrate Kinetics Study in the Presence of Nonaqueous Liquid by Nuclear Magnetic Resonance Spectroscopy and Imaging

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DOIResolve DOI: http://doi.org/10.1021/jp061980yS1520-6106(06)01980-8
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TypeArticle
Journal titleThe Journal of Physical Chemistry B: Condensed Phase
ISSN15206106
Volume110
Issue51
Pages2580325809; # of pages: 7
AbstractThe dynamics of methane hydrate growth and decomposition were studied by nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI). Three well-known large molecule guest substances (LMGS) were used as structure H hydrate formers: 2,2-dimethylbutane (NH), methylcyclohexane (MCH), tert-butyl methyl ether (TBME). In addition, the impact of a non-hydrate former (n-heptane/nC7) was studied. The methane diffusion and hydrate growth were monitored by recording the 2H NMR spectra at 253 K and ~4.5 MPa for 20 h. The results revealed that methane diffuses faster in TBME and NH, slower in nC7, and slowest in MCH. The TBME system gives the fastest hydrate formation kinetics followed by NH, MCH, and nC7. The conversion of water into hydrate was also observed. The imaging study showed that TBME has a strong affinity toward ice, which is not the case for the NH and MCH systems. The degree of ice packing was also found to affect the LMGS distribution between ice particles. Highly packed ice increases the mass transfer resistance and hence limits the contact between LMGS and ice. It was also found that "temperature ramping" above the ice point improves the conversion significantly. Finally, hydrates were found to dissociate quickly within the first hour at atmospheric pressure and subsequently at a much slower rate. Methane dissolved in LMGS was also seen. The residual methane in hydrate phase and dissolved in LMGS phase explain the faster kinetics during hydrate re-formation.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences
Peer reviewedYes
Identifier18077705
NPARC number12338903
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Record identifier331351e1-227b-46c3-b6c0-ca5a23f59685
Record created2009-09-11
Record modified2017-03-23
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