Time-Dependent Studies of Hydrates

Up until around the mid-1990s, there were only a limited number of groups investigating the time-dependent properties of hydrates. These groups include  

Since around the mid-1990s, there has been a proliferation of hydrate time-dependent studies. These include macroscopic, mesoscopic, and molecular-level measurements and modeling efforts. A proliferation of kinetic measurements marks the maturing of hydrates as a field of research. Typically, research efforts begin with the consideration of time-independent thermodynamic equilibrium properties due to relative ease of measurement. As an area matures and phase equilibrium thermodynamics becomes better defined, research generally turns to time-dependent measurements such as kinetics and transport properties. 

Measurement and modeling of time-dependent hydrate properties is clearly far more challenging than time-independent (thermodynamic) hydrate properties. Although significant advances have been achieved in measurement and modeling 

Microscopic time-resolved measurements of the hydrate phase during gas hydrate formation, decomposition, and inhibition began only in the mid-1990s. These techniques include in situ synchrotron x-ray diffraction (Koh et al., 1996 Klapproth et al., 2003 Uchida et al., 2003), neutron diffraction (Henning et al., 2000 Koh et al., 2000 Halpern et al., 2001 Staykova et al., 2003), Raman spectroscopy (Subramanian and Sloan, 2002 Komai et al., 2004), and NMR spectroscopy (Moudrakovski et al., 2001 Kini et al., 2004 Gupta et al., 2007). 

Computer simulations provide a means of examining the early stages of hydrate formation (nucleation) on a molecular level (Baez and Clancy, 1994 Radhakrishnan and Trout, 2002 Moon et al., 2003, 2005). Computer simulation has also been applied to study hydrate dissociation (Baez and Clancy, 1994 English and MacElroy, 2004) and the effects on dissociation kinetics of external electromagnetic fields (English and MacElroy, 2004). 

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