Methane conversion rate into structure H hydrate crystals from ice

Abstract

in Wiley InterScience (www.interscience.wiley.com).The methane uptake and conversion rate to structure H (sH) hydrates was measured and compared to crystallization kinetics models. Three large molecule guest substances (LMGS) were used as sH hydrate formers: neohexane (NH), methylcyclohexane (MCH), and tert-butyl methyl ether (TBME). The initial crystallization occurred quickly at the LMGS liquid-ice interface until $20-30% of ice was converted into hydrate (hydrate growth stage I). Slower hydrate crystal growth was observed after a hydrate film covered the ice surface at a rate of 3-400 nm 2 /h (hydrate growth stage II). The TBME system showed the fastest kinetics at the beginning of the reaction followed by NH and MCH system. However the trend changed when the temperature was increased (''reaction'' stage III). Surprisingly, the conversion rate achieved with the TBME system upon melting the ice was the smallest. This was attributed to the strong interaction of TBME with water molecules that increased the energy barrier for water molecules to form hydrate cages. The conversion rates were well correlated with the Avrami equation and the shrinking core model. Finally, NH was found to be the best LMGS in this study to obtain full conversion within a short reaction time and achieving high methane gas storage in the hydrate.

Systematic kinetic studies on mixed gas hydrates by Raman spectroscopy and powder X-ray diffraction

“…Random nucleation followed by the growth of the nuclei is often modelled using the Avrami rate law (also known as Avrami-Erofeev or JohnsonMehl-Avrami-Kolmogorow equation) [23,24]. This equation has been successfully used before to fit data from hydrate formation experiments [2,11,14]. The reaction extent α can be given by a general expression of the Avrami rate law being…”

“…A similar approach for modelling the formation of structure H hydrates from ice was favoured by Susilo et al [14]. The authors state that the initial reaction is controlled by intrinsic kinetics and can be therefore fitted with the Avrami equation.…”

Static Formation and Dissociation of Methane+Methylcyclohexane Hydrate for Gas Hydrate Production and Regasification

“…The kinetic behaviors of sH methane hydrate formation and decomposition with stirring or spraying have been studied by several researchers [9][10][11][12][13][14]. According to their studies, the rate of methane fixation by sH hydrate formation at lower pressures may even exceed that by sI hydrate formation at higher pressures [11,15].…”

Capture of carbon dioxide from flue or fuel gas mixtures by clathrate crystallization in a silica gel column

“…Tsouris and co-workers have presented novel and efficient crystallizers in the context of CO 2 sequestration work (Lee et al, 2003;Tsouris et al, 2004Tsouris et al, , 2007West et al, 2001). In addition, it has also been reported that when hydrate is formed from ice, temperature ramping enhances the conversion (Susilo et al, 2007b;Wang et al, 2002).…”