Gas Flow Rate and Temperature Dependence of the Kinetics of Difluoromethane Clathrate Hydrate Formation from CF2H2 Gas and Ice Particles

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• 作者：Michael T. Nguyen ; Jaruwan Amtawong ; Karena Smoll ; Andrew Chanez ; Michael Yamano ; Gia-Bao H. Dinh ; Suvrajit Sengupta ; Rachel W. Martin ; Kenneth C. Janda
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：April 28, 2016
• 年：2016
• 卷：120
• 期：16
• 页码：8482-8489
• 全文大小：343K
• 年卷期：0
• ISSN：1932-7455

文摘

The effects of temperature and gas flow rate on the formation kinetics of difluoromethane clathrate hydrate from CF₂H₂ gas and <38 μm diameter ice particles were investigated. The early stage of the reaction exhibits a negative correlation with temperature that is characterized by an activation energy of −7.2 ± 0.7 kJ/mol(H₂O) for the 6 mmol/h flow rate and −6.7 ± 1.5 kJ/mol(H₂O) for 19 mmol/h. We surmise that the origin of the negative activation energy involves the existence of an unstable structure or gas adsorption to the ice surface. Although the effect of flow rate on the observed activation energy is modest, other aspects of the kinetics are more dramatically affected. Initially, the reaction is faster for the higher flow rate simply because more gas is available for the reaction. However, the reaction stalls for a lower percent yield for the faster flow rate. We postulate that the fast flow rate creates more uniform hydrate formation over the ice surface, resulting in the onset of stage III kinetics at a lower percent yield. Both the temperature and flow rate dependence of the formation kinetics have important implications for practical applications of clathrate hydrates for gas storage and transportation.