Multiscale Analysis on CH4-CO2 Swapping Phenomenon Occurred in Hydrates

Swapping CH4 with CO2 in hydrocarbon hydrates is renowned as an eco-friendly method for potential energy production and climate change mitigation. To fully understand the CH4-CO2 replacement process, in situ Raman spectroscopy combined with long-term macroscopic measurements were carried out by putt...

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Bibliographic Details
Published in:The Journal of Physical Chemistry C
Main Authors: Zhou, Xuebing, Lin, Fuhua, Liang, Deqing
Format: Article in Journal/Newspaper
Language:English
Published: 2016
Subjects:
Science & Technology
Physical Sciences
Technology
Chemistry
Science & Technology - Other Topics
Materials Science
NATURAL-GAS HYDRATE
METHANE HYDRATE
CARBON-DIOXIDE
LIQUID CO2
IN-SITU
RAMAN-SPECTROSCOPY
CURRENT KNOWLEDGE
PRESSURIZED CO2
CH4 HYDRATE
REPLACEMENT
Physical
Nanoscience & Nanotechnology
Multidisciplinary
Methane hydrate
Online Access:http://ir.giec.ac.cn/handle/344007/13978
https://doi.org/10.1021/acs.jpcc.6b07444
Description
Summary:Swapping CH4 with CO2 in hydrocarbon hydrates is renowned as an eco-friendly method for potential energy production and climate change mitigation. To fully understand the CH4-CO2 replacement process, in situ Raman spectroscopy combined with long-term macroscopic measurements were carried out by putting CH4 hydrates into gaseous CO2 at temperatures ranging from 273.2 to 281.2 K. A kinetic model based on gas diffusion theory was modified. Results showed that the gas swapping process started with surface reaction followed by gas diffusion in hydrate phase. At hydrate surface, the average occupancy of CH4 decreased without dramatic fluctuations, suggesting that the replacements were not simply composed of a series of dissociation and reformation process. A rise in temperature was found to effectively increase the gas swapping rates and strengthen the gas diffusion in hydrate phase. In situ Raman results together with gas consumption data were fitted by the kinetic model. The calculated gas-hydrate interfacial area revealed the foamy nature of hydrates. Fitting parameters representing the gas diffusion coefficient were of the same order of magnitude as the water mobility in hydrate phase, which implied that the replacements were limited by the mobility of water molecules.

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