Energies 2012, 5(2), 420-437; doi:10.3390/en5020420
Article

The Driving Forces of Guest Substitution in Gas Hydrates—A Laser Raman Study on CH4-CO2 Exchange in the Presence of Impurities

Helmholtz Centre Potsdam, German Research Centre for Geosciences (GFZ), Telegrafenberg, 14473 Potsdam, Germany
* Author to whom correspondence should be addressed.
Received: 15 December 2011; in revised form: 2 February 2012 / Accepted: 14 February 2012 / Published: 22 February 2012
(This article belongs to the Special Issue Natural Gas Hydrate 2011)
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Abstract: The recovery of CH4 gas from natural hydrate formations by injection of industrially emitted CO2 is considered to be a promising solution to simultaneously access an unconventional fossil fuel reserve and counteract atmospheric CO2 increase. CO2 obtained from industrial processes may contain traces of impurities such as SO2 or NOx and natural gas hydrates may contain higher hydrocarbons such as C2H6 and C3H8. These additions have an influence on the properties of the resulting hydrate phase and the conversion process of CH4-rich hydrates to CO2-rich hydrates. Here we show results of a microscopic and laser Raman in situ study investigating the effects of SO2-polluted CO2 and mixed CH4-C2H6 hydrate on the exchange process. Our study shows that the key driving force of the exchange processes is the establishment of the chemical equilibrium between hydrate phase and the surrounding phases. The exchange rate is also influenced by the guest-to-cavity ratio as well as the thermodynamic stability in terms of p-T conditions of the original and resulting hydrate phase. The most effective molecule exchange is related to structural changes (sI-sII) which indicates that hydrate decomposition and reformation processes are the occurring processes.
Keywords: gas hydrate; CH4-CO2 exchange; SO2; C2H6; chemical equilibrium; sI-sII conversion

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MDPI and ACS Style

Beeskow-Strauch, B.; Schicks, J.M. The Driving Forces of Guest Substitution in Gas Hydrates—A Laser Raman Study on CH4-CO2 Exchange in the Presence of Impurities. Energies 2012, 5, 420-437.

AMA Style

Beeskow-Strauch B, Schicks JM. The Driving Forces of Guest Substitution in Gas Hydrates—A Laser Raman Study on CH4-CO2 Exchange in the Presence of Impurities. Energies. 2012; 5(2):420-437.

Chicago/Turabian Style

Beeskow-Strauch, Bettina; Schicks, Judith Maria. 2012. "The Driving Forces of Guest Substitution in Gas Hydrates—A Laser Raman Study on CH4-CO2 Exchange in the Presence of Impurities." Energies 5, no. 2: 420-437.

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