The Driving Forces of Guest Substitution in Gas Hydrates—A Laser Raman Study on CH 4 -CO 2 Exchange in the Presence of Impurities

Autor: Bettina Beeskow-Strauch, Judith Maria Schicks
Rok vydání: 2012
Předmět:
Zdroj: Energies. 5:1-18
Popis: The recovery of CH 4 gas from natural hydrate formations by injection of industrially emitted CO 2 is considered to be a promising solution to simultaneously access an unconventional fossil fuel reserve and counteract atmospheric CO 2 increase. CO 2 obtained from industrial processes may contain traces of impurities such as SO 2 or NO x and natural gas hydrates may contain higher hydrocarbons such as C 2 H 6 and C 3 H 8 . These additions have an influence on the properties of the resulting hydrate phase and the conversion process of CH 4 -rich hydrates to CO 2 -rich hydrates. Here we show results of a microscopic and laser Raman in situ study investigating the effects of SO 2 -polluted CO 2 and mixed CH 4 -C 2 H 6 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.
Databáze: OpenAIRE
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