Energy & Fuels 2006, 20, 1197-1200
1197
Temperature-Gradient Assisted Gas-Dissolved Liquid-Phase Synthesis of Clathrate Hydrates Raffie Avakian, Yougang Mao, Danny Chagolla, and Yong Ba* Department of Chemistry and Biochemistry, California State UniVersity Los Angeles, 5151 State UniVersity DriVe, Los Angeles, California 90032 ReceiVed September 28, 2005. ReVised Manuscript ReceiVed February 26, 2006
A novel laboratory method to synthesize clathrate hydrates in sealed glass tubes is described in this manuscript. It was known that the major obstacle in the synthesis of a gas hydrate is from the slow mass transport through the hydrate layer. To circumvent this problem in a sealed glass tube, we developed a temperature-gradient assisted gas-dissolved liquid-phase reaction. This method allows a clathrate hydrate start to form at the bottom of a glass tube and then grow through the diffusion of gas molecules from the gas phase passing through the liquid water phase to the water-gas hydrate interface. This method takes advantage of the fact that gases diffuse much faster in a liquid phase than in a gas-hydrate solid phase. Three examples to synthesize D2O/Xe, D2O/THF/Xe, and D2O/propane gas hydrates are given. The formations of the first two gas hydrates were verified with 129Xe and 129Xe T1 NMR experiments, and that of the last one was verified with 13C and 2H-1H QEDOR NMR experiments.
I. Introduction Clathrate hydrates (also called gas hydrates) are a class of crystals consisting of small nonpolar molecules (
