Cyclodextrins as eco-friendly nucleation promoters for methane hydrate

Fariba Asadi, Peter J. Metaxas, Vincent W.S. Lim, Tuan A.H. Nguyen, Zachary M. Aman, Eric F. May, Anh V. Nguyen

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Gas hydrates offer potential methods for the storage and transportation of gases. However, factors such as slow kinetics can hinder storage applications. Here we demonstrate the use of cyclodextrins (CDs) as green chemicals for accelerating methane hydration formation. A second generation high pressure, stirred, automated lag time apparatus (HPS-ALTA) was used to determine the hydrate formation probability as a function of CD concentration, subcooling, and time. Nucleation rates were increased for all three studied (α, β, and γ) CDs, as determined from formation measurements under ramped and fixed temperatures. Analysis of the ramped temperature experiments suggests that the nucleation promotion is related to a CD-induced reduction in the thermodynamic nucleation parameter which provides a measure of nucleation work. Hydrate formation in the presence of CDs was also confirmed to be consistent with the mononuclear nucleation process predicted by the classical nucleation theory. Rates of initial growth were also measured but showed no CD dependence. At the optimum CD loadings found for nucleation, the highest and lowest levels of nucleation promotion were observed for α- and β-CD, respectively. These CDs also generated the highest and lowest levels of H-bonding disruption at the gas-water interface (as measured by sum frequency generation spectroscopy), respectively, suggesting that such disruption may play a role in the hydrate nucleation promotion in CD-containing systems.

Original languageEnglish
Article number127932
JournalChemical Engineering Journal
DOIs
Publication statusE-pub ahead of print - 2 Dec 2020

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