Abstract
Natural gas hydrates are solid hydrogen-bonded water crystals containing small molecular gases. The amount of natural gas stored as hydrates in permafrost and ocean sediments is twice that of all other fossil fuels combined. However, hydrate blockages also hinder oil/gas pipeline transportation, and, despite their huge potential as energy sources, our insufficient understanding of hydrates has limited their extraction. Here, we report how the presence of amino acids in water induces changes in its structure and thus interrupts the formation of methane and natural gas hydrates. The perturbation of the structure of water by amino acids and the resulting selective inhibition of hydrate cage formation were observed directly. A strong correlation was found between the inhibition efficiencies of amino acids and their physicochemical properties, which demonstrates the importance of their direct interactions with water and the resulting dissolution environment. The inhibition of methane and natural gas hydrate formation by amino acids has the potential to be highly beneficial in practical applications such as hydrate exploitation, oil/gas transportation, and flow assurance. Further, the interactions between amino acids and water are essential to the equilibria and dynamics of many physical, chemical, biological, and environmental processes.
Highlights
Korea Institute of Industrial Technology, 30 Gwahaksandan 1-Ro 60Beon-Gil, Gangseo-Gu, Busan 618-230, Korea. †Present address: Chemical & Biological Engineering Department, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, Unites States
The addition of amino acids to CH4 hydrates does not alter the crystal structure, as is the case for the CO2 hydrate system[18,25], diffraction peaks for hexagonal ice are evident (Fig. 1c), which indicates that the conversion of water to hydrates has been interrupted and that the liquid water freezes during the liquid N2 quenching[18,25]
Similar results were obtained for the natural gas (NG) hydrates (Fig. 1e); the only difference is the presence of a weak diffraction peak for the structure I hydrate, which is consistent with previous reports[22,23,24]
Summary
A systematic comparison of the inhibition efficiencies of amino acids is required. Previous investigations into hydrate inhibition by amino acids have been limited to CO217–19, ethane[20], and tetrahydrofuran[21] hydrates, CH4 and NG hydrates are more important for flow assurance. We examined the inhibition by amino acids of CH4 and NG hydrate formation. Amino acids have significant potential for industrial applications that require the inhibition of CH4 and NG hydrate formation such as the exploitation of hydrates, oil/gas pipeline transportation, and flow assurance. The environmental friendliness of amino acids means that they can be used in areas with severe contamination risks
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
