High storage capacity and rapid methane hydrate formation using low concentrations of a new surfactant: A mimic of SDS and amino acid scaffold

Abstract

The development of efficient, non-foaming promoters is essential for advancing the industrial applications of solidified gas hydrates in carbon capture, natural gas storage, and transportation. In this study, a novel surfactant, containing sulfonate, amide, and carboxyl groups (SSAC), was introduced as a promoter for methane hydrate formation. SSAC was synthesized by integrating the chemistries of amino acids and sodium dodecyl sulfate (SDS), distinguishing it from existing promoters. High-pressure autoclave experiments demonstrated that SSAC significantly enhanced the kinetics of methane hydrate formation, at a low concentration of 5 ppm, achieving a maximum water-to-hydrate conversion of 85.2 %, equivalent to a storage capacity of 163.5 v/v in deionized water. Increasing the SSAC concentration to 500 ppm resulted in an impressive conversion rate of 94.6 % and a storage capacity of 181.6 v/v. Methane recovery was accomplished without foaming within 15 min during hydrate dissociation at room temperature, addressing a critical challenge in current hydrate-based storage systems. Molecular dynamics simulations further revealed that SSAC molecules act as collectors for methane molecules in solution, thereby enhancing the rate of hydrate growth and increasing the number of hydrate cavities. Notably, SSAC exhibited a biodegradation level of 41 % after 28 days, indicating its potential for natural degradation and environmental compatibility. This combination of low concentration efficiency, foam-free formation, environmental sustainability, and enhanced methane collection is unprecedented in the current literature, highlighting the innovative nature of this work. These findings suggest that the integration of amino acid structures with anionic surfactants offers a promising strategy for designing effective promoters, with significant implications for energy storage, seawater desalination, and carbon capture technologies.