Hydrogen Separation from Greenhouse Gas-Containing Mixtures via Clathrate Hydrate Formation

초록

Gas hydrates, crystalline inclusion compounds formed under specific thermodynamic conditions, have garnered growing interest as a sustainable and energy-efficient medium for gas separation processes. This review presents a comprehensive examination of hydrate-based separation technologies, with a focus on hydrogen (H2) separation from methane (CH4) and carbon dioxide (CO2) mixtures. The fundamental structures and properties of clathrate hydrates are first introduced, followed by a discussion of pure hydrates and their limitations for practical gas separation. The review then addresses the role of binary hydrates, where guest molecule combinations enhance hydrate formation and selectivity, and semi-clathrate hydrates, where ionic promoters like tetra-n-butylammonium bromide (TBAB) lower the formation pressure and influence gas selectivity. Special attention is paid to the thermodynamic and kinetic behaviors of H2 + CH4 and H2 + CO2 systems in various hydrate environments. The synergistic effects of additional components such as cyclopentane (CP) and surfactants like sodium dodecyl sulfate (SDS) are analyzed for their ability to enhance gas uptake and separation efficiency. Finally, the review covers advances in hydrate formation within porous supports such as silica gels, which offer a promising pathway to overcome kinetic barriers and facilitate static, low-energy operation. Overall, this article consolidates key findings and experimental insights to provide a current understanding of the hydrate-based hydrogen separation field, offering a valuable resource for further development and application.

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