Study on CO₂ hydrate formation characteristics with promoters for CO₂ capture and cold thermal energy transportation

Advancing in a cleaner production and environement, hydrate-based CO₂ capture techniques have been spotlighted as a potential future carbon capture technology. The technique allows CO₂ to be captured in the form of a hydrate which is capable of storing or transporting CO₂ with higher efficiency. Furthermore, CO₂ hydrates can be used as energy carriers by capturing the cold thermal energy. Thus, CO₂ hydrates can enable effective transportation for both CO₂ and cold thermal energy. In this study, the characteristics of CO₂ hydrates in the presence of prevalent promoters are studied extensively from various perspectives. CO₂ hydrates were produced in an agitating closed absorption chamber under various pressure and promoter concentration conditions with three prevalent promoters: cyclopentane, tetrahydrofuran and tetra-n-butylammonium bromide. Comparison of the promoters under various conditions was carried out by investigating the characteristics during and after hydrate formation. Additionally, the thermal behavior during hydrate formation was observed through the temperature variation to investigate the inside of the chamber during the formation process. Moreover, to understand the CO₂ hydrate structures in the presence of the promoters, microscopic and spectroscopic approaches were applied using focused ion beam scanning electron microscopy and X-ray diffraction methods. The CO₂ capture performance and characteristics of the CO₂ hydrate absorbents were evaluated.