Selective CO Capture from CO/N Gas Mixtures Utilizing Tetrabutylammonium Fluoride Hydrates.

Gas hydrates, a type of inclusion compound capable of trapping gas molecules within a lattice structure composed of water molecules, are gaining attention as an environmentally benign gas storage or separation platform. In general, the formation of gas hydrates from water requires high-pressure and low-temperature conditions, resulting in significant energy consumption. In this study, tetrabutylammonium fluoride (TBAF) was utilized as a thermodynamic promoter forming a semi-clathrate-type hydrate, enabling gas capture or separation at room temperature. Those TBAF hydrate systems were explored to check their capability of CO separation from flue gas, the mixture of CO and N gases. The formation rates and gas storage capacities of TBAF hydrates were systematically investigated under various concentrations of CO, and they presented selective CO capture behavior during the hydrate formation process. The maximum gas storage capacities were achieved at 2.36 and 2.38 mmol/mol for TBAF·29.7 HO and TBAF·32.8 HO hydrate, respectively, after the complete enclathration of the feed gas of CO (80%) + N (20%). This study provides sufficient data to support the feasibility of TBAF hydrate systems to be applied to CO separation from CO/N gas mixtures based on their CO selectivity.