Gas Hydrate-Based F-Gas (CHF3 and C2F6) Separation: Thermodynamic and Spectroscopic Approaches

Abstract

CHF3 (fluoroform, HFC-23) and C2F6 (hexafluoroethane, R-116) are the most common F-gases which are primarily utilized in the semiconductor industry and refrigeration system due to their high stability compared to other industrial gases. However, since they have significant global warming potential and long atmospheric lifetime, their emission to the atmosphere should be reduced in order to mitigate the accelerating global warming effect. Therefore, gas hydrate-based F-gas capture was recently suggested as the solution for the prevention of F-gas emission. To examine the feasibility of the gas hydrate-based F-gas separation, the N2 + CHF3 (10, 20, 40, 60, 80%) and N2 + C2F6 (10, 20, 40, 60, 80%) gas hydrates were investigated with a primary focus on phase equilibria and preferential partitioning of guest molecules. Also, the composition changes of the vapor and hydrate phases and the gas uptake during the hydrate formation were investigated at two different temperature conditions. Furthermore, in-situ Raman spectroscopy revealed the cage filling behaviors of CHF3 molecules in CHF3 + N2 mixed gas hydrates.