Phase equilibria and azeotropic behavior of C2F6+ N2 gas hydrates
| Autor: | Yongwon Seo, Eunae Kim, Gyeol Ko |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Chemistry
Clathrate hydrate Thermodynamics 02 engineering and technology 010501 environmental sciences 01 natural sciences Atomic and Molecular Physics and Optics chemistry.chemical_compound 020401 chemical engineering Phase (matter) Azeotrope Hexafluoroethane General Materials Science Gas separation 0204 chemical engineering Physical and Theoretical Chemistry Ternary operation Hydrate Powder diffraction 0105 earth and related environmental sciences |
| Zdroj: | The Journal of Chemical Thermodynamics. 117:43-47 |
| ISSN: | 0021-9614 |
| Popis: | C2F6 (hexafluoroethane, R116) is a fluorinated gas (F-gas) widely used in semiconductor industries, which also has a high global warming potential and a long atmospheric lifetime. In this study, the thermodynamic and structural characteristics of the C2F6 + N2 gas hydrates were investigated for gas hydrate-based C2F6 separation from emission sources. This experiment measured the three-phase (hydrate, liquid water, and vapor [H-LW-V]) equilibria of ternary C2F6 (10, 20, 40, 60, and 80%) + N2 + H2O systems and indicated the possible existence of hydrate azeotropes at certain temperature ranges. Powder X-ray diffraction (PXRD) revealed that the ternary C2F6 + N2 + H2O systems form structure II (sII) hydrates (Fd3m) for all C2F6 concentrations considered in this study. The pressure-composition diagram obtained at two different temperatures (275.15 K and 279.15 K) demonstrated that C2F6 is highly enriched in the hydrate phase at 275.15 K, whereas at 279.15 K, the C2F6 + N2 + H2O systems have a hydrate azeotrope where the composition of the hydrate phase is the same as the composition of the vapor phase. The overall experimental results clearly indicate that hydrate-based C2F6 separation is thermodynamically feasible and the higher separation efficiency is achievable at lower temperature ranges. |
| Databáze: | OpenAIRE |
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