Separation of SF6 from Gas Mixtures Using Gas Hydrate Formation

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• 作者：Inuk Cha ; Seungmin Lee ; Ju Dong Lee ; Gang-woo Lee ; Yongwon Seo
• 刊名：Environmental Science & Technology
• 出版年：2010
• 出版时间：August 15, 2010
• 年：2010
• 卷：44
• 期：16
• 页码：6117-6122
• 全文大小：231K
• 年卷期：v.44,no.16(August 15, 2010)
• ISSN：1520-5851

文摘

This study aims to examine the thermodynamic feasibility of separating sulfur hexafluoride (SF₆), which is widely used in various industrial fields and is one of the most potent greenhouse gases, from gas mixtures using gas hydrate formation. The key process variables of hydrate phase equilibria, pressure−composition diagram, formation kinetics, and structure identification of the mixed gas hydrates, were closely investigated to verify the overall concept of this hydrate-based SF₆ separation process. The three-phase equilibria of hydrate (H), liquid water (L_W), and vapor (V) for the binary SF₆ + water mixture and for the ternary N₂ + SF₆ + water mixtures with various SF₆ vapor compositions (10, 30, 50, and 70%) were experimentally measured to determine the stability regions and formation conditions of pure and mixed hydrates. The pressure−composition diagram at two different temperatures of 276.15 and 281.15 K was obtained to investigate the actual SF₆ separation efficiency. The vapor phase composition change was monitored during gas hydrate formation to confirm the formation pattern and time needed to reach a state of equilibrium. Furthermore, the structure of the mixed N₂ + SF₆ hydrate was confirmed to be structure II via Raman spectroscopy. Through close examination of the overall experimental results, it was clearly verified that highly concentrated SF₆ can be separated from gas mixtures at mild temperatures and low pressure conditions.