Phase equilibrium for clathrate hydrates formed from an ozone+oxygen gas mixture coexisting with carbon tetrachloride or 1,1-dichloro-1-fluoroethane

Sanehiro Muromachi, Takahiro Nakajima, Ryo Ohmura, Yasuhiko H. Mori

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

This paper reports an attempt at acquiring phase-equilibrium pressure (p) versus temperature (T) data for ozone-containing clathrate hydrates formed from an ozone+oxygen gas mixture, a hydrophobic hydrate-forming liquid, and water in the liquid state. For dealing with ozone (O3), a chemically unstable material continuously decaying to oxygen (O2) in the gas phase, we devised a new method, i.e., a modified pressure-search method, to determine the equilibrium p-T conditions while maintaining the ozone concentration in the gas phase nearly constant by repeatedly replacing the contents of the gas phase with a freshly generated O3+O2 mixture. Using carbon tetrachloride (CCl4) as the hydrophobic hydrate-forming liquid, we obtained equilibrium p-T data in the range of 0.167MPa≤p≤0.361MPa and 275.6K≤T≤277.3K in the presence of a gas phase containing O3 at the molar concentration of 6.9±0.8%. We also obtained, for comparison, the corresponding p-T data, using pure O2 gas, instead of the O3+O2 mixture, and the conventional pressure-search method. The two data groups obtained from the O3-containing and O3-free systems, respectively, show simple, mutually consistent p-T relations each well fitted by the Clausius-Clapeyron equation assuming a constant enthalpy of hydrate dissociation. The paper also describes our additional attempt at obtaining equilibrium p-T data using 1,1-dichloro-1-fluoroethane (R141b) as a substitute for CCl4. Because of the partial decomposition of R141b due to the coexistence of O3 and water, however, we obtained only limited data which are tentative in nature.

Original languageEnglish
Pages (from-to)145-151
Number of pages7
JournalFluid Phase Equilibria
Volume305
Issue number2
DOIs
Publication statusPublished - 2011 Jun 25

Fingerprint

Carbon tetrachloride
Carbon Tetrachloride
Ozone
clathrates
carbon tetrachloride
Hydrates
Gas mixtures
Phase equilibria
hydrates
ozone
gas mixtures
Gases
vapor phases
Oxygen
oxygen
liquids
Liquids
Water
water
enthalpy

Keywords

  • Clathrate hydrates
  • Gas hydrates
  • Mixed hydrates
  • Ozone
  • Phase equilibria

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Physical and Theoretical Chemistry
  • Physics and Astronomy(all)

Cite this

Phase equilibrium for clathrate hydrates formed from an ozone+oxygen gas mixture coexisting with carbon tetrachloride or 1,1-dichloro-1-fluoroethane. / Muromachi, Sanehiro; Nakajima, Takahiro; Ohmura, Ryo; Mori, Yasuhiko H.

In: Fluid Phase Equilibria, Vol. 305, No. 2, 25.06.2011, p. 145-151.

Research output: Contribution to journalArticle

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abstract = "This paper reports an attempt at acquiring phase-equilibrium pressure (p) versus temperature (T) data for ozone-containing clathrate hydrates formed from an ozone+oxygen gas mixture, a hydrophobic hydrate-forming liquid, and water in the liquid state. For dealing with ozone (O3), a chemically unstable material continuously decaying to oxygen (O2) in the gas phase, we devised a new method, i.e., a modified pressure-search method, to determine the equilibrium p-T conditions while maintaining the ozone concentration in the gas phase nearly constant by repeatedly replacing the contents of the gas phase with a freshly generated O3+O2 mixture. Using carbon tetrachloride (CCl4) as the hydrophobic hydrate-forming liquid, we obtained equilibrium p-T data in the range of 0.167MPa≤p≤0.361MPa and 275.6K≤T≤277.3K in the presence of a gas phase containing O3 at the molar concentration of 6.9±0.8{\%}. We also obtained, for comparison, the corresponding p-T data, using pure O2 gas, instead of the O3+O2 mixture, and the conventional pressure-search method. The two data groups obtained from the O3-containing and O3-free systems, respectively, show simple, mutually consistent p-T relations each well fitted by the Clausius-Clapeyron equation assuming a constant enthalpy of hydrate dissociation. The paper also describes our additional attempt at obtaining equilibrium p-T data using 1,1-dichloro-1-fluoroethane (R141b) as a substitute for CCl4. Because of the partial decomposition of R141b due to the coexistence of O3 and water, however, we obtained only limited data which are tentative in nature.",
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