Phase Equilibrium and Crystallographic Structures of Clathrate Hydrates Formed in Methane + 2,2-Dimethylpentane + Water System

Kozaki, Takahiro; Takeya, Satoshi; Ohmura, Ryo

doi:10.1021/je800552k

Cited by 9 publications

(5 citation statements)

References 11 publications

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“…The experimental apparatus to prepare these samples is described elsewhere. 32,33 Each sample was prepared by charging the vessel with 25 grams of fine-grained ice powder (1-2 mm size) and 4.7 or 5.0 grams of ethanol, corresponding to mole fractions of ethanol in solution of 0.056 or 0.060, respectively. The vessel containing ice and ethanol was then immersed in the temperaturecontrolled bath and charged with CO 2 gas supplied from a high-pressure cylinder through a pressure-regulating valve until the pressure in the vessel increased to 0.540 MPa.…”

Section: Powder X-ray Diffractionmentioning

confidence: 99%

Synthesis and characterization of clathrate hydrates containing carbon dioxide and ethanol

Makiya

Murakami

Takeya

et al. 2010

Phys. Chem. Chem. Phys.

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This paper reports an experimental study on the formation of a clathrate hydrate containing ethanol as a guest substance together with carbon dioxide. Phase equilibrium measurements in the system of CO(2) + ethanol + water have been performed in the temperature range from 254 K to 268 K. The measured equilibrium pressure at a given temperature below 264 K was lower by 20 kPa to 30 kPa than the corresponding equilibrium pressure of a simple CO(2) hydrate in the system without ethanol. Powder X-ray diffraction measurements indicated that the hydrate formed is structure I. This crystallographic structure is the same as that of simple CO(2) hydrate. However, the lattice constant of the hydrate formed in the system with ethanol was determined to be 11.8577(5) A at 113 K, which is larger than the corresponding lattice constant (11.8434(8) A) of simple CO(2) hydrate at the same temperature. These experimental results strongly suggest the formation of a new hydrate containing both ethanol and CO(2) as guest substances, thus contributing toward future applications considering CO(2) hydrates. To further understand the inclusion of ethanol molecules in the structure I hydrate and the measured increase in the crystal lattice constant, molecular dynamics simulations were performed to support the experimental results.

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Section: Powder X-ray Diffractionmentioning

confidence: 99%

Synthesis and characterization of clathrate hydrates containing carbon dioxide and ethanol

Makiya

Murakami

Takeya

et al. 2010

Phys. Chem. Chem. Phys.

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“…The apparatus for phase equilibrium measurements was the same as that employed in our previous study. 15 The test cell for the four-phase equilibrium, water-rich liquid (L w ) + hydrate (H) + methane-rich vapor (V) + LMGS (L g ) measurements was a stainless steel cylindrical vessel with inner dimensions of 50 mm in diameter and 120 mm in height. In the vessel, a magnetic stirrer provided agitation to the fluid at 400 rpm.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

Phase Equilibrium for Structure H Hydrates Formed with Methane plus Cycloheptane, Cycloheptanone, or Oxacycloheptane

et al. 2010

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Pressure and temperature conditions for the four-phase equilibrium in systems that include liquid water, structure H hydrate, methane gas, and liquid hydrocarbon substances (cycloheptane, cycloheptanone, or oxacycloheptane) were measured over the temperature range (273.5 to 284.1) K. The measurements indicate that, at 274 K, the equilibrium pressures of the systems with cycloheptane, cycloheptanone, and oxacycloheptane were lower by (1.6, 1.3, and 1.5) MPa, respectively, than those of the structure I methane hydrates in equilibrium with liquid water and methane vapor. Powder X-ray diffraction measurements of the formed hydrate samples confirmed structure H hydrates.

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“…L w –H–G–L HC equilibria for the methane + 2,2-dimethylpentane + water system. Symbols represent experimental data . Solid curve: Prediction of the model using the PR EoS for modeling of the gas phase.…”

Section: Resultsmentioning

confidence: 99%

“…Symbols represent experimental data. 27 Solid curve: Prediction of the model using the PR 16 EoS for modeling of the gas phase. Dashed curve: Prediction of the model using the SRK 17 EoS for modeling of the gas phase.…”

Section: Thermodynamic Modelmentioning

confidence: 99%

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Thermodynamic Model for the Prediction of Equilibrium Conditions of Clathrate Hydrates of Methane + Water-Soluble or -Insoluble Hydrate Former

Illbeigi

Fazlali

Mohammadi

2011

Ind. Eng. Chem. Res.

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International audienceIn this communication, equilibrium conditions of clathrate hydrates of cyclopentane, cylcohexane, acetone, or 1,4- dioxane þ methane, which form structure II, and 1,1-dimethylcyclohexane, 2,2-dimethylpentane, methylcyclohexane, or cis-1,2- dimethylcyclohexane þ methane, which form structure H, are modeled. The thermodynamic model is based on the van der Waals-Platteeuw solid solution theory combined with an equation of state and activity model. The Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) equations of state with random mixing rules are used to model the gas phase, while the UNIFAC method is used to model the liquid phase(s). It is shown that the use of the PR equation of state leads to better predictions of hydrate equilibriumconditions of the aforementioned water-insoluble heavy hydrocarbons, while the use of the SRK equation of state causes better predictions of hydrate equilibrium conditions of the latter water-soluble hydrate formers

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Phase Equilibrium and Crystallographic Structures of Clathrate Hydrates Formed in Methane + 2,2-Dimethylpentane + Water System

Cited by 9 publications

References 11 publications

Synthesis and characterization of clathrate hydrates containing carbon dioxide and ethanol

Synthesis and characterization of clathrate hydrates containing carbon dioxide and ethanol

Phase Equilibrium for Structure H Hydrates Formed with Methane plus Cycloheptane, Cycloheptanone, or Oxacycloheptane

Thermodynamic Model for the Prediction of Equilibrium Conditions of Clathrate Hydrates of Methane + Water-Soluble or -Insoluble Hydrate Former

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