Raman spectroscopic analyses of the growth process of CO2 hydrates

Uchida, Tsutomu; Takagi, Akira; Kawabata, Junichi; Mae, Shinji; Hondoh, Takeo

doi:10.1016/0196-8904(95)00064-k

Cited by 73 publications

(47 citation statements)

References 2 publications

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“…Therefore, we propose here that the 5 12 cagelike structure is the precrystallization state that induces the bulk hydrate formation, which has been observed in xenon-ice system. [23] CH 4 molecules may play an important role in the formation of these structures.…”

Section: Resultsmentioning

confidence: 92%

“…They found that CH 4 molecules always occupied the 5 12 small cages in both type I and type II structures and that the large cages were mainly occupied by guest molecules larger than CH 4 . Thus, these spectroscopic approaches were applied to the CH 4 -CO 2 mixed gas system to investigate the formation kinetics described above.…”

Section: Resultsmentioning

confidence: 98%

“…[11] The molar ratio of CH 4 over CO 2 in the hydrate phase was lower than that in the vapor, and it varied in proportion to the molar ratio in the vapor phase. Uchida et al [12] used Raman spectroscopy to observe the replacement of CH 4 molecules with CO 2 molecules in the hydrate. Later, Lee et al [13] observed a similar process using NMR.…”

Section: Gasmentioning

confidence: 99%

“…Both CO 2 and CH 4 form the type I clathrate hydrate. In this structure, CH 4 molecules can occupy both large cages (5 12 6 2 : 14-hedron) and small cages (5 12 : 12-hedron), and CO 2 molecules preferably fit in the 5 12 6 2 cages. Both hydrates are stable under sufficiently high pressures or low temperatures.…”

Section: Introductionmentioning

confidence: 98%

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Kinetics and Stability of CH₄–CO₂ Mixed Gas Hydrates during Formation and Long‐Term Storage

Uchida¹,

Ikeda²,

Takeya³

et al. 2005

ChemPhysChem

135

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The formation of CH4-CO2 mixed gas hydrates was observed by measuring the change of vapor-phase composition using gas chromatography and Raman spectroscopy. Preferential consumption of carbon dioxide molecules was found during hydrate formation, which agreed well with thermodynamic calculations. Both Raman spectroscopic analysis and the thermodynamic calculation indicated that the kinetics of this mixed gas hydrate system was controlled by the competition of both molecules to be enclathrated into the hydrate cages. However, the methane molecules were preferentially crystallized in the early stages of hydrate formation when the initial methane concentration was much less than that of carbon dioxide. According to the Roman spectra, pure methane hydrates first formed under this condition. This unique phenomenon suggested that methane molecules play important roles in the hydrate formation process. These mixed gas hydrates were stored at atmospheric pressure and 190 K for over two months to examine the stability of the encaged gases. During storage, CO2 was preferentially released. According to our thermodynamic analysis, this CO2 release was due to the instability of CO2 in the hydrate structure under the storage conditions.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 98%

Section: Gasmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Kinetics and Stability of CH₄–CO₂ Mixed Gas Hydrates during Formation and Long‐Term Storage

Uchida¹,

Ikeda²,

Takeya³

et al. 2005

ChemPhysChem

135

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“…The density of CO 2 hydrates was determined for various occupancies by Teng et al (10) They reported that the density of CO 2 hydrate is influenced by cage occupancy. Uchida et al (11) measured the density of CO 2 hydrates on the basis of Raman spectrum analysis for different hydration numbers.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo Approach to Structure and Thermodynamic Property of CO2 Hydrate

Ota

Ferdows

2005

JSME international journal. Ser. B, Fluids and thermal engineer

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Monte Carlo simulations have been carried out for the clathrate hydrate of CO 2 hydrates. In this study, we investigate the structure and statistical thermodynamic property of CO 2 hydrates at temperatures ranging from 150 to 288 [K] and at a pressure of up to 50 [MPa] under constant temperature and pressure conditions. We have found that the hydrate structure can be maintained at approximately 283 [K]. The thermodynamic property of density reflects the cage occupancy of the guest molecules and enthalpy increases with increasing temperature. Through our MC simulations, we also clarified hydrate and nonhydrate dividing lines by comparing them with other researchers' experimental results.

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Quantifying hydrate solidification front advancing using method of characteristics

2015

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We develop a one‐dimensional analytical solution based on the method of characteristics to explore hydrate formation from gas injection into brine‐saturated sediments within the hydrate stability zone. Our solution includes fully coupled multiphase and multicomponent flow and the associated advective transport in a homogeneous system. Our solution shows that hydrate saturation is controlled by the initial thermodynamic state of the system and changed by the gas fractional flow. Hydrate saturation in gas‐rich systems can be estimated by 1−cl0cle when Darcy flow dominates, where cl0 is the initial mass fraction of salt in brine, and cle is the mass fraction of salt in brine at three‐phase (gas, liquid, and hydrate) equilibrium. Hydrate saturation is constant, gas saturation and gas flux decrease, and liquid saturation and liquid flux increase with the distance from the gas inlet to the hydrate solidification front. The total gas and liquid flux is constant from the gas inlet to the hydrate solidification front and decreases abruptly at the hydrate solidification front due to gas inclusion into the hydrate phase. The advancing velocity of the hydrate solidification front decreases with hydrate saturation at a fixed gas inflow rate. This analytical solution illuminates how hydrate is formed by gas injection (methane, CO2, ethane, propane) at both the laboratory and field scales.

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Raman spectroscopic analyses of the growth process of CO2 hydrates

Cited by 73 publications

References 2 publications

Kinetics and Stability of CH₄–CO₂ Mixed Gas Hydrates during Formation and Long‐Term Storage

Kinetics and Stability of CH₄–CO₂ Mixed Gas Hydrates during Formation and Long‐Term Storage

Monte Carlo Approach to Structure and Thermodynamic Property of CO2 Hydrate

Quantifying hydrate solidification front advancing using method of characteristics

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Raman spectroscopic analyses of the growth process of CO2 hydrates

Cited by 73 publications

References 2 publications

Kinetics and Stability of CH4–CO2 Mixed Gas Hydrates during Formation and Long‐Term Storage

Kinetics and Stability of CH4–CO2 Mixed Gas Hydrates during Formation and Long‐Term Storage

Monte Carlo Approach to Structure and Thermodynamic Property of CO2 Hydrate

Quantifying hydrate solidification front advancing using method of characteristics

Contact Info

Product

Resources

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Kinetics and Stability of CH₄–CO₂ Mixed Gas Hydrates during Formation and Long‐Term Storage

Kinetics and Stability of CH₄–CO₂ Mixed Gas Hydrates during Formation and Long‐Term Storage