論文 - 大村　亮

Characterization of the ionic clathrate hydrate of tetra-n-butylammonium acrylate

Sanehiro Muromachi, Masato Kida, Satoshi Takeya, Yoshitaka Yamamoto, Ryo Ohmura

Canadian Journal of Chemistry 93 （ 9 ） 954 - 959 2015年04月

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Molecular dynamics study of guest-host hydrogen bonding in alcohol clathrate hydrates

Masaki Hiratsuka, Ryo Ohmura, Amadeu K Sum, Saman Alavi and Kenji Yasuoka

Physical Chemistry Chemical Physics （Royal Society of Chemistry）  17   12639 - 12647 2015年03月

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Experiments and thermodynamic simulations for continuous separation of CO2 from CH4+CO2 gas mixture utilizing hydrate formation

Shuhei Tomita, Satoru Akatsu, Ryo Ohmura

Applied Energy （Elsevier）  146   104 - 110 2015年03月

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Effect of nitrogen atom substitution in cyclic guests on properties of sH clathrate hydrates

Kazuki Imasato, Kotaro Murayama, Satoshi Takeya, Saman Alavi, Ryo Ohmura

Canadian Journal of Chemistry （National Research Council of Canada）  93 （ 8 ） 906 - 912 2015年03月

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Phase equilibrium for ionic semiclathrate hydrates formed in the system of water + tetra-n-butylammonium bromide pressurized with carbon dioxide

Kobori Takayuki, Muromachi Sanehiro, Ohmura Ryo

Journal of Chemical and Engineering Data 60 （ 2 ） 299 - 303 2015年02月

ISSN  0021-9568

　概要を見る

<p>This paper reports the vapor-liquid-hydrate three phase equilibrium conditions of ionic semiclathrate hydrates formed in the system of water + tetra-n-butylammonium bromide pressurized with carbon dioxide. The three phase equilibrium temperatures were measured in the ranges from 278.8 to 287.4 K of temperature and from 0.05 to 0.45 of mass fraction of tetra-n-butylammonium bromide (w_TBAB). Measurements were performed at the system pressures of 0.3 MPa, 0.6 MPa, and 1 MPa. For the three system pressures, the equilibrium temperatures increased with the increase in w_TBAB for w_TBAB &lt; 0.35 and decreased for w_TBAB &gt; 0.40. The highest equilibrium temperatures were obtained at w_TBAB = 0.35 and 0.40. The equilibrium temperatures of the tetra-n-butylammonium bromide + carbon dioxide hydrates were higher than those of the simple tetra-n-butylammonium bromide hydrates formed under atmospheric pressure. The improvement of the thermodynamic stability of the tetra-n-butylammonium bromide + carbon dioxide hydrates is ascribed to the incorporation of carbon dioxide molecules into the hydrate cages. The data obtained in the present study may be utilized to specify the thermodynamic conditions to form the tetra-n-butylammonium bromide + carbon dioxide hydrates without forming the simple tetra-n-butylammonium hydrates.</p>

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Experimental measurements of carbon dioxide solubility in aqueous tetra-n-butylammonium bromide solutions

Sanehiro Muromachi, Atsushi Shijima, Hiroyuki Miyamoto, Ryo Ohmura

The Journal of Chemical Thermodynamics （Elsevier）  85   94 - 100 2015年01月

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Crystal Growth of Clathrate Hydrate in Flowing Liquid Water System Saturated with Methane Gas

Muhammad Aifaa, Takehide Kodama, and Ryo Ohmura

Crystal Growth & Design （American Chemical Society）  15 （ 2 ） 559 - 563 2015年01月

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SURFACTANT EFFECTS ON CRYSTAL GROWTH OF CLATHRATE HYDRATE AT THE INTERFACE OF WATER AND HYDROPHOBIC-GUEST LIQUID

Makoto Mitarai, Masatoshi Kishimoto, Donguk Suh, and Ryo Ohmura

Crystal Growth & Design （American Chemical Society）  15 （ 1 ） 812 - 821 2015年01月

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Effect of fuel boiling point of pool flame for the flame extinction by CO₂ hydrate

Sugahara Akito, Nakano Hirotaka, Yokomori Takeshi, Ohmura Ryo, Ueda Toshihisa

2015年

　概要を見る

<p>Experimental investigations to extinguish pool flames by CO₂ hydrate powder and dry ice powder have been done. Methanol and 1-hexanol are used as a fuel of pool flames. The boiling point of the methanol, 67.4 °C, is lower than that of the water, while that of the 1-hexanol, 157 °C, is higher than that of the water. A variation in the flame shape to extinction is recorded by a high-speed video camera. Critical mass for extinction, which is defined as a minimum mass of fire extinguishing agent for extinction, extinction time, temperature variation in and above the fuel are measured. In the case of a methanol pool flame, more critical mass of CO₂ hydrate is necessary compared to the dry ice to supply same mass of CO₂ gas. This indicates that the supply of CO₂ gas plays a key role to extinguish the methanol pool flame, which dilutes the methanol gas and weakens the mixing between methanol gas and air. In the case of 1-hexanol, less critical mass of CO₂ hydrate is necessary compared to the dry ice. In this case, the water in CO₂ hydrate dilutes and cools down the 1-hexanol which results in a decrease in the vaporization of the 1-hexanol.</p>

Crystal growth of clathrate hydrates formed with methane + carbon dioxide mixed gas at the gas/liquid interface and in liquid water

Ueno Hiroki, Akiba Hotaka, Akatsu Satoru, Ohmura Ryo

New Journal of Chemistry 39 （ 11 ） 8254 - 8262 2015年

ISSN  1144-0546

　概要を見る

<p>Visual observations of CH₄ + CO₂ hydrate crystal growth formed at the gas/liquid interface and in liquid water presaturated with a mixed gas have been made. The compositions of the CH₄ + CO₂ gaseous mixture were 40:60 and 30:70 for the gas/liquid interface observations, 30:70 and 70:30 for water saturated with the guest gas. The feed gas compositions of the CH₄ and CO₂ gaseous mixture were 40:60 and 30:70 for the gas/liquid interface observations, or 30:70 and 70:30 for liquid water. The crystal morphology of the CH₄ + CO₂ hydrate observed in both feed gas compositions was similar. This may be ascribed to the fact that the molar ratios of CO₂ to CH₄ in the liquid phase ranged from 90:10 to 97:3 due to the greater solubility of CO₂ in water. These results suggest that the crystal morphology of the CH₄ + CO₂ hydrate may be controlled by the guest composition in the liquid phase, not by the feed gas composition. As the system subcooling increased, the shape of the hydrate crystals changed from polygons to sword-like or dendrites. The implications for the process design of the hydrate-based technologies are discussed based on the observations.</p>

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Crystal Growth Behavior of Methane Hydrate in the Presence of Liquid Hydrocarbon

Kazuki Imasato, Hiroki Tokutomi, and Ryo Ohmura

Crystal Growth & Design （American Chemical Society）  15 （ 1 ） 428 - 433 2014年11月

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Anisotropic Lattice Expansion of Structure H Clathrate Hydrates Induced by Help Guest: Experiments and Molecular Dynamics Simulations

Kotaro Murayama, Satoshi Takeya, Saman Alavi and Ryo Ohmura

Journal of Physical Chemistry Part C （American Chemical Society）  118   21323 - 21330 2014年08月

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Natural supersaturation conditions needed for nucleation air clathrate hydrates in deep ice sheets

Tsutomu Uchida, Keita Yasuda, Yuya Oto, Renkai Shen and Ryo Ohmura

Journal of Glaciology （international glaciological society）  60   1111 - 1116 2014年08月

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Guest-induced symmetry lowering of an ionic clathrate material for carbon capture

S. Muromachi, K. A. Udachin, K. Shin, S. Alavi, I. L. Moudrakovski, R.Ohmura and J. A. Ripmeester

Chemical Communications （Royal Society of Chemistry）  50   11476 - 11479 2014年05月

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Vibrational Spectra of Deuterated Methane and Water Molecules in Structure I Clathrate Hydrate from ab initio MD simulation

Masaki Hiratsuka, Ryo Ohmura1, Amadeu K. Sum and Kenji Yasuoka

Molecular Simulation （Taylor & Francis）  Accepted for publicatino 2014年05月

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Increasing molecular O3 storage capacity in a clathrate hydrate

Kazutoshi Shishido, Sanehiro Muromachi, Ryo Nakamura, Satoshi Takeyab and Ryo Ohmura

New Journal of Chemistry （Royal Society of Chemistry）  38   3160 - 3165 2014年05月

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Phase equilibrium and crystallographic structure of clathrate hydrate formed in argon + 2,2-dimethylbutane + water system

Kotaro Murayama, Satoshi Takeya, Ryo Ohmura

Fluid Phase Equilibria （Elsevier）  365 （ 1 ） 64-67 2014年04月

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Clathrate-hydrate formation from a hydrocarbon gas mixture: compositional evolution of formed hydrate during an isobaric semi-batch hydrate-forming operation

Wataru Kondo, Kaoru Ohtsuka, Ryo Ohmura, Satoshi Takeya, and Yasuhiko H. Mori

Applied Energy （Elsevier）  113 （ 1 ） 864-871 2014年04月

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Comparative study of large-scale hydrogen storage technologies: Is hydrate-based storage at advantage over existing technologies?

Makoto Ozaki, Shigeo Tomura, Ryo Ohmura and Yasuhiko H. Mori

International Journal of Hydrogen Energy （Elsevier; International Association for Hydrogen Energy）  39 （ 1 ） 3327-3341 2014年04月

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Characterization of clathrate hydrates formed with CH4 or CO2 plus tetrahydropyran

Kento Iino, Satoshi Takeya, Ryo Ohmura

Fuel （Elsevier）  122 （ 2 ） 270-276 2014年02月

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