Interfacial properties of hydrocarbon/water systems predicted by molecular dynamic simulations

Parisa Naeiji, Tom K. Woo, Saman Alavi, Farshad Varaminian, Ryo Ohmura

研究成果: Article

2 引用 (Scopus)

抄録

The presence of small hydrocarbons is known to reduce the interfacial tension of the gas-water interface, and this phenomenon can affect the formation of the clathrate hydrates of these gases. In this work, the interfacial behavior of the pure methane-, ethane-, and propane-water, and the ternary 90:7:3 mol. % gas mixture of (methane + ethane + propane)-water were studied with molecular dynamics simulations. The interfacial tension, γ, and z-density profiles for the gases and water from simulations of the gas-water systems were determined at the temperatures of 275.15 and 298.15 K, and pressures up to 10 MPa for methane and up to near the experimental saturation pressures of ethane and propane. The goal is to accurately calculate the interfacial tension for the hydrocarbon/water systems and to analyze the molecular behaviors at the interfaces which lead to the observed trends. At the same hydrostatic gas phase pressure, propane, ethane, and methane reduce the gas-water interfacial tension in that order. The local density of the gas molecules at the interface is enhanced relative to the bulk gas, and it was determined that about 13%-20%, 33%-40%, and 54%-59% of the gas molecules in the simulation congregated at the interfaces for the CH 4 -, C 2 H 6 -, and C 3 H 8 -water systems, respectively, at the different simulated hydrostatic pressure ranges. For all gases in the pressure range studied, a complete monolayer of gas had not formed at the water interface. Furthermore, a dynamic equilibrium with fast exchange between molecules at the interface and in the gas phase was observed. For the gas mixture, deviations were observed between total calculated interfacial tension, γ mix , and the "ideal mixture" value, ςx i γ i,pure , calculated from the interfacial tensions of the pure gases, where x i is the mole fraction of each substance in the simulation. Some possible implications of the results on the mechanism of clathrate hydrate formation are discussed.

元の言語English
記事番号114703
ジャーナルJournal of Chemical Physics
150
発行部数11
DOI
出版物ステータスPublished - 2019 3 21

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Hydrocarbons
Molecular dynamics
hydrocarbons
Gases
molecular dynamics
Water
Computer simulation
gases
water
interfacial tension
Surface tension
simulation
Propane
Ethane
propane
ethane
Methane
methane
clathrates
hydrates

ASJC Scopus subject areas

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

これを引用

Interfacial properties of hydrocarbon/water systems predicted by molecular dynamic simulations. / Naeiji, Parisa; Woo, Tom K.; Alavi, Saman; Varaminian, Farshad; Ohmura, Ryo.

:: Journal of Chemical Physics, 巻 150, 番号 11, 114703, 21.03.2019.

研究成果: Article

Naeiji, Parisa ; Woo, Tom K. ; Alavi, Saman ; Varaminian, Farshad ; Ohmura, Ryo. / Interfacial properties of hydrocarbon/water systems predicted by molecular dynamic simulations. :: Journal of Chemical Physics. 2019 ; 巻 150, 番号 11.
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