Replacement micro-mechanism of CH4 hydrate by N2/CO2 mixture revealed by ab initio studies

Liu, Jinxiang; Yan, Yujie; Xu, Jiafang; Li, Shujuan; Chen, Gang; Zhang, Jun

doi:10.1016/j.commatsci.2016.06.025

Cited by 43 publications

(35 citation statements)

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“…It is crucial for the stability of the mixed hydrate that CH4 occupies the small cages, and that CO2 occupies the large ones. 145,146 Liu et al 147,148 considered the stable structures of CO2, N2, CH4 and mixed hydrates and computed structural and thermal fluctuations. Their results suggest that to recover most CH4 from methane hydrates, CO2 should occupy the larger cages and N2 the smaller ones.…”

Section: Some Advancements In the Understanding Of Clathrate Hydratesmentioning

confidence: 99%

Clathrate hydrates: recent advances on CH₄ and CO₂ hydrates, and possible new frontiers

Striolo

2019

Molecular Physics

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Gas hydrates continue to attract enormous attention throughout the energy industry, as both a hindrance in conventional production and a substantial unconventional resource. Scientists continue to be fascinated by hydrates because of their peculiar properties, including the ability of sequestering large amounts of hydrophobic gases, unusual thermal transport properties, and unique molecular structures. From a technological point of view, clathrate hydrates offer potential advantages in applications as diverse as natural gas production, carbon sequestration, water desalination and natural gas storage. The communities interested in hydrates span traditional academic disciplines, including earth science, physical chemistry, and petroleum engineering. The studies on this field are equally diverse, including field expeditions to attempt the production of natural gas from hydrate deposits accumulated naturally on the seafloor, to lab-scale studies to attempt to exchange CO2 for the CH4 present in hydrate deposits; from the scale up of water desalination plants to the testing of compounds used to prevent the formation of large hydrate plugs in pipelines; from theoretical studies to understand the stability of hydrates depending on the guest molecules, to molecular simulations to probe nucleation mechanisms. This review highlights a few fundamental questions faced by the research community, with focus on knowledge gaps representing some of the barriers that must be addressed to enable growth in the practical applications of hydrate technology, including natural gas storage, water desalination, CO2-CH4 exchange in hydrate deposits, and prevention of hydrate plugs in conventional energy transportation.

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Section: Some Advancements In the Understanding Of Clathrate Hydratesmentioning

confidence: 99%

Clathrate hydrates: recent advances on CH₄ and CO₂ hydrates, and possible new frontiers

Striolo

2019

Molecular Physics

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“…It has been investigated that the injection of CO 2 into CH 4 hydrate reserves could result in both CO 2 sequestration and CH 4 exploitation simultaneously. − The hydrate equilibrium of CH 4 –CO 2 gas mixture formed after CO 2 injection has been extensively explored to confirm the feasibility of methane recovery by CO 2 swapping method. ,− More recently, Park et al proposed that the injection of CO 2 +N 2 gas mixture was more efficient than pure CO 2 for recovering CH 4 from hydrates; a significant increase of CH 4 recovery efficiency up to 85% was observed. Following reports on the CH 4 recovery by the exchange of CO 2 +N 2 mixture appeared later. − The inclusion of N 2 in the gas exchange process between CO 2 and CH 4 in hydrates could offer an additional control on hydrates equilibria. − To analyze and understand this complex thermodynamic phenomenon, the complete hydrate phase behavior of the CH 4 –N 2 –CO 2 mixture must be investigated to predict the exchange conditions and understand the mechanism occurring in the replacement in a gas hydrate reservoir. Lee et al studied the hydrate phase equilibrium behavior of the CH 4 –N 2 –CO 2 mixture with specific compositions according to the landfill gas characteristics to evaluate whether the landfill gas can be stored and transported in the form of hydrate.…”

Section: Introductionmentioning

confidence: 99%

Hydrate Phase Equilibrium of CH₄+N₂+CO₂ Gas Mixtures and Cage Occupancy Behaviors

Sun

Zhang

et al. 2017

Ind. Eng. Chem. Res.

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Methane, nitrogen, and carbon dioxide coexist after the injection of CO 2 /N 2 mixture into CH 4 hydrate. For a better understanding of CH 4 recovery and CO 2 sequestration by gas exchange involving N 2 , the hydrate phase equilibrium of CH 4 /N 2 /CO 2 ternary gas mixtures in pure water system was determined in a sapphire cell using the pressure-search method under isothermal conditions. The hydrate equilibrium data were analyzed with respect to the concentration of CH 4 and the ratio of N 2 /CO 2 . The cage occupancies of CH 4 , N 2 , and CO 2 were calculated by Chen−Guo hydrate model and CSMHYD program. The result revealed that the cage-specific guest distributions and preferential partitioning of guest molecules in cages were involved in the formation of mixed gas hydrates. The enthalpy of the ternary hydrates was calculated using the Clausius−Clapeyron equation. It was deduced that the enthalpy of the mixed hydrates was changed with the occupancy of CO 2 molecules in large cavities.

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“…At low temperature condition, CHs entrapping oxygen-contained guest molecules are less structurally stable than those containing hydrocarbons or sulfur [17][18][19] . Liu et al 20 conducted molecular dynamics (MD) simulations to study the thermodynamic and kinetic feasibility of replacing CH4 from CHs with N2/CO2 mixtures, and it was found that the replacement of CH4 with N2 and CO2 has a negative Gibbs free energy, however, CO2 molecular substitution in small cages is structurally disadvantageous. In the substitution process, CO2 molecular substitution is dominant in the thermodynamics, while N2 molecular substitution is dominant in the kinetics.…”

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confidence: 99%

Tensile properties of structural I clathrate hydrates: Role of guest—host hydrogen bonding ability

Yue

Shi

et al. 2021

Front. Phys.

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Clathrate hydrates (CHs) are one of the most promising molecular structures in applications of gas capture and storage, and gas separations. Fundamental knowledge of mechanical characteristics of CHs is of crucial importance for assessing gas storage and separations at cold conditions, as well as understanding their stability and formation mechanisms. Here, the tensile mechanical properties of structural I CHs encapsulating a variety of guest species (CH4, NH3, H2S, CH2O, CH3OH, and CH3SH) that have different abilities to form hydrogen (H-) bonds with water molecule are explored by classical molecular dynamics (MD) simulations. All investigated CHs are structurally stable clathrate structures. Basic mechanical properties of CHs including tensile limit and Young's modulus are dominated by the H-bonding ability of host-guest molecules and the guest molecular polarity. CHs containing small CH4, CH2O and H2S guest molecules that possess weak H-bonding ability are mechanically robust clathrate structures and mechanically destabilized via brittle failure on the (1 0 1) plane. However, those entrapping CH3SH, CH3OH, and NH3 that have strong H-bonding ability are mechanically weak molecular structures and mechanically destabilized through ductile failure as a result of gradual global dissociation of clathrate cages.

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Replacement micro-mechanism of CH4 hydrate by N2/CO2 mixture revealed by ab initio studies

Cited by 43 publications

References 50 publications

Clathrate hydrates: recent advances on CH₄ and CO₂ hydrates, and possible new frontiers

Clathrate hydrates: recent advances on CH₄ and CO₂ hydrates, and possible new frontiers

Hydrate Phase Equilibrium of CH₄+N₂+CO₂ Gas Mixtures and Cage Occupancy Behaviors

Tensile properties of structural I clathrate hydrates: Role of guest—host hydrogen bonding ability

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Replacement micro-mechanism of CH4 hydrate by N2/CO2 mixture revealed by ab initio studies

Cited by 43 publications

References 50 publications

Clathrate hydrates: recent advances on CH4 and CO2 hydrates, and possible new frontiers

Clathrate hydrates: recent advances on CH4 and CO2 hydrates, and possible new frontiers

Hydrate Phase Equilibrium of CH4+N2+CO2 Gas Mixtures and Cage Occupancy Behaviors

Tensile properties of structural I clathrate hydrates: Role of guest—host hydrogen bonding ability

Contact Info

Product

Resources

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Clathrate hydrates: recent advances on CH₄ and CO₂ hydrates, and possible new frontiers

Clathrate hydrates: recent advances on CH₄ and CO₂ hydrates, and possible new frontiers

Hydrate Phase Equilibrium of CH₄+N₂+CO₂ Gas Mixtures and Cage Occupancy Behaviors