Understanding effect of structure and stability on transformation of CH4 hydrate to CO2 hydrate

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

doi:10.1016/j.cplett.2016.02.004

Cited by 31 publications

(22 citation statements)

References 38 publications

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“…In earlier preliminary studies [48], we have explored the thermodynamic stability of CH 4 and CO 2 hydrates and its relation to the replacement reaction. According to the change of Gibbs free energy as shown in Fig.…”

Section: Thermodynamic Analysismentioning

confidence: 99%

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

Liu

Yan

et al. 2016

Computational Materials Science

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Section: Thermodynamic Analysismentioning

confidence: 99%

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

Liu

Yan

et al. 2016

Computational Materials Science

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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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“…For example, in 2009, Geng et al [1] found through experiments that CO 2 is more suitable for occupying the water cage during the replacement process. In 2012, Bai et al [2] used molecular dynamics simulation methods to explore the microscopic mechanism of replacing methane hydrate with carbon dioxide; in 2014, the experimental study of Rubén Martos-Villa et al [3] showed that injecting CO 2 underground can convert simple CH 4 hydrates to CO 2 hydrate or CO 2 -CH 4 mixed gas hydrate; in 2016, Liu et al [4] used the first-principles density functional method to calculate the stability of the hydrate. Their results showed that CO 2 -CH 4 mixed gas hydrates are more stable than CH 4 hydrates in deep-sea sediments or permanent frozen land in the soil; in 2019, Wu et al [5] outlined a process for CO 2 replacing methane hydrate from two perspectives of replacement and coexistence and found that the two can coexist (i. e., form CO 2 -CH 4 mixed gas hydrate).In 2020, Kondori et al [6] showed through molecular simulation studies that a mixed gas hydrate with a molecular ratio of 1 : 4 of methane and carbon dioxide can exist stably under conditions of 300 K temperature and 5 MPa pressure.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation Study of N₂/CO₂ Displacement Process of Methane Hydrate

et al. 2020

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In this paper, we construct three kinds of hydrate replacement models: N 2 , CO 2 and N 2-CO 2. The molecular dynamics (MD) method is used to study the dynamic process of N 2-CO 2 replacement for natural gas hydrate. The replacement efficiency of N 2 /CO 2 is simulated, and the influence of gas replacement on the stability of the water cage is assessed. The results show that CH 4 molecules in the driving hydrate are all enriched in the gas-liquid interface or gas region. Compared with the replacement of methane hydrate with CO 2 , when N 2-CO 2 mixed gas is used to replace methane hydrate, the diffusion rate of CO 2 is increased by 2 times, and the replacement efficiency of hydrate is significantly improved. The radial distribution function and free energy calculation results show that although the barrier of the water cage is significantly reduced after replacement, the water molecules in the cage still have difficulty jumping over the free energy barrier compared with the thermal motion energy, so the water cage structure remains highly stable.

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Understanding effect of structure and stability on transformation of CH4 hydrate to CO2 hydrate

Cited by 31 publications

References 38 publications

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

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

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

Molecular Dynamics Simulation Study of N₂/CO₂ Displacement Process of Methane Hydrate

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Understanding effect of structure and stability on transformation of CH4 hydrate to CO2 hydrate

Cited by 31 publications

References 38 publications

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

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

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

Molecular Dynamics Simulation Study of N2/CO2 Displacement Process of Methane Hydrate

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

Molecular Dynamics Simulation Study of N₂/CO₂ Displacement Process of Methane Hydrate