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Microscale Processes and Dynamics during CH4–CO2 Guest-Molecule Exchange in Gas Hydrates. ENERGIES 2021. [DOI: 10.3390/en14061763] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The exchange of CH4 by CO2 in gas hydrates is of interest for the production of natural gas from methane hydrate with net zero climate gas balance, and for managing risks that are related to sediment destabilization and mobilization after gas-hydrate dissociation. Several experimental studies on the dynamics and efficiency of the process exist, but the results seem to be partly inconsistent. We used confocal Raman spectroscopy to map an area of several tens to hundreds µm of a CH4 hydrate sample during its exposure to liquid and gaseous CO2. On this scale, we could identify and follow different processes in the sample that occur in parallel. Next to guest-molecule exchange, gas-hydrate dissociation also contributes to the release of CH4. During our examination period, about 50% of the CO2 was bound by exchange for CH4 molecules, while the other half was bound by new formation of CO2 hydrates. We evaluated single gas-hydrate grains with confirmed gas exchange and applied a diffusion equation to quantify the process. Obtained diffusion coefficients are in the range of 10−13–10−18 m2/s. We propose to use this analytical diffusion equation for a simple and robust modeling of CH4 production by guest-molecule exchange and to combine it with an additional term for gas-hydrate dissociation.
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2
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New Insights on a µm-Scale into the Transformation Process of CH4 Hydrates to CO2-Rich Mixed Hydrates. ENERGIES 2020. [DOI: 10.3390/en13225908] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The global occurrences of natural gas hydrates lead to the conclusion that tremendous amounts of hydrocarbons are bonded in these hydrate-bearing sediments, serving as a potential energy resource. For the release of the hydrate-bonded CH4 from these reservoirs, different production methods have been developed during the last decades. Among them, the chemical stimulation via injection of CO2 is considered as carbon neutral on the basis of the assumption that the hydrate-bonded CH4 is replaced by CO2. For the investigation of the replacement process of hydrate-bonded CH4 with CO2 on a µm-scale, we performed time-resolved in situ Raman spectroscopic measurements combined with microscopic observations, exposing the CH4 hydrates to a CO2 gas phase at 3.2 MPa and 274 K. Single-point Raman measurements, line scans and Raman maps were taken from the hydrate phase. Measurements were performed continuously at defined depths from the surface into the core of several hydrate crystals. Additionally, the changes in composition in the gas phase were recorded. The results clearly indicated the incorporation of CO2 into the hydrate phase with a concentration gradient from the surface to the core of the hydrate particle, supporting the shrinking core model. Microscopic observations, however, indicated that all the crystals changed their surface morphology when exposed to the CO2 gas. Some crystals of the initial CH4 hydrate phase grew or were maintained while at the same time other crystals decreased in sizes and even disappeared over time. This observation suggested a reformation process similar to Ostwald ripening rather than an exchange of molecules in already existing hydrate structures. The experimental results from this work are presented and discussed in consideration of the existing models, providing new insights on a µm-scale into the transformation process of CH4 hydrates to CO2-rich mixed hydrates.
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Ren JJ, Lu ZL, Long Z, Liang D. Experimental study on the kinetic effect of N-butyl- N-methylpyrrolidinium tetrafluoroborate and poly( N-vinyl-caprolactam) on CH 4 hydrate formation. RSC Adv 2020; 10:15320-15327. [PMID: 35495463 PMCID: PMC9052332 DOI: 10.1039/c9ra10998f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Accepted: 03/31/2020] [Indexed: 11/21/2022] Open
Abstract
In this work, a series of experiments were carried out to study the kinetic inhibition performance of N-butyl-N-methylpyrrolidinium tetrafluoroborate ([BMP][BF4]), poly(N-vinylcaprolactam) (PVCap) and compound inhibitor systems on methane hydrate from both macroscopic and microscopic perspectives. In the macroscopic experiments, the influence of the concentration, the ratio of inhibitors, the subcooling on the induction time and gas consumption rate of methane hydrate were studied. The results indicated that [BMP][BF4] could inhibit the growth rate of CH4 hydrate, but failed to delay the nucleation. An improved inhibitory effect was observed by combining [BMP][BF4] and PVCap, and the optimal ratio of the two inhibitors was obtained to gain the best inhibition performance. Furthermore, the microstructure and morphology of methane hydrate crystals formed in different inhibitor systems were investigated through powder X-ray diffraction (PXRD), Raman spectroscopy and scanning electron cryomicroscopy (Cryo-SEM) methods. It was found that [BMP][BF4] and PVCap had different influences on the large cage occupancy by CH4 and the morphology of methane hydrate.
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Affiliation(s)
- Jun-Jie Ren
- CAS Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China .,Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development Guangzhou Guangdong 510640 China.,Guangzhou Center for Gas Hydrate Research, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China.,University of Chinese Academy of Sciences Beijing 100049 China
| | - Zhi-Lin Lu
- CAS Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China .,Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development Guangzhou Guangdong 510640 China.,Guangzhou Center for Gas Hydrate Research, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China.,Nano Science and Technology Institute, University of Science and Technology of China Suzhou Jiangsu 215123 China
| | - Zhen Long
- CAS Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China .,Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development Guangzhou Guangdong 510640 China.,Guangzhou Center for Gas Hydrate Research, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China
| | - Deqing Liang
- CAS Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China .,Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development Guangzhou Guangdong 510640 China.,Guangzhou Center for Gas Hydrate Research, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China
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4
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The Effect of CO2 Partial Pressure on CH4 Recovery in CH4-CO2 Swap with Simulated IGCC Syngas. ENERGIES 2020. [DOI: 10.3390/en13051017] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To investigate the influence of CO2 partial pressure on efficiency of CH4-CO2 swap from natural gas hydrates (NGHs), the replacement of CH4 from natural gas hydrate (NGH) is carried out with simulated Integrated Gasification Combined Cycle (IGCC) syngas under different pressures, and the gas chromatography (GC), in-situ Raman, and powder X-ray diffraction (PXRD) are employed to analyze the hydrate compositions and hydrate structures. The results show that with the P-T (pressure and temperature) condition shifting from that above the hydrate equilibrium curve of IGCC syngas to that below the hydrate equilibrium curve of IGCC syngas, the rate of CH4 recovery drastically rises from 32% to 71%. The presence of water can be clearly observed when P-T condition is above the hydrate equilibrium curve of IGCC syngas; however the presence of water only occurs at the interface between gas phase and hydrate phase. No H2 is found to present in the final hydrate phase at the end of process of CH4-CO2 swap with IGCC syngas.
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Hassanpouryouzband A, Joonaki E, Vasheghani Farahani M, Takeya S, Ruppel C, Yang J, English NJ, Schicks JM, Edlmann K, Mehrabian H, Aman ZM, Tohidi B. Gas hydrates in sustainable chemistry. Chem Soc Rev 2020; 49:5225-5309. [DOI: 10.1039/c8cs00989a] [Citation(s) in RCA: 247] [Impact Index Per Article: 61.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This review includes the current state of the art understanding and advances in technical developments about various fields of gas hydrates, which are combined with expert perspectives and analyses.
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Affiliation(s)
- Aliakbar Hassanpouryouzband
- Hydrates, Flow Assurance & Phase Equilibria Research Group
- Institute of GeoEnergy Engineering
- School of Energy
- Geoscience, Infrastructure and Society
- Heriot-Watt University
| | - Edris Joonaki
- Hydrates, Flow Assurance & Phase Equilibria Research Group
- Institute of GeoEnergy Engineering
- School of Energy
- Geoscience, Infrastructure and Society
- Heriot-Watt University
| | - Mehrdad Vasheghani Farahani
- Hydrates, Flow Assurance & Phase Equilibria Research Group
- Institute of GeoEnergy Engineering
- School of Energy
- Geoscience, Infrastructure and Society
- Heriot-Watt University
| | - Satoshi Takeya
- National Institute of Advanced Industrial Science and Technology (AIST)
- Tsukuba 305-8565
- Japan
| | | | - Jinhai Yang
- Hydrates, Flow Assurance & Phase Equilibria Research Group
- Institute of GeoEnergy Engineering
- School of Energy
- Geoscience, Infrastructure and Society
- Heriot-Watt University
| | - Niall J. English
- School of Chemical and Bioprocess Engineering
- University College Dublin
- Dublin 4
- Ireland
| | | | - Katriona Edlmann
- School of Geosciences
- University of Edinburgh
- Grant Institute
- Edinburgh
- UK
| | - Hadi Mehrabian
- Department of Chemical Engineering
- Massachusetts Institute of Technology
- Cambridge
- USA
| | - Zachary M. Aman
- Fluid Science & Resources
- School of Engineering
- University of Western Australia
- Perth
- Australia
| | - Bahman Tohidi
- Hydrates, Flow Assurance & Phase Equilibria Research Group
- Institute of GeoEnergy Engineering
- School of Energy
- Geoscience, Infrastructure and Society
- Heriot-Watt University
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6
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Striolo A. Clathrate hydrates: recent advances on CH4 and CO2 hydrates, and possible new frontiers. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1646436] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Alberto Striolo
- Department of Chemical Engineering, University College London, London, UK
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7
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Tupsakhare SS, Fitzgerald GC, Castaldi MJ. Thermally Assisted Dissociation of Methane Hydrates and the Impact of CO2 Injection. Ind Eng Chem Res 2016. [DOI: 10.1021/acs.iecr.6b02509] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Swanand S. Tupsakhare
- Chemical
Engineering Department, City College, City University of New York, New York, New York 10031, United States
| | - Garrett C. Fitzgerald
- Rocky Mountain
Institute, 22830 Two Rivers Road, Basalt, Colorado 81621, United States
| | - Marco J. Castaldi
- Chemical
Engineering Department, City College, City University of New York, New York, New York 10031, United States
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8
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Kvamme B. Feasibility of simultaneous CO2 storage and CH4 production from natural gas hydrate using mixtures of CO2 and N2. CAN J CHEM 2015. [DOI: 10.1139/cjc-2014-0501] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Production of natural gas from hydrate using carbon dioxide allows for a win-win situation in which carbon dioxide can be safely stored in hydrate form while releasing natural gas from in situ hydrate. This concept has been verified experimentally and theoretically in different laboratories worldwide, and lately also in a pilot plant in Alaska. The use of carbon dioxide mixed with nitrogen has the advantage of higher gas permeability. Blocking of flow channels due to formation of new hydrate from injected gas will also be less compared to injection of pure carbon dioxide. The fastest mechanism for conversion involves the formation of a new hydrate from free pore water and the injected gas. As a consequence of the first and second laws of thermodynamics, the most stable hydrate will form first in a dynamic situation, in which carbon dioxide will dominate the first hydrates formed from water and carbon dioxide / nitrogen mixtures. This selective formation process is further enhanced by favorable selective adsorption of carbon dioxide onto mineral surfaces as well as onto liquid water surfaces, which facilitates efficient heterogeneous hydrate nucleation. In this work we examine limitations of hydrate stability as function of gradually decreasing content of carbon dioxide. It is argued that if the flux of gas through the reservoir is high enough to prevent the gas from being depleted for carbon dioxide prior to subsequent supply of new gas, then the combined carbon dioxide storage and natural gas production is still feasible. Otherwise the residual gas dominated by nitrogen will still dissociate the methane hydrate, if the released in situ CH4 from hydrate does not mix in with the gas but escapes through separate flow channels by buoyancy. The ratio of nitrogen to carbon dioxide in such mixtures is therefore a sensitive balance between flow rates and formation rates of new carbon dioxide dominated hydrate. Hydrate instability due to undersaturations of hydrate formers have not been discussed in this work but might add additional instability aspects.
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Affiliation(s)
- Bjørn Kvamme
- Department of Physics and Technology, University of Bergen, Allegaten 55, 5007 Bergen, Norway
- Department of Physics and Technology, University of Bergen, Allegaten 55, 5007 Bergen, Norway
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Lee Y, Kim Y, Seo Y. Enhanced CH₄ Recovery Induced via Structural Transformation in the CH₄/CO₂ Replacement That Occurs in sH Hydrates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:8899-8906. [PMID: 26107753 DOI: 10.1021/acs.est.5b01640] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The CH4/CO2 replacement that occurs in sH hydrates is investigated, with a primary focus on the enhanced CH4 recovery induced via structural transformation with a CO2 injection. In this study, neohexane (NH) is used as a liquid hydrocarbon guest in the sH hydrates. Direct thermodynamic measurements and spectroscopic identification are investigated to reveal the replacement process for recovering CH4 and simultaneously sequestering CO2 in the sH (CH4 + NH) hydrate. The hydrate phase behavior and the (13)C NMR and Raman spectroscopy results of the CH4 + CO2 + NH systems demonstrate that CO2 functions as a coguest of sH hydrates in CH4-rich conditions, and that the structural transition of sH to sI hydrates occurs in CO2-rich conditions. CO2 molecules are found to preferentially occupy the medium 4(3)5(6)6(3) cages of sH hydrates or the large 5(12)6(2) cages of sI hydrates during the replacement. Due to the favorable structural transition and resulting re-establishment of guest distributions, approximately 88% of the CH4 is recoverable from sH (CH4 + NH) hydrates with a CO2 injection. The hydrate dissociation and subsequent reformation caused by the structural transformation of sH to sI is also confirmed using a high-pressure microdifferential scanning calorimeter through the detection of the significant heat flows generated during the replacement.
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Affiliation(s)
- Yohan Lee
- School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea
| | - Yunju Kim
- School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea
| | - Yongwon Seo
- School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea
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10
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Cha M, Shin K, Lee H, Moudrakovski IL, Ripmeester JA, Seo Y. Kinetics of methane hydrate replacement with carbon dioxide and nitrogen gas mixture using in situ NMR spectroscopy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:1964-71. [PMID: 25565018 DOI: 10.1021/es504888n] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In this study, the kinetics of methane replacement with carbon dioxide and nitrogen gas in methane gas hydrate prepared in porous silica gel matrices has been studied by in situ (1)H and (13)C NMR spectroscopy. The replacement process was monitored by in situ (1)H NMR spectra, where about 42 mol % of the methane in the hydrate cages was replaced in 65 h. Large amounts of free water were not observed during the replacement process, indicating a spontaneous replacement reaction upon exposing methane hydrate to carbon dioxide and nitrogen gas mixture. From in situ (13)C NMR spectra, we confirmed that the replacement ratio was slightly higher in small cages, but due to the composition of structure I hydrate, the amount of methane evolved from the large cages was larger than that of the small cages. Compositional analysis of vapor and hydrate phases was also carried out after the replacement reaction ceased. Notably, the composition changes in hydrate phases after the replacement reaction would be affected by the difference in the chemical potential between the vapor phase and hydrate surface rather than a pore size effect. These results suggest that the replacement technique provides methane recovery as well as stabilization of the resulting carbon dioxide hydrate phase without melting.
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Affiliation(s)
- Minjun Cha
- Department of Energy and Resources Engineering, Kangwon National University , 1 Kangwondaehak-gil, Chuncheon-si, Gangwon-do 200-701, Republic of Korea
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11
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Lee S, Lee Y, Lee J, Lee H, Seo Y. Experimental verification of methane-carbon dioxide replacement in natural gas hydrates using a differential scanning calorimeter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:13184-13190. [PMID: 24175633 DOI: 10.1021/es403542z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The methane (CH4) - carbon dioxide (CO2) swapping phenomenon in naturally occurring gas hydrates is regarded as an attractive method of CO2 sequestration and CH4 recovery. In this study, a high pressure microdifferential scanning calorimeter (HP μ-DSC) was used to monitor and quantify the CH4 - CO2 replacement in the gas hydrate structure. The HP μ-DSC provided reliable measurements of the hydrate dissociation equilibrium and hydrate heat of dissociation for the pure and mixed gas hydrates. The hydrate dissociation equilibrium data obtained from the endothermic thermograms of the replaced gas hydrates indicate that at least 60% of CH4 is recoverable after reaction with CO2, which is consistent with the result obtained via direct dissociation of the replaced gas hydrates. The heat of dissociation values of the CH4 + CO2 hydrates were between that of the pure CH4 hydrate and that of the pure CO2 hydrate, and the values increased as the CO2 compositions in the hydrate phase increased. By monitoring the heat flows from the HP μ-DSC, it was found that the noticeable dissociation or formation of a gas hydrate was not detected during the CH4 - CO2 replacement process, which indicates that a substantial portion of CH4 hydrate does not dissociate into liquid water or ice and then forms the CH4 + CO2 hydrate. This study provides the first experimental evidence using a DSC to reveal that the conversion of the CH4 hydrate to the CH4 + CO2 hydrate occurs without significant hydrate dissociation.
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Affiliation(s)
- Seungmin Lee
- Offshore Plant Resources R&D Center, Korea Institute of Industrial Technology , Busan 618-230, Republic of Korea
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12
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Schicks JM, Luzi-Helbing M. Cage occupancy and structural changes during hydrate formation from initial stages to resulting hydrate phase. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 115:528-536. [PMID: 23871981 DOI: 10.1016/j.saa.2013.06.065] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 06/11/2013] [Accepted: 06/19/2013] [Indexed: 06/02/2023]
Abstract
Hydrate formation processes and kinetics are still not sufficiently understood on a molecular level based on experimental data. In particular, the cavity formation and occupancy during the initial formation and growth processes of mixed gas hydrates are rarely investigated. In this study, we present the results of our time-depending Raman spectroscopic measurements during the formation of hydrates from ice and gases or gas mixtures such as CH4, CH4-CO2, CH4-H2S, CH4-C3H8, CH4-iso-C4H10, and CH4-neo-C5H12 at constant pressure and temperature conditions and constant composition of the feed gas phase. All investigated systems in this study show the incorporation of CH4 into the 5(12) cavities as first step in the initial stages of hydrate formation. Furthermore, the results imply that the initial hydrate phases differ from the resulting hydrate phase having reached a steady state regarding the occupancy and ratio of the small and large cavities of the hydrate.
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Affiliation(s)
- Judith M Schicks
- Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Section 4.2: Inorganic and Isotope Geochemistry, Telegrafenberg, 14473 Potsdam, Germany.
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The Driving Forces of Guest Substitution in Gas Hydrates—A Laser Raman Study on CH4-CO2 Exchange in the Presence of Impurities. ENERGIES 2012. [DOI: 10.3390/en5020420] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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