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Liu L, Guan D, Lu Y, Sun M, Liu Y, Zhao J, Yang L. A Molecular Dynamics Study on Xe/Kr Separation Mechanisms Using Crystal Growth Method. ACS OMEGA 2024; 9:25822-25831. [PMID: 38911791 PMCID: PMC11191100 DOI: 10.1021/acsomega.4c00108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 03/31/2024] [Accepted: 05/23/2024] [Indexed: 06/25/2024]
Abstract
The separation of xenon/krypton gas mixtures is a valuable but challenging endeavor in the gas industry due to their similar physical characteristics and closely sized molecules. To address this, we investigated the effectiveness of the hydrate-based gas separation method for mixed Xe-Kr gas via molecular dynamics (MD) simulations. The formation process of hydrates facilitates the encapsulation of guest molecules within hydrate cages, offering a potential strategy for gas separation. Higher temperatures and pressures are advantageous for accelerating the hydrate growth rate. The final occupancy of guest molecules and empty cages within 512, 51264, and all hydrate cages were thoroughly examined. An increase in the pressure and temperature enhanced the occupancy rates of Xe in both 512 and 51264 cages, whereas elevated pressure alone improved the occupancy of Kr in 51264 cages. However, the impact of temperature and pressure on Kr occupancy within 512 cages was found to be minimal. Elevated temperature and pressure resulted in a reduced occupancy of empty cages. Predominantly, 51264 cages were occupied by Xe, whereas Kr showed a propensity to occupy the 512 cages. With increasing simulated pressure, the final occupancy of Xe molecules in all cages rose from 0.37 to 0.41 for simulations at 260 K, while the final occupancy of empty cages decreased from 0.24 to 0.2.
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Affiliation(s)
- Liangliang Liu
- Shenyang
Aircraft Design Institute Shenyang 110042, China
| | - Dawei Guan
- Key
Laboratory of Ocean Energy Utilization and Energy Conservation of
Ministry of Education, Dalian University
of Technology, Dalian 116024, China
| | - Yi Lu
- Shenyang
Aircraft Design Institute Shenyang 110042, China
| | - Mingrui Sun
- Key
Laboratory of Ocean Energy Utilization and Energy Conservation of
Ministry of Education, Dalian University
of Technology, Dalian 116024, China
| | - Yu Liu
- Key
Laboratory of Ocean Energy Utilization and Energy Conservation of
Ministry of Education, Dalian University
of Technology, Dalian 116024, China
| | - Jiafei Zhao
- Key
Laboratory of Ocean Energy Utilization and Energy Conservation of
Ministry of Education, Dalian University
of Technology, Dalian 116024, China
| | - Lei Yang
- Key
Laboratory of Ocean Energy Utilization and Energy Conservation of
Ministry of Education, Dalian University
of Technology, Dalian 116024, China
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2
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Alavi S, Moudrakovski IL, Ratcliffe CI, Ripmeester JA. Unusual species of methane hydrate detected in nanoporous media using solid state 13C NMR. J Chem Phys 2024; 160:214709. [PMID: 38832748 DOI: 10.1063/5.0204109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 05/14/2024] [Indexed: 06/05/2024] Open
Abstract
Methane is considered to be a cubic structure I (CS-I) clathrate hydrate former, although in a number of instances, small amounts of structure II (CS-II) clathrate hydrate have been transiently observed as well. In this work, solid-state magic angle spinning 13C NMR spectra of methane hydrate formed at low temperatures inside silica-based nanoporous materials with pores in the range of 3.8-20.0 nm (CPG-20, Vycor, and MCM-41) show methane in several different environments. In addition to methane encapsulated in the dodecahedral 512 (D) and tetrakaidecahedral 51262 (T) cages typical of the CS-I clathrate hydrate phase, methane guests in pentakaidecahedral 51263 (P) and hexakaidecahedral 51264 (H) cages are also identified, and these appear to be stabilized for extended periods of time. The ratio of methane guests among the D and T cages determined from the line intensities is significantly different from that of bulk CS-I samples and indicates that both CS-I and CS-II are present as the dominant species. This is the first observation of methane in P cages, and the possible structures in which they could be present are discussed. Broad and relatively strong methane peaks, which are also observed in the spectra, can be related to methane dissolved in an amorphous component of water adjacent to the pore walls. Nanoconfinement and interaction with the pore walls clearly have a strong influence on the hydrate formed and may reflect species present in the early stages of hydrate growth.
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Affiliation(s)
- Saman Alavi
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Igor L Moudrakovski
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | | | - John A Ripmeester
- National Research Council of Canada, 100 Sussex Dr., Ottawa, Ontario K1N 5A2, Canada
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3
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Lin Y, Zhou Z, Song Z, Shi Q, Hao Y, Fu Y, Li T, Zhang Z, Wu J. Insights into the mechanical stability of tetrahydrofuran hydrates from experimental, machine learning, and molecular dynamics perspectives. NANOSCALE 2024; 16:6296-6308. [PMID: 38463012 DOI: 10.1039/d3nr04940j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Natural gas hydrates (NGHs) hold immense potential as a future energy resource and for sustainable applications such as gas capture and storage. Due to the challenging formation conditions, however, their mechanical properties remain poorly understood. Herein, the mechanical characteristics of tetrahydrofuran (THF) hydrates, a proxy for methane hydrates, were investigated at different ice contents, strain rates, and temperatures using uniaxial compressive experiments. The results unveil a distinct behavior in the peak strength of THF hydrates with a varying ice content, strain rate and temperature, exhibiting an increase as the strain rate and temperature decrease, in contrast to the peak strength-strain rate relationship observed in polycrystalline ice. Based on the experimental data, four machine learning (ML) models including extreme gradient boosting (XGboost), multilayer perceptron (MLP), gradient boosting decision tree (GBDT) and decision tree (DT) were developed to predict the peak strength. The XGboost model demonstrates superior predictive performance, emphasizing the significant influence of ice content and temperature on the peak strength of hydrates. Furthermore, molecular dynamics (MD) simulations were employed to gain insights into the dissociation and formation processes of clathrate cages, as well as phase transitions and amorphization occurring at grain boundaries (GBs) involving diverse unconventional clathrate cages, including 51265, 4151062, 4151064, 425861 and 425862, with 425861 and 425862 cages being predominant. This study enhances our understanding of the mechanical properties and deformation mechanisms of hydrates and provides a ML-based predictive framework for estimating the compressive strength of hydrates under diverse coupling conditions. The findings have significant implications for stability assessments of NGHs and the exploitation of NGH resources.
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Affiliation(s)
- Yanwen Lin
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, PR China.
- Key Laboratory of Marine Materials and Related Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, PR China
| | - Ziyue Zhou
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, PR China.
| | - Zixuan Song
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, PR China.
| | - Qiao Shi
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, PR China.
| | - Yongchao Hao
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, PR China.
| | - Yuequn Fu
- PoreLab, the Njord Centre, Department of Physics, University of Oslo, Oslo 0371, Norway
| | - Tong Li
- Key Laboratory of Marine Materials and Related Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, PR China
- Key Laboratory of Icing and Anti/De-icing, China Aerodynamics Research and Development Center, Mianyang Sichuan 621000, China
| | - Zhisen Zhang
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, PR China.
| | - Jianyang Wu
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, PR China.
- NTNU Nanomechanical Lab, Norwegian University of Science and Technology (NTNU), Trondheim 7491, Norway
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Walsh MR. Comparing brute force to transition path sampling for gas hydrate nucleation with a flat interface: comments on time reversal symmetry. Phys Chem Chem Phys 2024; 26:5762-5772. [PMID: 38214888 DOI: 10.1039/d3cp05059a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
Fluid to solid nucleation is often investigated with the rare event method transition path sampling (TPS). I claim that the inherent irreversibility of solid nucleation, even at stationary conditions, calls into question TPS's applicability for determining solid nucleation mechanisms, especially for pre-critical behavior. Even when applied to a phenomenon which displays time reversal asymmetry like solid nucleation, TPS is a good means of exploring phase space and giving trends in post-critical structure, and its ability to facilitate nucleation rate and free energy calculations remains outstanding. Forward-only splitting and ratcheting methods such as forward flux sampling are more attractive for understanding nucleation mechanisms as they do not require time reversal symmetry, but at low driving forces may suffer from the same limitations as brute force: they may never make it to the first ratchet. Here I briefly summarize the TPS method and gas hydrate nucleation simulation literature, focusing on topics within both to facilitate a comparison of brute force hydrate nucleation to transition path sampling of hydrate nucleation. Perhaps anecdotally, the brute force technique results in more crystalline trajectories despite having higher driving forces than TPS. I maintain this difference is because of the inherent irreversibility of hydrate nucleation, meaning its pre-critical behavior cannot accurately be determined by the melting trajectories that comprise approximately half of the configurations in TPS's path ensemble.
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5
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Wang L, Kusalik PG. Understanding why constant energy or constant temperature may affect nucleation behavior in MD simulations: A study of gas hydrate nucleation. J Chem Phys 2023; 159:184501. [PMID: 37947514 DOI: 10.1063/5.0169669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 10/18/2023] [Indexed: 11/12/2023] Open
Abstract
Molecular dynamics simulations have been widely used in exploring the nucleation behavior of many systems, including gas hydrates. Gas hydrates are ice-like solids in which gas molecules are trapped in water cages. During hydrate formation, a considerable amount of heat is released, and previous work has reported that the choice of temperature control scheme may affect the behavior of hydrate formation. The origins of this effect have remained an open question. To address this question, extensive NVE simulations and thermostatted (NPT and NVT) simulations with different temperature coupling strengths have been performed and compared for systems where a water nanodroplet is immersed in a H2S liquid. Detailed analysis of the hydrate structures and their mechanisms of formation has been carried out. Slower nucleation rates in NVE simulations in comparison to NPT simulations have been observed in agreement with previous studies. Probability distributions for various temperature measures along with their spatial distributions have been examined. Interestingly, a comparison of these temperature distributions reveals a small yet noticeable difference in the widths of the distributions for water. The somewhat reduced fluctuations in the temperature for the water species in the NVE simulations appear to be responsible for reducing the hydrate nucleation rate. We further conjecture that the NVE-impeded nucleation rate may be the result of the finite size of the surroundings (here the liquid H2S portion of the system). Additionally, a local spatial temperature gradient arising from the heat released during hydrate formation could not be detected.
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Affiliation(s)
- Lei Wang
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Peter G Kusalik
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
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6
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Li L, Wang X, Yan Y, Francisco JS, Zhang J, Zeng XC, Zhong J. Resolving Temperature-Dependent Hydrate Nucleation Pathway: The Role of "Transition Layer". J Am Chem Soc 2023; 145:24166-24174. [PMID: 37874937 DOI: 10.1021/jacs.3c08246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Understanding the nucleation of natural gas hydrate (NGH) at different conditions has important implications to NGH recovery and other industrial applications, such as gas storage and separation. Herein, vast numbers of hydrate nucleation events are traced via molecular dynamics (MD) simulations at different degrees of supercooling (or driving forces). Specifically, to precisely characterize a hydrate nucleus from an aqueous system during the MD simulation, we develop an evolutionary order parameter (OP) to recognize the nucleus size and shape. Subsequently, the free energy landscapes of hydrate during nucleation are explored by using the newly developed OP. The results suggest that at 270 K (or 0.92 Tm supercooling, where Tm is the melting point), the near-rounded nucleus prevails during the nucleation, as described from the classical nucleation theory. In contrast, at relatively strong driving forces of 0.85 and 0.88 Tm, nonclassical nucleation events arise. Specifically, the pathway toward an elongated nucleus becomes as important as the pathway toward a near-rounded nucleus. To explain the distinct nucleation phenomena at different supercoolings, a notion of a "transition layer" (or liquid-blob-like layer) is proposed. Here, the transition layer is to describe the interfacial region between the nucleus and aqueous solution, and this layer entails two functionalities: (1) it tends to retain CH4 depending on the degrees of supercooling and (2) it facilitates collision among CH4, which thus promote the incorporation of CH4 into nucleus. Our simulation indicates that compared to the near-rounded nucleus, the transition layer surrounding the elongated nucleus is more evident with the higher collision rate among CH4 molecules. As such, the transition layer tends to promote the elongated nucleus pathway, while offsetting the cost of larger surface free energy associated with the elongated nucleus. At 0.92 Tm, however, the transition layer gradually disappears, and classical nucleation events dominate. Overall, the notion of "transition layer" offers deeper insight into the NGH nucleation at different degrees of supercooling and could be extended to describe other types of hydrate nucleation.
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Affiliation(s)
- Liwen Li
- School of Petroleum Engineering and School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao, Shandong 266580, China
- Department of Materials Science & Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Xiao Wang
- School of Petroleum Engineering and School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao, Shandong 266580, China
| | - Youguo Yan
- School of Petroleum Engineering and School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao, Shandong 266580, China
| | - Joseph S Francisco
- Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6316, United States
| | - Jun Zhang
- School of Petroleum Engineering and School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao, Shandong 266580, China
| | - Xiao Cheng Zeng
- Department of Materials Science & Engineering, City University of Hong Kong, Hong Kong 999077, China
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Jie Zhong
- School of Petroleum Engineering and School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao, Shandong 266580, China
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7
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Zhang Y, Song Z, Lin Y, Shi Q, Hao Y, Fu Y, Wu J, Zhang Z. Predicting mechanical properties of CO 2hydrates: machine learning insights from molecular dynamics simulations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 36:015101. [PMID: 37714183 DOI: 10.1088/1361-648x/acfa55] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 09/15/2023] [Indexed: 09/17/2023]
Abstract
Understanding the mechanical properties of CO2hydrate is crucial for its diverse sustainable applications such as CO2geostorage and natural gas hydrate mining. In this work, classic molecular dynamics (MD) simulations are employed to explore the mechanical characteristics of CO2hydrate with varying occupancy rates and occupancy distributions of guest molecules. It is revealed that the mechanical properties, including maximum stress, critical strain, and Young's modulus, are not only affected by the cage occupancy rate in both large 51262and small 512cages, but also by the distribution of guest molecules within the cages. Specifically, the presence of vacancies in the 51262large cages significantly impacts the overall mechanical stability compared to 512small cages. Furthermore, four distinct machine learning (ML) models trained using MD results are developed to predict the mechanical properties of CO2hydrate with different cage occupancy rates and cage occupancy distributions. Through analyzing ML results, as-developed ML models highlight the importance of the distribution of guest molecules within the cages, as crucial contributor to the overall mechanical stability of CO2hydrate. This study contributes new knowledge to the field by providing insights into the mechanical properties of CO2hydrates and their dependence on cage occupancy rates and cage occupancy distributions. The findings have implications for the sustainable applications of CO2hydrate, and as-developed ML models offer a practical framework for predicting the mechanical properties of CO2hydrate in different scenarios.
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Affiliation(s)
- Yu Zhang
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, People's Republic of China
| | - Zixuan Song
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, People's Republic of China
| | - Yanwen Lin
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, People's Republic of China
| | - Qiao Shi
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, People's Republic of China
| | - Yongchao Hao
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, People's Republic of China
| | - Yuequn Fu
- PoreLab, The Njord Centre, Department of Physics, University of Oslo, Oslo 0588, Norway
| | - Jianyang Wu
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, People's Republic of China
- NTNU Nanomechanical Lab, Norwegian University of Science and Technology (NTNU), Trondheim 7491, Norway
| | - Zhisen Zhang
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Jiujiang Research Institute and Fujian Provincial Key Laboratory for Soft Functional Materials Research, Xiamen University, Xiamen 361005, People's Republic of China
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8
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Chaudhury A, Moorjani B, Chatterjee S, Adhikari J, Hait S. Molecular insights into the dissociation of carbon dioxide hydrates in the presence of an ionic liquid, [BMIM][PF6]. Chem Phys 2023; 571:111943. [DOI: 10.1016/j.chemphys.2023.111943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/19/2023]
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9
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Belosludov RV, Gets KV, Zhdanov RK, Bozhko YY, Belosludov VR, Chen LJ, Kawazoe Y. Molecular Dynamics Study of Clathrate-like Ordering of Water in Supersaturated Methane Solution at Low Pressure. Molecules 2023; 28:2960. [PMID: 37049727 PMCID: PMC10095827 DOI: 10.3390/molecules28072960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/23/2023] [Accepted: 03/24/2023] [Indexed: 03/29/2023] Open
Abstract
Using molecular dynamics, the evolution of a metastable solution for "methane + water" was studied for concentrations of 3.36, 6.5, 9.45, 12.2, and 14.8 mol% methane at 270 K and 1 bar during 100 ns. We have found the intriguing behavior of the system containing over 10,000 water molecules: the formation of hydrate-like structures is observed at 6.5 and 9.45 mol% concentrations throughout the entire solution volume. This formation of "blobs" and the following amorphous hydrate were studied. The creation of a metastable methane solution through supersaturation is the key to triggering the collective process of hydrate formation under low pressure. Even the first stage (0-1 ns), before the first fluctuating cavities appear, is a collective process of H-bond network reorganization. The formation of fluctuation cavities appears before steady hydrate growth begins and is associated with a preceding uniform increase in the water molecule's tetrahedrality. Later, the constantly presented hydrate cavities become the foundation for a few independent hydrate nucleation centers, this evolution is consistent with the labile cluster and local structure hypotheses. This new mechanism of hydrogen-bond network reorganization depends on the entropy of the cavity arrangement of the guest molecules in the hydrate lattice and leads to hydrate growth.
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Affiliation(s)
| | - Kirill V. Gets
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russia
- Department of Physics, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Ravil K. Zhdanov
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russia
- Department of Physics, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Yulia Y. Bozhko
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russia
- Department of Physics, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Vladimir R. Belosludov
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russia
- Department of Physics, Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Li-Jen Chen
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Yoshiyuki Kawazoe
- New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579, Japan
- Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankurathur 603203, India
- School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
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Abstract
Clathrate hydrates have diverse crystal structures, and among them, the three (sI, sII, and sH) most prevalent ones cover nearly all known structures, while the norm is to consider other structures only when specific guest molecules are present. Here we report the observation of a hidden clathrate structure: the tetragonal structure (TS-I) in commonly formed gas hydrates, as evidenced from molecular dynamics simulations. We show that when two (or more) sI crystal grains with different growth directions come into contact or when the growth of a sI crystal encounters geometrical frustration, the TS-I results as a cocrystal. We give evidence that TS-I may also play an important role in the combination and/or transition between sI and sII. These results imply that this previously neglected structure may be commonly present whenever sI or sII is formed. This hidden structure must be identified, experimentally and in simulations; confining the possible structures may hinder an in-depth understanding of clathrate hydrates.
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Affiliation(s)
- Yong Chen
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, P. R. China
- Phases to Flow Laboratory, Chemical & Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Satoshi Takeya
- National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - Amadeu K Sum
- Phases to Flow Laboratory, Chemical & Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, United States
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11
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Wang L, Hall K, Zhang Z, Kusalik PG. Mixed Hydrate Nucleation: Molecular Mechanisms and Cage Structures. J Phys Chem B 2022; 126:7015-7026. [PMID: 36047925 DOI: 10.1021/acs.jpcb.2c03223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The molecular-level details of the formation of mixed gas hydrates remain elusive despite their significance for a variety of scientific and industrial applications. In this study, extensive molecular simulations have been performed to examine the behavior of CH4/H2S mixed hydrate nucleation utilizing two different simulation setups varying in compositions and temperatures. The observed behavior exhibits similar phenomenology across the various systems once differences in nucleation rates and guest uptake are accounted for. We find that CH4 is always enriched in the hydrate phase while the aqueous phase is enriched in H2S. Even with H2S as a minor component (i.e., 10% mole fraction), the system can mirror the overall nucleation kinetics of pure H2S hydrate systems with CH4-dominant nuclei. Through analyses of cages and their transitions, nonstandard cages, particularly those with 12 faces (e.g., 51062), have been found to be key intermediate cage types in the early stage of nucleation. Additionally, we present previously unreported cage types comprising heptagonal faces (e.g., 596271) as having a significant role in the early-stage gas hydrate structural transitions.
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Affiliation(s)
- Lei Wang
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, T2N 1N4 Alberta, Canada
| | - Kyle Hall
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, T2N 1N4 Alberta, Canada
| | - Zhengcai Zhang
- Laboratory for Marine Mineral Resources, Pilot National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Peter G Kusalik
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, T2N 1N4 Alberta, Canada
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12
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Liu Y, Sun J, Chen C, Li W, Qin Y, Wang Y. Molecular insights into gas hydrate formation in the presence of graphene oxide solid surfaces. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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13
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Jing X, Luo Q, Cui X, Wang Q, Liu Y, Fu Z. Molecular Dynamics Simulation of CO2 Hydrate Growth in Salt Water. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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14
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Hu W, Chen C, Sun J, Zhang N, Zhao J, Liu Y, Ling Z, Li W, Liu W, Song Y. Three-body aggregation of guest molecules as a key step in methane hydrate nucleation and growth. Commun Chem 2022; 5:33. [PMID: 36697657 PMCID: PMC9814777 DOI: 10.1038/s42004-022-00652-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 02/16/2022] [Indexed: 02/01/2023] Open
Abstract
Gas hydrates have an important role in environmental and astrochemistry, as well as in energy materials research. Although it is widely accepted that gas accumulation is an important and necessary process during hydrate nucleation, how guest molecules aggregate remains largely unknown. Here, we have performed molecular dynamics simulations to clarify the nucleation path of methane hydrate. We demonstrated that methane gather with a three-body aggregate pattern corresponding to the free energy minimum of three-methane hydrophobic interaction. Methane molecules fluctuate around one methane which later becomes the central gas molecule, and when several methanes move into the region within 0.8 nm of the potential central methane, they act as directional methane molecules. Two neighbor directional methanes and the potential central methane form a three-body aggregate as a regular triangle with a distance of ~6.7 Å which is well within the range of typical methane-methane distances in hydrates or in solution. We further showed that hydrate nucleation and growth is inextricably linked to three-body aggregates. By forming one, two, and three three-body aggregates, the possibility of hydrate nucleation at the aggregate increases from 3/6, 5/6 to 6/6. The results show three-body aggregation of guest molecules is a key step in gas hydrate formation.
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Affiliation(s)
- Wenfeng Hu
- School of Energy and Power Engineering, Dalian University of Technology, 116024, Dalian, P. R. China
| | - Cong Chen
- School of Energy and Power Engineering, Dalian University of Technology, 116024, Dalian, P. R. China.
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, 116024, Dalian, P. R. China.
| | - Jingyue Sun
- School of Energy and Power Engineering, Dalian University of Technology, 116024, Dalian, P. R. China
| | - Ning Zhang
- School of Petroleum and Chemical Engineering, Dalian University of Technology, 124221, Panjin, P. R. China
| | - Jiafei Zhao
- School of Energy and Power Engineering, Dalian University of Technology, 116024, Dalian, P. R. China
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, 116024, Dalian, P. R. China
| | - Yu Liu
- School of Energy and Power Engineering, Dalian University of Technology, 116024, Dalian, P. R. China
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, 116024, Dalian, P. R. China
| | - Zheng Ling
- School of Energy and Power Engineering, Dalian University of Technology, 116024, Dalian, P. R. China
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, 116024, Dalian, P. R. China
| | - Weizhong Li
- School of Energy and Power Engineering, Dalian University of Technology, 116024, Dalian, P. R. China
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, 116024, Dalian, P. R. China
| | - Weiguo Liu
- School of Energy and Power Engineering, Dalian University of Technology, 116024, Dalian, P. R. China
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, 116024, Dalian, P. R. China
| | - Yongchen Song
- School of Energy and Power Engineering, Dalian University of Technology, 116024, Dalian, P. R. China.
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, 116024, Dalian, P. R. China.
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15
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A review of clathrate hydrate nucleation, growth and decomposition studied using molecular dynamics simulation. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118025] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Kainai D, Bai D. Effect of Cage Occupancy on Stability and Decomposition of Methane Hydrate. J Phys Chem B 2022; 126:492-502. [PMID: 34985263 DOI: 10.1021/acs.jpcb.1c07582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gas hydrates usually contain a certain number of empty cages that will both affect the hydrate stability and reduce the gas storage capacity. In this work, by MD simulations, we found that the hydrate stability is related to the cage occupancy, the empty cage types, and especially the distribution of empty cages. With the decrease of overall occupancy, the stability of hydrate becomes worse. Under the same overall occupancy, the more concentrated the empty cages are, the more unstable the hydrate is and hence the faster it decomposes. The methane molecules may migrate between distorted cages during the decomposition, resulting in a temporary increase in the stability of hydrate. Hydrates with different empty cage distributions show different decomposition mechanisms: when empty cages are concentrated, the melting rate is fast first due to the rapid decomposition of empty cages, but the remaining filled cages will reduce the melting rate; when empty cages are separated on the contrary, the early melting is slow because of the high local occupancy, and the following melting will be accelerated because of the high melting surface area. It indicates that the empty cage distribution plays a controlling role in hydrate decomposition kinetics at different stages.
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Affiliation(s)
- Dilare Kainai
- Department of Chemistry, College of Chemistry and Materials Engineering/Key Laboratory of Cosmetic, China National Light Industry, Beijing Technology and Business University, Beijing 100048, P. R. China
| | - Dongsheng Bai
- Department of Chemistry, College of Chemistry and Materials Engineering/Key Laboratory of Cosmetic, China National Light Industry, Beijing Technology and Business University, Beijing 100048, P. R. China
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17
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Lanza G, Chiacchio MA. On the size, shape and energetics of the hydration shell around alkanes. Phys Chem Chem Phys 2021; 23:24852-24865. [PMID: 34723301 DOI: 10.1039/d1cp02888j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A large number of clathrate-like cages have been proposed as the very first hydration shell of alkanes. The cages include canonical structures commonly found in clathrate hydrates and many others, not previously reported, derived from the carbon fullerene cavities. These structures have a rich and variegated form, which can adapt to the shape and conformation of the solute. They avoid "wasting" hydrogen bonds, while minimizing the volume cage and maximizing the solute-solvent van der Waals interactions. DFT/M06-2X and MP2 ab initio calculations give comparable structural and energetic results although the latter predicts slightly larger cages for a given solute. It is shown that the van der Waals interactions are substantial and the large exoenergetic values found for isobutane and cyclopentane provide an explanation for the surprising high melting points of related hydrates at room pressure. The encaging enthalpy for various hydrocarbons is similar to the enthalpy of solution measured at a temperature just above the melting point of aqueous hydrocarbon solutions, thus indicating that water molecules should not deviate too much from the configuration with O-H bonds tangentially oriented with respect to the solute surface. The computed trend differs from the enthalpy of solution measured at room temperature, thus the very first hydration shell departs, up to a certain degree, from the clathrate-like structures.
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Affiliation(s)
- Giuseppe Lanza
- A Dipartimento di Scienze del Farmaco e della Salute, Università di Catania, Viale A. Doria 6, Catania, Italy.
| | - Maria Assunta Chiacchio
- A Dipartimento di Scienze del Farmaco e della Salute, Università di Catania, Viale A. Doria 6, Catania, Italy.
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18
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Abstract
Water and methane can stay together under low temperature and high pressure in the forms of liquid solutions and crystalline solids. From liquid and gaseous states to crystalline solids or the contrary processes, amorphous methane hydrates can occur in these evolution scenarios. Herein, mechanical properties of amorphous methane hydrates are explored for the first time to bridge the gap between mechanical responses of monocrystalline and polycrystalline methane hydrates. Our results demonstrate that mechanical properties of amorphous methane hydrates are strongly governed by our original proposed order parameter, namely, normalized hydrogen-bond directional order parameter. Followed by this important achievement, a multistep deformation mechanism core is proposed to explain mechanical properties of amorphous methane hydrates. Through an extensive detailed analysis of amorphous methane hydrates, our simulation results not only greatly enlarge our fundamental understanding for mechanical responses of amorphous methane hydrates in geological systems but also offer a fresh perspective in structure-property topics of solid materials in future science and technology.
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Affiliation(s)
- Pinqiang Cao
- School of Resource and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China
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19
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20
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Liu N, Liu T. Different pathways for methane hydrate nucleation and crystallization at high supercooling: Insights from molecular dynamics simulations. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115466] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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21
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Gilmore RAJ, Misquitta AJ, Dove MT. Methane hydrate clathrates: effects in the simulation of melting arising from the assumption of simple combining rules in interatomic potentials. MOLECULAR SIMULATION 2021. [DOI: 10.1080/08927022.2019.1572139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- R. A. J. Gilmore
- School of Physics and Astronomy, Queen Mary University of London, London UK
| | - A. J. Misquitta
- School of Physics and Astronomy, Queen Mary University of London, London UK
| | - M. T. Dove
- School of Physics and Astronomy, Queen Mary University of London, London UK
- Department of Physics, School of Sciences, Wuhan University of Technology, Wuhan, People's Republic of China
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22
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Hao Y, Xu Z, Du S, Yang X, Ding T, Wang B, Xu J, Zhang J, Yin H. Iterative Cup Overlapping: An Efficient Identification Algorithm for Cage Structures of Amorphous Phase Hydrates. J Phys Chem B 2021; 125:1282-1292. [PMID: 33481597 DOI: 10.1021/acs.jpcb.0c08964] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Molecular dynamics studies have revealed that the nucleation pathway of clathrate hydrates involves the evolution from amorphous to crystalline hydrates. In this study, complete cages are further classified into the standard edge-saturated cages (SECs) and nonstandard edge-saturated cages (non-SECs). Centered on studying the structure and evolution of non-SECs and SECs, we propose a novel and efficient algorithm, iterative cup overlapping (ICO), to monitor hydrate nucleation and growth in molecular simulations by identifying SECs and discuss possible causes of the instability of non-SECs. Manipulation of topological information makes it possible for ICO to avoid the repeated searches for identified cages and deduce all SECs with low time costs, improving the efficiency of identification significantly. The accuracy and efficiency of ICO were verified by comparing the identification results with other well-proven algorithms. Furthermore, it was found that non-SECs have short lifetimes and eventually decompose or reorganize into more stable structures. Some evidence suggests that the instability of non-SECs is closely related to the hydrogen-bonding configuration of water-ring aggregations that they contain. The spontaneous evolution of the hydrogen-bonding network into the tetrahedral network may be the main factor that causes the conversion of QWRAs and the evolution of non-SECs.
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Affiliation(s)
- Yongchao Hao
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China
| | - Zhe Xu
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China
| | - Shuai Du
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China
| | - Xuefeng Yang
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China
| | - Tingji Ding
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China
| | - Bowen Wang
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China
| | - Jiafang Xu
- School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China.,Key Laboratory of Unconventional Oil & Gas Development (China University of Petroleum (East China)), Ministry of Education, Qingdao 266580, P. R. China
| | - Jun Zhang
- School of Material Science & Engineering, China University of Petroleum (East China), Qingdao 266580, P. R. China
| | - Haiqing Yin
- School of Science, China University of Petroleum (East China), Qingdao 266580, P. R. China
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23
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Li L, Zhong J, Yan Y, Zhang J, Xu J, Francisco JS, Zeng XC. Unraveling nucleation pathway in methane clathrate formation. Proc Natl Acad Sci U S A 2020; 117:24701-24708. [PMID: 32958648 PMCID: PMC7547213 DOI: 10.1073/pnas.2011755117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Methane clathrates are widespread on the ocean floor of the Earth. A better understanding of methane clathrate formation has important implications for natural-gas exploitation, storage, and transportation. A key step toward understanding clathrate formation is hydrate nucleation, which has been suggested to involve multiple evolution pathways. Herein, a unique nucleation/growth pathway for methane clathrate formation has been identified by analyzing the trajectories of large-scale molecular dynamics (MD) simulations. In particular, ternary water-ring aggregations (TWRAs) have been identified as fundamental structures for characterizing the nucleation pathway. Based on this nucleation pathway, the critical nucleus size and nucleation timescale can be quantitatively determined. Specifically, a methane hydration layer compression/shedding process is observed to be the critical step in (and driving) the nucleation/growth pathway, which is manifested through overlapping/compression of the surrounding hydration layers of the methane molecules, followed by detachment (shedding) of the hydration layer. As such, an effective way to control methane hydrate nucleation is to alter the hydration layer compression/shedding process during the course of nucleation.
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Affiliation(s)
- Liwen Li
- School of Materials Science and Engineering, China University of Petroleum (East China), 266580 Qingdao, China
| | - Jie Zhong
- Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104-6316
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6316
| | - Youguo Yan
- School of Materials Science and Engineering, China University of Petroleum (East China), 266580 Qingdao, China
| | - Jun Zhang
- School of Materials Science and Engineering, China University of Petroleum (East China), 266580 Qingdao, China;
| | - Jiafang Xu
- School of Petroleum Engineering, China University of Petroleum (East China), 266580 Qingdao, China;
- Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum (East China), Ministry of Education, 266580 Qingdao, China
| | - Joseph S Francisco
- Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104-6316;
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6316
| | - Xiao Cheng Zeng
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588;
- Department of Chemical & Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588
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24
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Chen Y, Chen C, Sum AK. Propane and Water: The Cooperativity of Unlikely Molecules to Form Clathrate Structures. J Phys Chem B 2020; 124:4661-4671. [PMID: 32395996 DOI: 10.1021/acs.jpcb.0c02675] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Many unanswered questions still exist at the molecular level to understand the nucleation process and mechanism of clathrate hydrates, especially for larger guest molecules that would result in the structure II crystal. Here, we report on molecular dynamics simulations for propane and water to describe the molecular mechanism leading to a structure II system. Through a large number (30) of long (5 μs) and coupled annealing (20 μs) simulations, we detail the prenucleation, nucleation, growth, and annealing of propane clathrate hydrate structures at 250 K and 1800 bar. The results demonstrate the equal importance of the empty and occupied cages in the nucleation of propane hydrates. The critical nucleus size is identified to be eight cages. While separate distinct clusters may exist during the prenucleation period, only one survives to grow beyond the critical nucleus size, with the others remaining subcritical. From the annealing simulations, it is clear that solid rearrangement is a very slow process, and 20 μs is still not long enough to capture long-range ordering resembling the structure II crystal. These results, along with the developed analysis method, have a significant impact in advancing our understanding of the nucleation process for unlike molecules.
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Affiliation(s)
- Yong Chen
- Construction Engineering College, Jilin University, Changchun, Jilin Province 130026, P. R. China.,Phases to Flow Laboratory, Chemical & Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Chen Chen
- Construction Engineering College, Jilin University, Changchun, Jilin Province 130026, P. R. China
| | - Amadeu K Sum
- Phases to Flow Laboratory, Chemical & Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, United States
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25
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Yu KB, Yazaydin AO. Does Confinement Enable Methane Hydrate Growth at Low Pressures? Insights from Molecular Dynamics Simulations. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2020; 124:11015-11022. [PMID: 32582402 PMCID: PMC7304911 DOI: 10.1021/acs.jpcc.0c02246] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/30/2020] [Indexed: 05/23/2023]
Abstract
Natural methane hydrates are estimated to be the largest source of unexploited hydrocarbon fuel. The ideal conditions for methane hydrate formation are low temperatures and high pressures. On the other hand, recent experimental studies suggest that porous materials, thanks to their confinement effects, can enable methane hydrate formation at milder conditions, although there has not been a consensus on this. A number of studies have investigated methane hydrate growth in confinement by employing molecular simulations; however, these were carried out at either very high pressures or very low temperatures. Therefore, the effects of confinement on methane hydrate growth at milder conditions have not yet been elaborated by molecular simulations. In order to address this, we carried out a systematic study by performing molecular dynamics (MD) simulations of methane water systems. Using a direct phase coexistence approach, microsecond-scale MD simulations in the isobaric-isothermal (NPT) ensemble were performed in order to study the behavior of methane hydrates in the bulk and in confined nanospaces of hydroxylated silica pores at external pressures ranging from 1 to 100 bar and a simulation temperature corresponding to a 2 °C experimental temperature. We validated the combination of the TIP4P/ice water and TraPPE-UA methane models in order to correctly predict the behavior of methane hydrates in accordance to their phase equilibria. We also demonstrated that the dispersion corrections applied to short-range interactions lead to artificially induced hydrate growth. We observed that in the confinement of a hydroxylated silica pore, a convex-shaped methane nanobuble forms, and methane hydrate growth primarily takes place in the center of the pore rather than the surfaces where a thin water layer exists. Most importantly, our study showed that in the nanopores methane hydrate growth can indeed take place at pressures which would be too low for the growth of methane hydrates in the bulk.
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26
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Zheng J, Yang L, Ma S, Zhao Y, Yang M. Quantitative analysis of CO
2
hydrate formation in porous media by proton NMR. AIChE J 2019. [DOI: 10.1002/aic.16820] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Jia‐nan Zheng
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian China
| | - Lei Yang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian China
| | - Shihui Ma
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian China
| | - Yuechao Zhao
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian China
| | - Mingjun Yang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian China
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27
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Yi L, Zhou X, He Y, Cai Z, Zhao L, Zhang W, Shao Y. Molecular Dynamics Simulation Study on the Growth of Structure II Nitrogen Hydrate. J Phys Chem B 2019; 123:9180-9186. [PMID: 31609605 DOI: 10.1021/acs.jpcb.9b06386] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Crystal growth of N2 hydrate in a three-phase system consisting of N2 hydrate, liquid water, and gaseous N2 was performed by molecular dynamics simulation at 260 K. Pressure influence on hydrate growth was evaluated. The kinetic properties including the growth rates and cage occupancies of the newly formed hydrate and the diffusion coefficient and concentration of N2 molecules in liquid phase were measured. The results showed that the growth of N2 hydrate could be divided into two stages where N2 molecules in gas phase had to dissolve in liquid phase and then form hydrate cages at the liquid-hydrate interface. The diffusion coefficient and concentration of N2 in liquid phase increased linearly with increasing pressure. As the pressure rose from 50 to 100 MPa, the hydrate growth rate kept increasing from 0.11 to 0.62 cages·ns-1·Å-2 and then dropped down to around 0.40 cages·ns-1·Å-2 once the pressure surpassed 100 MPa. During the hydrate formation, the initial sII N2 hydrate phase set in the system served as a template for the subsequent growth of N2 hydrate so that no new crystal structure was found. Analysis on the cage occupancies revealed that the amount of cages occupied by two N2 molecules increased evidently when the pressure was above 100 MPa, which slowed down the growth rate of hydrate cages. Additionally, a small fraction of defective cages including two N2 molecules trapped in 51265 cages and three N2 molecules trapped 51268 cages was observed during the hydrate growth.
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Affiliation(s)
| | - Xuebing Zhou
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences , Guangzhou 510640 , China
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28
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Factorovich MH, Naullage PM, Molinero V. Can clathrates heterogeneously nucleate ice? J Chem Phys 2019; 151:114707. [DOI: 10.1063/1.5119823] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Matías H. Factorovich
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, USA
| | - Pavithra M. Naullage
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, USA
| | - Valeria Molinero
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, USA
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29
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Nakate P, Ghosh B, Das S, Roy S, Kumar R. Molecular dynamics study on growth of carbon dioxide and methane hydrate from a seed crystal. Chin J Chem Eng 2019. [DOI: 10.1016/j.cjche.2019.02.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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30
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Striolo A, Phan A, Walsh MR. Molecular properties of interfaces relevant for clathrate hydrate agglomeration. Curr Opin Chem Eng 2019. [DOI: 10.1016/j.coche.2019.08.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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Liang S, Hall KW, Laaksonen A, Zhang Z, Kusalik PG. Characterizing key features in the formation of ice and gas hydrate systems. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2019; 377:20180167. [PMID: 30982452 PMCID: PMC6501917 DOI: 10.1098/rsta.2018.0167] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/26/2019] [Indexed: 05/16/2023]
Abstract
Crystallization in liquids is critical to a range of important processes occurring in physics, chemistry and life sciences. In this article, we review our efforts towards understanding the crystallization mechanisms, where we focus on theoretical modelling and molecular simulations applied to ice and gas hydrate systems. We discuss the order parameters used to characterize molecular ordering processes and how different order parameters offer different perspectives of the underlying mechanisms of crystallization. With extensive simulations of water and gas hydrate systems, we have revealed unexpected defective structures and demonstrated their important roles in crystallization processes. Nucleation of gas hydrates can in most cases be characterized to take place in a two-step mechanism where the nucleation occurs via intermediate metastable precursors, which gradually reorganizes to a stable crystalline phase. We have examined the potential energy landscapes explored by systems during nucleation, and have shown that these landscapes are rugged and funnel-shaped. These insights provide a new framework for understanding nucleation phenomena that has not been addressed in classical nucleation theory. This article is part of the theme issue 'The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets'.
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Affiliation(s)
- Shuai Liang
- Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangdong Key Laboratory of New and Renewable Energy Research and Development, Guangzhou, People's Republic of China
| | - Kyle Wm. Hall
- Department of Chemistry, Temple University, Philadelphia, PA, USA
| | - Aatto Laaksonen
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden
- Department of Chemistry-Ångström Laboratory, Uppsala University, 75121 Uppsala, Sweden
- Centre of Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry, Aleea Grigore Ghica-Voda, 41A, 700487 Iasi, Romania
| | - Zhengcai Zhang
- Department of Chemistry, University of Calgary, Calgary, Canada
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32
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Li K, Shi R, Tang L, Huang Y, Cao X, Su Y. Cage fusion from bi-cages to tri-cages during nucleation of methane hydrate: a DFT-D simulation. Phys Chem Chem Phys 2019; 21:9150-9158. [PMID: 30675605 DOI: 10.1039/c8cp07207h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Water-cage clusters encapsulating guest molecules are the basic components of hydrate crystal structures. Herein, we investigated the fusion process from bi-cages to tri-cages to probe the nucleation mechanism at the initial stage of CH4 hydrate formation by employing dispersion-corrected density functional theory. We found that tri-cages possess high stability by sharing three, rather than two, polygonal faces. In addition, any mono-cage combined with a nonstandard 4151062 cage could achieve considerable stability regardless of which face is shared; this finding illustrates that 4151062 cages are more likely to appear at the early stages of CH4 hydrate nucleation than other nonstandard cages. We then simulated the Raman spectra of CH4 molecules in water-cage to characterize the spectral characteristics of the CH4 hydrate. The C-H symmetric stretching frequency of encapsulated CH4 molecules red-shifted with increasing mono-cage size, which follows the prediction of the "loose cage-tight cage" model. The symmetric stretching vibrational frequencies of trapped CH4 molecules in the tri-cage revealed a clear red-shift compared with those in the component mono- and bi-cages. The cage fusion process and spectroscopic properties described in this work are expected to provide new atomistic insights into CH4 hydrates at the initial nucleation stage.
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Affiliation(s)
- Keyao Li
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024, China.
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33
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Veesam SK, Ravipati S, Punnathanam SN. Recent advances in thermodynamics and nucleation of gas hydrates using molecular modeling. Curr Opin Chem Eng 2019. [DOI: 10.1016/j.coche.2019.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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34
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Abdulsalam J, Mulopo J, Amosa MK, Bada S, Falcon R, Oboirien BO. Towards a cleaner natural gas production: recent developments on purification technologies. SEP SCI TECHNOL 2018. [DOI: 10.1080/01496395.2018.1547761] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Jibril Abdulsalam
- Sustainable Energy and Environment Research Group, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, South Africa
- Clean Coal and Sustainable Energy Research Group, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa
| | - Jean Mulopo
- Sustainable Energy and Environment Research Group, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, South Africa
| | - Mutiu K. Amosa
- NRF-DST Sustainable Process Engineering, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, South Africa
- Environmental Engineering and Management Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam
- Faculty of Environment and Labour Safety, Ton Duc Thang University, Ho Chi Minh City, Vietnam
| | - Samson Bada
- Clean Coal and Sustainable Energy Research Group, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa
| | - Rosemary Falcon
- Clean Coal and Sustainable Energy Research Group, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa
| | - Bilainu O. Oboirien
- Department of Chemical Engineering, University of Johannesburg, Doornfontein Johannesburg, South Africa
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35
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Hou J, Bai D, Zhou W. Methane Hydrate Nucleation within Elastic Confined Spaces: Suitable Spacing and Elasticity Can Accelerate the Nucleation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:10889-10896. [PMID: 30157653 DOI: 10.1021/acs.langmuir.8b02387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Elastic materials are candidates for process intensification of gas storage by forming gas hydrate. In this work, molecular dynamics simulations of hydrate nucleation in elastic silica double layers were performed to study the effect of elastic confined spaces on hydrate formation. It is found that in narrow confined spaces, hexagonal rings dominated the hydrogen bond network of water molecules established rapidly by a multisite nucleation mechanism. With molecules added, a bilayer water structure was formed finally because elastic space can adapt the volume expansion. In medium and wide confined spaces, hydrates were formed from a series of "pseudo cages" which are considered as precursors of complete hydrate cages. Moreover, the induction time for nucleation was a minimum when the elasticity of the silica layer changes: nucleation is fastest in the weak-elastic system. When the elasticity increases, it becomes hard to adapt the volume expansion during nucleation and also difficult to nucleate in very weak-elastic systems because of the fluctuation of the layers.
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Affiliation(s)
- Jingpeng Hou
- Department of Chemistry, School of Science/Key Laboratory of Cosmetic, China National Light Industry , Beijing Technology and Business University , Beijing 100048 , PR China
| | - Dongsheng Bai
- Department of Chemistry, School of Science/Key Laboratory of Cosmetic, China National Light Industry , Beijing Technology and Business University , Beijing 100048 , PR China
| | - Wei Zhou
- Department of Chemistry, School of Science/Key Laboratory of Cosmetic, China National Light Industry , Beijing Technology and Business University , Beijing 100048 , PR China
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36
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Jiménez-Ángeles F, Firoozabadi A. Hydrophobic Hydration and the Effect of NaCl Salt in the Adsorption of Hydrocarbons and Surfactants on Clathrate Hydrates. ACS CENTRAL SCIENCE 2018; 4:820-831. [PMID: 30062110 PMCID: PMC6062839 DOI: 10.1021/acscentsci.8b00076] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Indexed: 05/16/2023]
Abstract
Adsorption of functional molecules on the surface of hydrates is key in the understanding of hydrate inhibitors. We investigate the adsorption of a hydrocarbon chain, nonionic and ionic surfactants, and ions at the hydrate-aqueous interface. Our results suggest a strong connection between the water ordering around solutes in bulk and the affinity for the hydrates surface. We distinguish two types of water ordering around solutes: (i) hydrophobic hydration where water molecules form a hydrogen bond network similar to clathrate hydrates, and (ii) ionic hydration where water molecules align according to the polarity of an ionic group. The nonionic surfactant and the hydrocarbon chain induce hydrophobic hydration and are favorably adsorbed on the hydrate surface. Adsorption of ions and the ionic headgroups on the hydrate surface is not favorable because ionic hydration and the hydrogen bond structure of hydrates are incompatible. The nonionic surfactant is adsorbed by the headgroup and tail while adsorption of the ionic surfactants is not favorable through the head. Water ordering is analyzed using the hydrogen bond and tetrahedral density profiles as a function of the distance to the chemical groups. The adsorption of solutes is studied through the free energy profiles as a function of the distance to the hydrate surface. Salt lowers the melting temperature of hydrates, disrupts hydrophobic hydration, reduces the solubility of solutes in the aqueous solution, and increases the propensity of solutes to be adsorbed on hydrate surfaces. Our studies are performed by the unbiased and steered molecular dynamics simulations. The results are in line with experiments on the effect of salt and alkanes in hydrate antiagglomeration.
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Affiliation(s)
| | - Abbas Firoozabadi
- Reservoir
Engineering Research Institute, Palo Alto, California 94301, United States
- Department
of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06510, United States
- E-mail: . Phone: +1 (650) 326-9172. Fax: +1 (650) 472-9285
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37
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Bi Y, Porras A, Li T. Free energy landscape and molecular pathways of gas hydrate nucleation. J Chem Phys 2018; 145:211909. [PMID: 28799352 DOI: 10.1063/1.4961241] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Despite the significance of gas hydrates in diverse areas, a quantitative knowledge of hydrate formation at a molecular level is missing. The impediment to acquiring this understanding is primarily attributed to the stochastic nature and ultra-fine scales of nucleation events, posing a great challenge for both experiment and simulation to explore hydrate nucleation. Here we employ advanced molecular simulation methods, including forward flux sampling (FFS), pB histogram analysis, and backward flux sampling, to overcome the limit of direct molecular simulation for exploring both the free energy landscape and molecular pathways of hydrate nucleation. First we test the half-cage order parameter (H-COP) which we developed for driving FFS, through conducting the pB histogram analysis. Our results indeed show that H-COP describes well the reaction coordinates of hydrate nucleation. Through the verified order parameter, we then directly compute the free energy landscape for hydrate nucleation by combining both forward and backward flux sampling. The calculated stationary distribution density, which is obtained independently of nucleation theory, is found to fit well against the classical nucleation theory (CNT). Subsequent analysis of the obtained large ensemble of hydrate nucleation trajectories show that although on average, hydrate formation is facilitated by a two-step like mechanism involving a gradual transition from an amorphous to a crystalline structure, there also exist nucleation pathways where hydrate crystallizes directly, without going through the amorphous stage. The CNT-like free energy profile and the structural diversity suggest the existence of multiple active transition pathways for hydrate nucleation, and possibly also imply the near degeneracy in their free energy profiles among different pathways. Our results thus bring a new perspective to the long standing question of how hydrates crystallize.
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Affiliation(s)
- Yuanfei Bi
- Department of Civil and Environmental Engineering, George Washington University, Washington DC 20052, USA
| | - Anna Porras
- Department of Civil and Environmental Engineering, George Washington University, Washington DC 20052, USA
| | - Tianshu Li
- Department of Civil and Environmental Engineering, George Washington University, Washington DC 20052, USA
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38
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Warrier P, Khan MN, Srivastava V, Maupin CM, Koh CA. Overview: Nucleation of clathrate hydrates. J Chem Phys 2018; 145:211705. [PMID: 28799342 DOI: 10.1063/1.4968590] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular level knowledge of nucleation and growth of clathrate hydrates is of importance for advancing fundamental understanding on the nature of water and hydrophobic hydrate formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when hydrate structures nucleate will be tremendously beneficial for the development of sustainable hydrate management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of hydrate nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to hydrates. Hydrate nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various hydrate nucleation hypotheses and hydrate nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on hydrate nucleation are discussed in detail followed by potential future research directions.
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Affiliation(s)
- Pramod Warrier
- Center for Hydrate Research, Chemical and Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, USA
| | - M Naveed Khan
- Center for Hydrate Research, Chemical and Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, USA
| | - Vishal Srivastava
- Center for Hydrate Research, Chemical and Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, USA
| | - C Mark Maupin
- Center for Hydrate Research, Chemical and Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, USA
| | - Carolyn A Koh
- Center for Hydrate Research, Chemical and Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401, USA
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39
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Different Mechanism Effect between Gas-Solid and Liquid-Solid Interface on the Three-Phase Coexistence Hydrate System Dissociation in Seawater: A Molecular Dynamics Simulation Study. ENERGIES 2017. [DOI: 10.3390/en11010006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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40
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He Z, Linga P, Jiang J. CH 4 Hydrate Formation between Silica and Graphite Surfaces: Insights from Microsecond Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:11956-11967. [PMID: 28991480 DOI: 10.1021/acs.langmuir.7b02711] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Microsecond simulations have been performed to investigate CH4 hydrate formation from gas/water two-phase systems between silica and graphite surfaces, respectively. The hydrophilic silica and hydrophobic graphite surfaces exhibit substantially different effects on CH4 hydrate formation. The graphite surface adsorbs CH4 molecules to form a nanobubble with a flat or negative curvature, resulting in a low aqueous CH4 concentration, and hydrate nucleation does not occur during 2.5 μs simulation. Moreover, an ordered interfacial water bilayer forms between the nanobubble and graphite surface thus preventing their direct contact. In contrast, the hydroxylated-silica surface prefers to be hydrated by water, with a cylindrical nanobubble formed in the solution, leading to a high aqueous CH4 concentration and hydrate nucleation in the bulk region; during hydrate growth, the nanobubble is gradually covered by hydrate solid and separated from the water phase, hence slowing growth. The silanol groups on the silica surface can form strong hydrogen bonds with water, and hydrate cages need to match the arrangements of silanols to form more hydrogen bonds. At the end of the simulation, the hydrate solid is separated from the silica surface by liquid water, with only several cages forming hydrogen bonds with the silica surface, mainly due to the low CH4 aqueous concentrations near the surface. To further explore hydrate formation between graphite surfaces, CH4/water homogeneous solution systems are also simulated. CH4 molecules in the solution are adsorbed onto graphite and hydrate nucleation occurs in the bulk region. During hydrate growth, the adsorbed CH4 molecules are gradually converted into hydrate solid. It is found that the hydrate-like ordering of interfacial water induced by graphite promotes the contact between hydrate solid and graphite. We reveal that the ability of silanol groups on silica to form strong hydrogen bonds to stabilize incipient hydrate solid, as well as the ability of graphite to adsorb CH4 molecules and induce hydrate-like ordering of the interfacial water, are the key factors to affect CH4 hydrate formation between silica and graphite surfaces.
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Affiliation(s)
- Zhongjin He
- Department of Chemical and Biomolecular Engineering, National University of Singapore , Singapore 117576, Singapore
| | - Praveen Linga
- Department of Chemical and Biomolecular Engineering, National University of Singapore , Singapore 117576, Singapore
| | - Jianwen Jiang
- Department of Chemical and Biomolecular Engineering, National University of Singapore , Singapore 117576, Singapore
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41
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Zhang Z, Guo GJ. The effects of ice on methane hydrate nucleation: a microcanonical molecular dynamics study. Phys Chem Chem Phys 2017; 19:19496-19505. [DOI: 10.1039/c7cp03649c] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The NVE simulations realize the ice shrinking when methane hydrate nucleates both heterogeneously and homogeneously.
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Affiliation(s)
- Zhengcai Zhang
- Key Laboratory of Earth and Planetary Physics
- Institute of Geology and Geophysics
- Chinese Academy of Sciences
- Beijing 100029
- China
| | - Guang-Jun Guo
- Key Laboratory of Earth and Planetary Physics
- Institute of Geology and Geophysics
- Chinese Academy of Sciences
- Beijing 100029
- China
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42
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Sujith KS, Ramachandran CN. Natural Gas Evolution in a Gas Hydrate Melt: Effect of Thermodynamic Hydrate Inhibitors. J Phys Chem B 2016; 121:153-163. [DOI: 10.1021/acs.jpcb.6b07782] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- K. S. Sujith
- Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - C. N. Ramachandran
- Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India
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43
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Hall KW, Zhang Z, Kusalik PG. Unraveling Mixed Hydrate Formation: Microscopic Insights into Early Stage Behavior. J Phys Chem B 2016; 120:13218-13223. [PMID: 27990805 DOI: 10.1021/acs.jpcb.6b11961] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The molecular-level details of mixed hydrate nucleation remain unclear despite the broad implications of this process for a variety of scientific domains. Through analysis of mixed hydrate nucleation in a prototypical CH4/H2S/H2O system, we demonstrate that high-level kinetic similarities between mixed hydrate systems and corresponding pure hydrate systems are not a reliable basis for estimating the composition of early stage mixed hydrate nuclei. Moreover, we show that solution compositions prior to and during nucleation are not necessarily effective proxies for the composition of early stage mixed hydrate nuclei. Rather, microscopic details, (e.g., guest-host interactions and previously neglected cage types) apparently play key roles in determining early stage behavior of mixed hydrates. This work thus provides key foundational concepts and insights for understanding mixed hydrate nucleation.
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Affiliation(s)
- Kyle Wm Hall
- Department of Chemistry, University of Calgary , 2500 University Drive NW, Calgary, T2N 1N4 Alberta, Canada
| | - Zhengcai Zhang
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences , Beijing 100029, China
| | - Peter G Kusalik
- Department of Chemistry, University of Calgary , 2500 University Drive NW, Calgary, T2N 1N4 Alberta, Canada
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44
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Hall KW, Carpendale S, Kusalik PG. Evidence from mixed hydrate nucleation for a funnel model of crystallization. Proc Natl Acad Sci U S A 2016; 113:12041-12046. [PMID: 27790987 PMCID: PMC5087014 DOI: 10.1073/pnas.1610437113] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The molecular-level details of crystallization remain unclear for many systems. Previous work has speculated on the phenomenological similarities between molecular crystallization and protein folding. Here we demonstrate that molecular crystallization can involve funnel-shaped potential energy landscapes through a detailed analysis of mixed gas hydrate nucleation, a prototypical multicomponent crystallization process. Through this, we contribute both: (i) a powerful conceptual framework for exploring and rationalizing molecular crystallization, and (ii) an explanation of phenomenological similarities between protein folding and crystallization. Such funnel-shaped potential energy landscapes may be typical of broad classes of molecular ordering processes, and can provide a new perspective for both studying and understanding these processes.
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Affiliation(s)
- Kyle Wm Hall
- Department of Chemistry, University of Calgary, Calgary, AB, Canada T2N 1N4
| | - Sheelagh Carpendale
- Department of Computer Science, University of Calgary, Calgary, AB, Canada T2N 1N4
| | - Peter G Kusalik
- Department of Chemistry, University of Calgary, Calgary, AB, Canada T2N 1N4;
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45
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Yan KF, Li XS, Chen ZY, Xia ZM, Xu CG, Zhang Z. Molecular Dynamics Simulation of the Crystal Nucleation and Growth Behavior of Methane Hydrate in the Presence of the Surface and Nanopores of Porous Sediment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:7975-7984. [PMID: 27398713 DOI: 10.1021/acs.langmuir.6b01601] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The behavior of hydrate formation in porous sediment has been widely studied because of its importance in the investigation of reservoirs and in the drilling of natural gas hydrate. However, it is difficult to understand the hydrate nucleation and growth mechanism on the surface and in the nanopores of porous media by experimental and numerical simulation methods. In this work, molecular dynamics simulations of the nucleation and growth of CH4 hydrate in the presence of the surface and nanopores of clay are carried out. The molecular configurations and microstructure properties are analyzed for systems containing one H2O hydrate layer (System A), three H2O hydrate layers (System B), and six H2O hydrate layers (System C) in both clay and the bulk solution. It is found that hydrate formation is more complex in porous media than in the pure bulk solution and that there is cooperativity between hydrate growth and molecular diffusion in clay nanopores. The hydroxylated edge sites of the clay surface could serve as a source of CH4 molecules to facilitate hydrate nucleation. The diffusion velocity of molecules is influenced by the growth of the hydrate that forms a block in the throats of the clay nanopore. Comparing hydrate growth in different clay pore sizes reveals that the pore size plays an important role in hydrate growth and molecular diffusion in clay. This simulation study provides the microscopic mechanism of hydrate nucleation and growth in porous media, which can be favorable for the investigation of the formation of natural gas hydrate in sediments.
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Affiliation(s)
- Ke-Feng Yan
- Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences , Guangzhou 510640, China
- Guangdong Key Laboratory of New and Renewable Energy Research and Development , Guangzhou 510640, China
| | - Xiao-Sen Li
- Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences , Guangzhou 510640, China
- Guangdong Key Laboratory of New and Renewable Energy Research and Development , Guangzhou 510640, China
| | - Zhao-Yang Chen
- Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences , Guangzhou 510640, China
- Guangdong Key Laboratory of New and Renewable Energy Research and Development , Guangzhou 510640, China
| | - Zhi-Ming Xia
- Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences , Guangzhou 510640, China
- Guangdong Key Laboratory of New and Renewable Energy Research and Development , Guangzhou 510640, China
| | - Chun-Gang Xu
- Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences , Guangzhou 510640, China
- Guangdong Key Laboratory of New and Renewable Energy Research and Development , Guangzhou 510640, China
| | - Zhiqiang Zhang
- College of Mining Engineering, Taiyuan University of Technology , Taiyuan 030024, China
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46
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Zhang Z, Liu CJ, Walsh MR, Guo GJ. Effects of ensembles on methane hydrate nucleation kinetics. Phys Chem Chem Phys 2016; 18:15602-8. [PMID: 27222203 DOI: 10.1039/c6cp02171a] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
By performing molecular dynamics simulations to form a hydrate with a methane nano-bubble in liquid water at 250 K and 50 MPa, we report how different ensembles, such as the NPT, NVT, and NVE ensembles, affect the nucleation kinetics of the methane hydrate. The nucleation trajectories are monitored using the face-saturated incomplete cage analysis (FSICA) and the mutually coordinated guest (MCG) order parameter (OP). The nucleation rate and the critical nucleus are obtained using the mean first-passage time (MFPT) method based on the FS cages and the MCG-1 OPs, respectively. The fitting results of MFPT show that hydrate nucleation and growth are coupled together, consistent with the cage adsorption hypothesis which emphasizes that the cage adsorption of methane is a mechanism for both hydrate nucleation and growth. For the three different ensembles, the hydrate nucleation rate is quantitatively ordered as follows: NPT > NVT > NVE, while the sequence of hydrate crystallinity is exactly reversed. However, the largest size of the critical nucleus appears in the NVT ensemble, rather than in the NVE ensemble. These results are helpful for choosing a suitable ensemble when to study hydrate formation via computer simulations, and emphasize the importance of the order degree of the critical nucleus.
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Affiliation(s)
- Zhengcai Zhang
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
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47
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A Theoretical Study of the Hydration of Methane, from the Aqueous Solution to the sI Hydrate-Liquid Water-Gas Coexistence. Int J Mol Sci 2016; 17:ijms17060378. [PMID: 27240339 PMCID: PMC4926321 DOI: 10.3390/ijms17060378] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 02/24/2016] [Accepted: 02/26/2016] [Indexed: 11/30/2022] Open
Abstract
Monte Carlo and molecular dynamics simulations were done with three recent water models TIP4P/2005 (Transferable Intermolecular Potential with 4 Points/2005), TIP4P/Ice (Transferable Intermolecular Potential with 4 Points/ Ice) and TIP4Q (Transferable Intermolecular Potential with 4 charges) combined with two models for methane: an all-atom one OPLS-AA (Optimal Parametrization for the Liquid State) and a united-atom one (UA); a correction for the C–O interaction was applied to the latter and used in a third set of simulations. The models were validated by comparison to experimental values of the free energy of hydration at 280, 300, 330 and 370 K, all under a pressure of 1 bar, and to the experimental radial distribution functions at 277, 283 and 291 K, under a pressure of 145 bar. Regardless of the combination rules used for σC,O, good agreement was found, except when the correction to the UA model was applied. Thus, further simulations of the sI hydrate were performed with the united-atom model to compare the thermal expansivity to the experiment. A final set of simulations was done with the UA methane model and the three water models, to study the sI hydrate-liquid water-gas coexistence at 80, 230 and 400 bar. The melting temperatures were compared to the experimental values. The results show the need to perform simulations with various different models to attain a reliable and robust molecular image of the systems of interest.
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48
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Wu JY, Chen LJ, Chen YP, Lin ST. Molecular dynamics study on the nucleation of methane + tetrahydrofuran mixed guest hydrate. Phys Chem Chem Phys 2016; 18:9935-47. [PMID: 26750660 DOI: 10.1039/c5cp06419h] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nucleation of methane (CH4), tetrahydrofuran (THF), and CH4 + THF hydrates are investigated by microsecond MD simulations. These three systems exhibit distinct structural developments in the aqueous phase quantified by the formation of cage structures of hydrogen bonded water molecules. The development of a cluster of cages in the CH4 system is limited by the scarce CH4 molecules in the solution, while in the THF system it is limited by the short lifetime of cages. In the CH4 + THF mixed guest system, a small cluster of caged CH4 molecules can be rapidly stabilized by abundant neighboring cages of THF molecules. Therefore, the induction time of the CH4 + THF mixed guest system is found to be significantly shorter than that of the pure CH4 and pure THF systems. Furthermore, the structure of cages found in the initially formed cage clusters are often different from the typical 5(12)6(n) (n = 0, 2, 3, 4) cages observed in clathrate hydrate systems. The cluster of cages may grow or transform into structure I or II clathrate hydrate in the later stages.
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Affiliation(s)
- Jyun-Yi Wu
- Department of Chemical Engineering, National Taiwan University, Taipei, 10617, Taiwan.
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49
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Evidence for immobile transitional state of water in methane clathrate hydrates grown from surfactant solutions. Chem Eng Sci 2016. [DOI: 10.1016/j.ces.2015.11.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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50
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Li H, Stanwix P, Aman Z, Johns M, May E, Wang L. Raman Spectroscopic Studies of Clathrate Hydrate Formation in the Presence of Hydrophobized Particles. J Phys Chem A 2016; 120:417-24. [DOI: 10.1021/acs.jpca.5b11247] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Huijuan Li
- School
of Chemical Engineering, The University of Queensland, Brisbane, Australia
| | - Paul Stanwix
- School
of Mechanical and Chemical Engineering, The University of Western Australia, Perth, Australia
| | - Zachary Aman
- School
of Mechanical and Chemical Engineering, The University of Western Australia, Perth, Australia
| | - Michael Johns
- School
of Mechanical and Chemical Engineering, The University of Western Australia, Perth, Australia
| | - Eric May
- School
of Mechanical and Chemical Engineering, The University of Western Australia, Perth, Australia
| | - Liguang Wang
- School
of Chemical Engineering, The University of Queensland, Brisbane, Australia
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