1
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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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2
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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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3
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Sharma M, Singh S. Carbon dioxide sequestration in natural gas hydrates - effect of flue and noble gases. Phys Chem Chem Phys 2023; 25:30211-30222. [PMID: 37830431 DOI: 10.1039/d3cp03777k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Clean energy is one of the immediate requirements all over the world to tackle the global energy demands. Natural gas hydrates (NGHs) are one of the proposed alternatives that could be used to extract methane as clean energy and simultaneously sequestrate carbon dioxide. However, the formation of CH4-CO2 mixed hydrates and the first hydrate layer besides the interface reduces the rate of CO2 sequestration and methane extraction in NGHs, and thus, multistep extraction of methane is one of the proposed solutions. We report the atomic level factors that could enhance CO2 sequestration in the newly formed first hydrate layer besides the interface in the presence of flue and noble gases using DFT calculations and molecular dynamics simulations at 250 K and 0.15 kbar. The simulations show the formation of stable dual cages (large-large or small-large) that lead to the formation of a four-caged, Y-shaped cluster (growth synthon) which leads to the formation of a hydrate unit cell in heterogeneous medium. Among the flue and noble gases, only argon forms energetically favorable dual cages with itself and CO2 due to which enhanced CO2 sequestration is observed at different concentrations of Ar and CO2 where the CO2 : Ar (2.5 : 1.5) system shows the best CO2 sequestration in the first layer besides the interface. The results also provide understanding into the previously reported concentration dependent CO2 selectivity in sI hydrates in the presence of third gases (N2 and H2S).
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Affiliation(s)
- Manju Sharma
- School of Chemistry, University of Hyderabad, Hyderabad, 500 046, India.
| | - Satyam Singh
- School of Chemistry, University of Hyderabad, Hyderabad, 500 046, India.
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4
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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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5
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Hao X, Li C, Meng Q, Sun J, Huang L, Bu Q, Li C. Molecular Dynamics Simulation of the Three-Phase Equilibrium Line of CO 2 Hydrate with OPC Water Model. ACS OMEGA 2023; 8:39847-39854. [PMID: 37901483 PMCID: PMC10601413 DOI: 10.1021/acsomega.3c05673] [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: 08/16/2023] [Accepted: 09/26/2023] [Indexed: 10/31/2023]
Abstract
The three-phase coexistence line of the CO2 hydrate was determined using molecular dynamics (MD) simulations. By using the classical and modified Lorentz-Berthelot (LB) parameters, the simulations were carried out at 10 different pressures from 3 to 500 MPa. For the OPC water model, simulations with the classic and the modified LB parameters both showed negative deviations from the experimental values. For the TIP4P/Ice water model, good agreement with experimental equilibrium data can be achieved when the LB parameter is adjusted based on the solubility of CO2 in water. Our results also show that the influence of the water model on the equilibrium prediction is much larger than the CO2 model. Current simulations indicated that the H2O-H2O and H2O-CO2 cross-interactions' parameters might contribute equally to the accurate prediction of T3. According to our simulations, the prediction of T3 values showed relatively higher accuracy while using the combination of TIP4P/Ice water and EPM2 CO2 with modified LB parameter. Furthermore, varied χ values are recommended for accurate T3 estimation over a wide pressure range. The knowledge obtained in this study will be helpful for further accurate MD simulation of the process of CO2/CH4 replacement.
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Affiliation(s)
- Xiluo Hao
- Key
Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266071, China
- Laboratory
for Marine Mineral Resources, Laoshan Laboratory, Qingdao 266071, China
| | - Chengfeng Li
- Key
Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266071, China
- Laboratory
for Marine Mineral Resources, Laoshan Laboratory, Qingdao 266071, China
| | - Qingguo Meng
- Key
Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266071, China
- Laboratory
for Marine Mineral Resources, Laoshan Laboratory, Qingdao 266071, China
| | - Jianye Sun
- Key
Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266071, China
- Laboratory
for Marine Mineral Resources, Laoshan Laboratory, Qingdao 266071, China
| | - Li Huang
- Key
Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266071, China
- Laboratory
for Marine Mineral Resources, Laoshan Laboratory, Qingdao 266071, China
| | - Qingtao Bu
- Key
Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, Qingdao 266071, China
- Laboratory
for Marine Mineral Resources, Laoshan Laboratory, Qingdao 266071, China
| | - Congying Li
- Center
of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
- Laboratory
for Marine Mineral Resources, Laoshan Laboratory, Qingdao 266071, China
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6
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Guerra A, Mathews S, Su JT, Marić M, Servio P, Rey AD. Molecular dynamics predictions of transport properties for carbon dioxide hydrates under pre-nucleation conditions using TIP4P/Ice water and EPM2, TraPPE, and Zhang carbon dioxide potentials. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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7
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Arjun A, Bolhuis PG. Homogeneous nucleation of crystalline methane hydrate in molecular dynamics transition paths sampled under realistic conditions. J Chem Phys 2023; 158:044504. [PMID: 36725504 DOI: 10.1063/5.0124852] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Methane hydrates are important from a scientific and industrial perspective, and form by nucleation and growth from a supersaturated aqueous solution of methane. Molecular simulation is able to shed light on the process of homogeneous nucleation of hydrates, using straightforward molecular dynamics or rare event enhanced sampling techniques with atomistic and coarse grained force fields. In our previous work [Arjun, T. A. Berendsen, and P. G. Bolhuis, Proc. Natl. Acad. Sci. U. S. A. 116, 19305 (2019)], we performed transition path sampling (TPS) simulations using all atom force fields under moderate driving forces at high pressure, which enabled unbiased atomistic insight into the formation of methane hydrates. The supersaturation in these simulations was influenced by the Laplace pressure induced by the spherical gas reservoir. Here, we investigate the effect of removing this influence. Focusing on the supercooled, supersaturated regime to keep the system size tractable, our TPS simulations indicate that nuclei form amorphous structures below roughly 260 K and crystalline sI structures above 260 K. For these temperatures, the average transition path lengths are significantly longer than in our previous study, pushing the boundaries of what can be achieved with TPS. The temperature to observe a critical nucleus of certain size was roughly 20 K lower compared to a spherical reservoir due to the lower concentration of methane in the solution, yielding a reduced driving force. We analyze the TPS results using a model based on classical nucleation theory. The corresponding free energy barriers are estimated and found to be consistent with previous predictions, thus adding to the overall picture of the hydrate formation process.
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Affiliation(s)
- A Arjun
- van 't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands
| | - Peter G Bolhuis
- van 't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands
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8
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Yang P, Guo D, Fang B. Dynamic Dissociation Behaviors of sII Hydrates in Liquid Water by Heating: A Molecular Dynamics Simulation Approach. ACS OMEGA 2022; 7:42774-42782. [PMID: 36467936 PMCID: PMC9713880 DOI: 10.1021/acsomega.2c04488] [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: 07/16/2022] [Accepted: 11/02/2022] [Indexed: 06/17/2023]
Abstract
An understanding of the dynamic behavior of subtle hydrate dissociation in the liquid water phase is fundamental for gas production from marine hydrate reservoirs. Molecular dynamics simulations are performed in this study to investigate the dissociation kinetics of pure propane and binary propane + methane sII hydrates in a liquid water environment. The results show that faster hydrate dissociation rates are observed at higher initial temperatures. The hydrate phase dissociates from the cluster surface to the inside in a layer-by-layer manner under the simulation temperature conditions, which is similar to the behavior of sI hydrates and is independent of the hydrate crystal type. Compared to the binary sII hydrate, the pure sII hydrate dissociates more easily under the same initial temperature conditions, which can be attributed to the stabilizing effect of guest molecules in the hydrate cages. The empty cages collapse in one step, in contrast to the two-step pathway induced by the guest-host interaction. In addition, a hydrocarbon phase forms in the binary hydrate dissociation system instead of nanobubbles. These results can provide molecular-level insights into the dynamic mechanism of hydrate dissociation and theoretical guidance for gas recovery by thermal injection from marine hydrate reservoirs.
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Affiliation(s)
- Peihan Yang
- School
of Mathematics and Physics, China University
of Geosciences, Wuhan430074, China
| | - Dongdong Guo
- School
of Earth and Environment, Anhui University
of Science & Technology, Huainan232001, China
| | - Bin Fang
- School
of Mathematics and Physics, China University
of Geosciences, Wuhan430074, China
- Process
and Energy Department, Delft University
of Technology, Leeghwaterstraat
39, 2628CBDelft, The Netherlands
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9
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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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10
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Guerra A, Mathews S, Marić M, Servio P, Rey AD. All-Atom Molecular Dynamics of Pure Water-Methane Gas Hydrate Systems under Pre-Nucleation Conditions: A Direct Comparison between Experiments and Simulations of Transport Properties for the Tip4p/Ice Water Model. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27155019. [PMID: 35956968 PMCID: PMC9370622 DOI: 10.3390/molecules27155019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 07/29/2022] [Accepted: 08/02/2022] [Indexed: 11/24/2022]
Abstract
(1) Background: New technologies involving gas hydrates under pre-nucleation conditions such as gas separations and storage have become more prominent. This has necessitated the characterization and modeling of the transport properties of such systems. (2) Methodology: This work explored methane hydrate systems under pre-nucleation conditions. All-atom molecular dynamics simulations were used to quantify the performance of the TIP4P/2005 and TIP4P/Ice water models to predict the viscosity, diffusivity, and thermal conductivity using various formulations. (3) Results: Molecular simulation equilibrium was robustly demonstrated using various measures. The Green–Kubo estimation of viscosity outperformed other formulations when combined with TIP4P/Ice, and the same combination outperformed all TIP4P/2005 formulations. The Green–Kubo TIP4P/Ice estimation of viscosity overestimates (by 84% on average) the viscosity of methane hydrate systems under pre-nucleation conditions across all pressures considered (0–5 MPag). The presence of methane was found to increase the average number of hydrogen bonds over time (6.7–7.8%). TIP4P/Ice methane systems were also found to have 16–19% longer hydrogen bond lifetimes over pure water systems. (4) Conclusion: An inherent limitation in the current water force field for its application in the context of transport properties estimations for methane gas hydrate systems. A re-parametrization of the current force field is suggested as a starting point. Until then, this work may serve as a characterization of the deviance in viscosity prediction.
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11
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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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12
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Molecular Mechanism of Organic Crystal Nucleation: A Perspective of Solution Chemistry and Polymorphism. CRYSTALS 2022. [DOI: 10.3390/cryst12070980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Crystal nucleation determining the formation and assembly pathway of first organic materials is the central science of various scientific disciplines such as chemical, geochemical, biological, and synthetic materials. However, our current understanding of the molecular mechanisms of nucleation remains limited. Over the past decades, the advancements of new experimental and computational techniques have renewed numerous interests in detailed molecular mechanisms of crystal nucleation, especially structure evolution and solution chemistry. These efforts bifurcate into two categories: (modified) classical nucleation theory (CNT) and non-classical nucleation mechanisms. In this review, we briefly introduce the two nucleation mechanisms and summarize current molecular understandings of crystal nucleation that are specifically applied in polymorphic crystallization systems of small organic molecules. Many important aspects of crystal nucleation including molecular association, solvation, aromatic interactions, and hierarchy in intermolecular interactions were examined and discussed for a series of organic molecular systems. The new understandings relating to molecular self-assembly in nucleating systems have suggested more complex multiple nucleation pathways that are associated with the formation and evolution of molecular aggregates in solution.
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13
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Hao X, Li C, Liu C, Meng Q, Sun J. The performance of OPC water model in prediction of the phase equilibria of methane hydrate. J Chem Phys 2022; 157:014504. [DOI: 10.1063/5.0093659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular dynamics (MD) simulations were performed to determine the three-phase coexistence line of sI methane hydrates. The MD simulations were carried out at four different pressures (4, 10, 40 and 100 MPa) by using direct phase coexistence method. In current simulations, water was described by either TIP4P/Ice or OPC models and methane was described as a simple Lennard-Jones (LJ) interaction site. Lorentz-Berthelot combining rules were used to calculate the parameters of the cross interactions. For OPC model, positive deviations from the energetic Lorentz-Berthelot rule were also considered based on the solubility of methane in water. For TIP4P/Ice water model, the obtained three phase coexistence temperatures showed good agreement with experiment data at higher pressures, which is consistent with previous predictions. For OPC water model, simulations using the classic and the modified LB parameters both showed negative deviations to the experimental values. Our results also indicated that the deviation of the T3 prediction by OPC model not much correlated with the predicted melting point of ice. At 4 MPa, the modified OPC model showed outstanding prediction of hydrate equilibrium temperature, even better than the prediction by TIP4P/Ice. The relative higher accuracy in biomolecular MD of OPC model suggests that this model may have a better performance in hydrate MD simulations of biomolecule-based additives.
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Affiliation(s)
- Xiluo Hao
- Qingdao Institute of Marine Geology, China
| | | | | | | | - Jianye Sun
- Qingdao Institute of Marine Geology, China
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14
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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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15
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16
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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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17
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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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18
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Li K, Wang P, Tang L, Shi R, Su Y, Zhao J. Stability and NMR Chemical Shift of Amorphous Precursors of Methane Hydrate: Insights from Dispersion-Corrected Density Functional Theory Calculations Combined with Machine Learning. J Phys Chem B 2021; 125:431-441. [PMID: 33356268 DOI: 10.1021/acs.jpcb.0c09162] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Clathrate hydrates of natural gases are important backup energy sources. It is thus of great significance to explore the nucleation process of hydrates. Hydrate clusters are building blocks of crystalline hydrates and represent the initial stage of hydrate nucleation. Using dispersion-corrected density functional theory (DFT-D) combined with machine learning, herein, we systematically investigate the evolution of stabilities and nuclear magnetic resonance (NMR) chemical shifts of amorphous precursors from monocage clusters CH4(H2O)n (n = 16-24) to decacage clusters (CH4)10(H2O)n (n = 121-125). Compared with planelike configurations, the close-packed structures formed by the water-cage clusters are energetically favorable. The 512 cages are dominant, and the emerging amorphous precursors may be part of sII hydrates at the initial stage of nucleation. Based on our data set, the possible initial fusion pathways for water-cage clusters are proposed. In addition, the 13C NMR chemical shifts for encapsulated methane molecules also showed regular changes during the fusion of water-cage clusters. Machine learning can reproduce the DFT-D results well, providing a structure-energy-property landscape that could be used to predict the energy and NMR chemical shifts of such multicages with more water molecules. These theoretical results present vital insights into the hydrate nucleation from a unique perspective.
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Affiliation(s)
- Keyao Li
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, China
| | - Pengju Wang
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, China
| | - Lingli Tang
- School of Science, Dalian Minzu University, Dalian 116600, China
| | - Ruili Shi
- School of Mathematics and Physics, Hebei University of Engineering, Handan 056038, China
| | - Yan Su
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, China
| | - Jijun Zhao
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, China
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19
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Arjun A, Bolhuis PG. Molecular Understanding of Homogeneous Nucleation of CO 2 Hydrates Using Transition Path Sampling. J Phys Chem B 2021; 125:338-349. [PMID: 33379869 PMCID: PMC7816195 DOI: 10.1021/acs.jpcb.0c09915] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/11/2020] [Indexed: 11/29/2022]
Abstract
Carbon dioxide hydrate is a solid built from hydrogen-bond stabilized water cages that encapsulate individual CO2 molecules. As potential candidates for reducing greenhouse gases, hydrates have attracted attention from both the industry and scientific community. Under high pressure and low temperature, hydrates are formed spontaneously from a mixture of CO2 and water via nucleation and growth. Yet, for moderate undercooling, i.e., moderate supersaturation, studying hydrate formation with molecular simulations is very challenging due to the high nucleation barriers involved. We investigate the homogeneous nucleation mechanism of CO2 hydrate as a function of temperature using transition path sampling (TPS), which generates ensembles of unbiased dynamical trajectories across the high barrier between the liquid and solid states. The resulting path ensembles reveal that at high driving force (low temperature), amorphous structures are predominantly formed, with 4151062 cages being the most abundant. With increasing temperature, the nucleation mechanism changes, and 51262 becomes the most abundant cage type, giving rise to the crystalline sI structure. Reaction coordinate analysis can reveal the most important collective variable involved in the mechanism. With increasing temperature, we observe a shift from a single feature (size of the nucleus) to a 2-dimensional (size and cage type) variable as the salient ingredient of the reaction coordinate, and then back to only the nucleus size. This finding is in line with the underlying shift from an amorphous to a crystalline nucleation channel. Modeling such complex phase transformations using transition path sampling gives unbiased insight into the molecular mechanisms toward different polymorphs, and how these are determined by thermodynamics and kinetics. This study will be beneficial for researchers aiming to produce such hydrates with different polymorphic forms.
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Affiliation(s)
- A. Arjun
- van ’t Hoff Institute
for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090 GD Amsterdam, The Netherlands
| | - P. G. Bolhuis
- van ’t Hoff Institute
for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090 GD Amsterdam, The Netherlands
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20
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Kirova EM, Pisarev VV. Morphological aspect of crystal nucleation in wall-confined supercooled metallic film. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 33:034003. [PMID: 33078713 DOI: 10.1088/1361-648x/abba6b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 09/21/2020] [Indexed: 06/11/2023]
Abstract
In this paper, we simulate the nucleation and growth of crystalline nuclei in a molybdenum film cooled at different rates confined between two amorphous walls. We also compare the results for the wall-confined and wall-free systems. We apply the same methodology as in the work (Kirova and Pisarev 2019J. Cryst. Growth528125266) which is based on reconstructing the probability density function for the largest crystalline nucleus in the system. The size of the nucleus and the asphericity parameter are considered as the reaction coordinates. We demonstrate that in both the free and confined systems there are two mechanisms of crystal growth: the attachment of atoms to the biggest crystal from the amorphous phase and the merging of the biggest crystal cluster with small ones (coalescence). We show that the attachment mechanism is dominant in the melt cooled down at a slower rate, and the mechanism gradually shifts to coalescence as cooling rate increases. We also observe the formation of long-lived crystal clusters and demonstrate that amorphous walls do not affect their geometric characteristics. However, system confined between walls demonstrates higher glass-forming ability.
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Affiliation(s)
- E M Kirova
- National Research University Higher School of Economics, 20 Myasnitskaya str., 101000 Moscow, Russia
- Joint Institute for High Temperatures of RAS, 13/2 Izhorskaya str., 125412 Moscow, Russia
| | - V V Pisarev
- National Research University Higher School of Economics, 20 Myasnitskaya str., 101000 Moscow, Russia
- Joint Institute for High Temperatures of RAS, 13/2 Izhorskaya str., 125412 Moscow, Russia
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21
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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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22
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Arjun A, Bolhuis PG. Rate Prediction for Homogeneous Nucleation of Methane Hydrate at Moderate Supersaturation Using Transition Interface Sampling. J Phys Chem B 2020; 124:8099-8109. [PMID: 32803974 PMCID: PMC7503527 DOI: 10.1021/acs.jpcb.0c04582] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The crystallization of methane hydrates via homogeneous nucleation under natural, moderate conditions is of both industrial and scientific relevance, yet still poorly understood. Predicting the nucleation rates at such conditions is notoriously difficult due to high nucleation barriers, and requires, besides an accurate molecular model, enhanced sampling. Here, we apply the transition interface sampling technique, which efficiently computes the exact rate of nucleation by generating ensembles of unbiased dynamical trajectories crossing predefined interfaces located between the stable states. Using an accurate atomistic force field and focusing on specific conditions of 280 K and 500 bar, we compute for nucleation directly into the sI crystal phase at a rate of ∼10-17 nuclei per nanosecond per simulation volume or ∼102 nuclei per second per cm3, in agreement with consensus estimates for nearby conditions. As this is most likely fortuitous, we discuss the causes of the large differences between our results and previous simulation studies. Our work shows that it is now possible to compute rates for methane hydrates at moderate supersaturation, without relying on any assumptions other than the force field.
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Affiliation(s)
- A Arjun
- van 't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090 GD Amsterdam, The Netherlands
| | - P G Bolhuis
- van 't Hoff Institute for Molecular Sciences, University of Amsterdam, PO Box 94157, 1090 GD Amsterdam, The Netherlands
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23
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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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24
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Unbiased atomistic insight in the competing nucleation mechanisms of methane hydrates. Proc Natl Acad Sci U S A 2019; 116:19305-19310. [PMID: 31501333 PMCID: PMC6765301 DOI: 10.1073/pnas.1906502116] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mixtures of methane gas and water can form ice-like solid methane hydrates via homogeneous nucleation at natural, moderate conditions. Understanding the formation of the different hydrate polymorphs, required for improved control of crystallization, is hampered by limited experimental resolution. Direct molecular dynamics simulations could provide insight, but it would require computation times beyond the age of the Universe for a single nucleation event to take place. Yet, the nucleation event itself, while rare, occurs fast. Therefore, we sample and examine ensembles of rare unbiased nucleation trajectories. Detailed analysis shows how selection between competing amorphous and crystalline polymorph formation mechanisms takes place. The conclusions shed light onto the formation of clathrate hydrates. Methane hydrates have important industrial and climate implications, yet their formation via homogeneous nucleation under natural, moderate conditions is poorly understood. Obtaining such understanding could lead to improved control of crystallization, as well as insight into polymorph selection in general, but is hampered by limited experimental resolution. Direct molecular dynamics simulations using atomistic force fields could provide such insight, but are not feasible for moderate undercooling, due to the rare event nature of nucleation. Instead, we harvest ensembles of the rare unbiased nucleation trajectories by employing transition path sampling. We find that with decreasing undercooling the mechanism shifts from amorphous to crystalline polymorph formation. At intermediate temperature the 2 mechanisms compete. Reaction coordinate analysis reveals the amount of a specific methane cage type is crucial for crystallization, while irrelevant for amorphous solids. Polymorph selection is thus governed by kinetic accessibility of the correct cage type and, moreover, occurs at precritical nucleus sizes, apparently against Ostwald’s step rule. We argue that these results are still in line with classical nucleation theory. Our findings illuminate how selection between competing methane hydrate polymorphs occurs and might generalize to other hydrates and molecular crystal formation.
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25
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Yagasaki T, Matsumoto M, Tanaka H. Liquid-liquid separation of aqueous solutions: A molecular dynamics study. J Chem Phys 2019; 150:214506. [DOI: 10.1063/1.5096429] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Takuma Yagasaki
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Masakazu Matsumoto
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Hideki Tanaka
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
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26
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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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27
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Hall KW, Percec S, Klein ML. Polymer nucleation under high-driving force, long-chain conditions: Heat release and the separation of time scales. J Chem Phys 2019; 150:114901. [PMID: 30902014 DOI: 10.1063/1.5084773] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
This study reveals important features of polymer crystal formation at high-driving forces in entangled polymer melts based on simulations of polyethylene. First and in contrast to small-molecule crystallization, the heat released during polymer crystallization does not appreciably influence structural details of early-stage, crystalline clusters (crystal nuclei). Second, early-stage polymer crystallization (crystal nucleation) can occur without substantial chain-level relaxation and conformational changes. This study's results indicate that local structures and environments guide crystal nucleation in entangled polymer melts under high-driving force conditions. Given that such conditions are often used to process polyethylene, local structures and the separation of time scales associated with crystallization and chain-level processes are anticipated to be of substantial importance to processing strategies. This study highlights new research directions for understanding polymer crystallization.
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Affiliation(s)
- Kyle Wm Hall
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Simona Percec
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Michael L Klein
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
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28
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Hall KW, Zhang Z, Burnham CJ, Guo GJ, Carpendale S, English NJ, Kusalik PG. Does Local Structure Bias How a Crystal Nucleus Evolves? J Phys Chem Lett 2018; 9:6991-6998. [PMID: 30484659 DOI: 10.1021/acs.jpclett.8b03115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The broad scientific and technological importance of crystallization has led to significant research probing and rationalizing crystal nucleation processes. Previous work has generally neglected the possibility of the molecular-level dynamics of individual crystal nuclei coupling to local structures. However, recent experimental work has conjectured that this can occur. Therefore, to address a deficiency in scientific understanding of crystallization, we have probed the nucleation of prototypical single and multicomponent crystals (specifically, ice and mixed gas hydrates). We establish that local structures can bias the evolution of nascent crystal phases on a nanosecond time scale by, for example, promoting the appearance or disappearance of specific crystal motifs and thus reveal a new facet of crystallization behavior. Moreover, we demonstrate structural biases are likely present during crystallization processes beyond ice and gas hydrate formation. Structurally biased dynamics are a lens for understanding existing computational and experimental results while pointing to future opportunities.
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Affiliation(s)
- Kyle Wm Hall
- Department of Chemistry , University of Calgary , Calgary , Alberta T2N 1N4 , Canada
- Department of Computer Science , University of Calgary , Calgary , Alberta T2N 1N4 , Canada
| | - Zhengcai Zhang
- Department of Chemistry , University of Calgary , Calgary , Alberta T2N 1N4 , Canada
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics , Chinese Academy of Sciences , Beijing 100029 , China
| | - Christian J Burnham
- School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 , Ireland
| | - Guang-Jun Guo
- Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics , Chinese Academy of Sciences , Beijing 100029 , China
- College of Earth Science , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Sheelagh Carpendale
- Department of Computer Science , University of Calgary , Calgary , Alberta T2N 1N4 , Canada
| | - Niall J English
- School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 , Ireland
| | - Peter G Kusalik
- Department of Chemistry , University of Calgary , Calgary , Alberta T2N 1N4 , Canada
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29
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Dehabadi L, Karoyo AH, Wilson LD. Spectroscopic and Thermodynamic Study of Biopolymer Adsorption Phenomena in Heterogeneous Solid-Liquid Systems. ACS OMEGA 2018; 3:15370-15379. [PMID: 31458195 PMCID: PMC6643837 DOI: 10.1021/acsomega.8b01663] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 10/29/2018] [Indexed: 05/24/2023]
Abstract
Molecular selective adsorption processes at the solid surface of biopolymers in mixed solvent systems are poorly understood due to manifold interactions. However, the ability to achieve adsorptive fractionation of liquid mixtures is posited to relate to the role of specific solid-liquid interactions at the adsorbent interface. The hydration of solid biopolymers (amylose, amylopectin, cellulose) in binary aqueous systems is partly governed by the relative solvent binding affinities with the biopolymer surface sites, in accordance with the role of textural and surface chemical properties. While molecular models that account for the surface area and solvent effects provide reliable estimates of hydration energy and binding affinity parameters, spectroscopic and thermal methods offer a facile alternative experimental approach to account for detailed aspects of solvation phenomena at biopolymer interfaces that involve solid-liquid adsorption. In this report, thermal and spectroscopic methods were used to understand the interaction of starch- and cellulose-based materials in water-ethanol (W-E) binary mixtures. Batch adsorption studies in binary W-E mixtures reveal the selective solvent uptake properties by the biomaterials, in agreement with their solvent swelling in pure water or ethanol. The nature, stability of the bound water, and the thermodynamic properties of the biopolymers in variable hydration states were probed via differential scanning calorimetry and Raman spectroscopy. The trends in biopolymer-solvent interactions are corroborated by dye adsorption and scanning electron microscopy, indicating that biopolymer adsorption properties in W-E mixtures strongly depend on the surface area, pore structure, and accessibility of the polar surface groups of the biopolymer systems, in agreement with the solvent-selective uptake results reported herein.
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30
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Tanaka H, Yagasaki T, Matsumoto M. On the phase behaviors of hydrocarbon and noble gas clathrate hydrates: Dissociation pressures, phase diagram, occupancies, and equilibrium with aqueous solution. J Chem Phys 2018; 149:074502. [DOI: 10.1063/1.5044568] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Hideki Tanaka
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Takuma Yagasaki
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Masakazu Matsumoto
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
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31
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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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32
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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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33
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DeFever RS, Sarupria S. Nucleation mechanism of clathrate hydrates of water-soluble guest molecules. J Chem Phys 2017; 147:204503. [DOI: 10.1063/1.4996132] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ryan S. DeFever
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, USA
| | - Sapna Sarupria
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, USA
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34
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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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35
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Nada H. Anisotropy in geometrically rough structure of ice prismatic plane interface during growth: Development of a modified six-site model of H 2O and a molecular dynamics simulation. J Chem Phys 2017; 145:244706. [PMID: 28049310 DOI: 10.1063/1.4973000] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
This paper presents a modified version of the six-site model of H2O [H. Nada and J. P. J. M. van der Eerden, J. Chem. Phys. 118, 7401 (2003)]. Although the original six-site model was optimized by assuming the cut-off of the Coulomb interaction at an intermolecular distance of 10 Å, the modified model is optimized by using the Ewald method for estimating the Coulomb interaction. Molecular dynamics (MD) simulations of an ice-water interface suggest that the melting point of ice at 1 atm in the modified model is approximately 274.5 K, in good agreement with the real melting point of 273.15 K. MD simulations of bulk ice and water suggest that the modified model reproduces not only the structures and density curves of ice and water, but also the diffusion coefficient of water molecules in water near the melting point at 1 atm. Using the modified model, a large-scale MD simulation of the growth at an ice-water interface of the prismatic plane is performed to elucidate the anisotropy in the interface structure during growth. Simulation results indicate that the geometrical roughness of the ice growth front at the interface is greater in the c-axis direction than in the direction normal to the c-axis when it is analyzed along the axes parallel to the prismatic plane. In addition, during the growth at the interface, the transient appearance of specific crystallographic planes, such as a {202¯1} pyramidal plane, occurs preferentially at the ice growth front. The effect of different ensembles with different simulation systems on the anisotropy in the interface structure is also investigated.
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Affiliation(s)
- Hiroki Nada
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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36
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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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37
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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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38
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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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39
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Sosso G, Chen J, Cox SJ, Fitzner M, Pedevilla P, Zen A, Michaelides A. Crystal Nucleation in Liquids: Open Questions and Future Challenges in Molecular Dynamics Simulations. Chem Rev 2016; 116:7078-116. [PMID: 27228560 PMCID: PMC4919765 DOI: 10.1021/acs.chemrev.5b00744] [Citation(s) in RCA: 390] [Impact Index Per Article: 48.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Indexed: 11/28/2022]
Abstract
The nucleation of crystals in liquids is one of nature's most ubiquitous phenomena, playing an important role in areas such as climate change and the production of drugs. As the early stages of nucleation involve exceedingly small time and length scales, atomistic computer simulations can provide unique insights into the microscopic aspects of crystallization. In this review, we take stock of the numerous molecular dynamics simulations that, in the past few decades, have unraveled crucial aspects of crystal nucleation in liquids. We put into context the theoretical framework of classical nucleation theory and the state-of-the-art computational methods by reviewing simulations of such processes as ice nucleation and the crystallization of molecules in solutions. We shall see that molecular dynamics simulations have provided key insights into diverse nucleation scenarios, ranging from colloidal particles to natural gas hydrates, and that, as a result, the general applicability of classical nucleation theory has been repeatedly called into question. We have attempted to identify the most pressing open questions in the field. We believe that, by improving (i) existing interatomic potentials and (ii) currently available enhanced sampling methods, the community can move toward accurate investigations of realistic systems of practical interest, thus bringing simulations a step closer to experiments.
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Affiliation(s)
- Gabriele
C. Sosso
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
| | - Ji Chen
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
| | | | - Martin Fitzner
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
| | - Philipp Pedevilla
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
| | - Andrea Zen
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
| | - Angelos Michaelides
- Thomas Young Centre, London
Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street WC1E
6BT London, U.K.
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40
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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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41
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Zeng Q, Li J, Huang H, Wang X, Yang M. Polarization response of clathrate hydrates capsulated with guest molecules. J Chem Phys 2016; 144:204308. [PMID: 27250307 DOI: 10.1063/1.4952417] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Clathrate hydrates are characterized by their water cages encapsulating various guest atoms or molecules. The polarization effect of these guest-cage complexes was studied with combined density functional theory and finite-field calculations. An addition rule was noted for these systems whose total polarizability is approximately equal to the polarizability sum of the guest and the cage. However, their distributional polarizability computed with Hirshfeld partitioning scheme indicates that the guest-cage interaction has considerable influence on their polarization response. The polarization of encapsulated guest is reduced while the polarization of water cage is enhanced. The counteraction of these two opposite effects leads to the almost unchanged total polarizability. Further analysis reveals that the reduced polarizability of encapsulated guest results from the shielding effect of water cage against the external field and the enhanced polarizability of water cage from the enhanced bonding of hydrogen bonds among water molecules. Although the charge transfer through the hydrogen bonds is rather small in the water cage, the polarization response of clathrate hydrates is sensitive to the changes of hydrogen bonding strength. The guest encapsulation strengthens the hydrogen bonding network and leads to enhanced polarizability.
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Affiliation(s)
- Qun Zeng
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
| | - Jinshan Li
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
| | - Hui Huang
- Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
| | - Xinqin Wang
- Institute of Atomic and Molecular Physics, Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610065, People's Republic of China
| | - Mingli Yang
- Institute of Atomic and Molecular Physics, Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610065, People's Republic of China
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42
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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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43
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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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44
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Liu C, Zhang Z, Guo GJ. Effect of guests on the adsorption interaction between a hydrate cage and guests. RSC Adv 2016. [DOI: 10.1039/c6ra21513k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A criterion is proposed to judge which guest can enter the cage through which face.
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Affiliation(s)
- Chanjuan Liu
- Key Laboratory of Earth and Planetary Physics
- Institute of Geology and Geophysics
- Chinese Academy of Sciences
- Beijing 100029
- China
| | - 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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45
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Yagasaki T, Matsumoto M, Tanaka H. Effects of thermodynamic inhibitors on the dissociation of methane hydrate: a molecular dynamics study. Phys Chem Chem Phys 2015; 17:32347-57. [PMID: 26587576 DOI: 10.1039/c5cp03008k] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the effects of methanol and NaCl, which are known as thermodynamic hydrate inhibitors, on the dissociation kinetics of methane hydrate in aqueous solutions by using molecular dynamics simulations. It is shown that the dissociation rate is not constant but changes with time. The dissociation rate in the initial stage is increased by methanol whereas it is decreased by NaCl. This difference arises from the opposite effects of the two thermodynamic inhibitors on the hydration free energy of methane. The dissociation rate of methane hydrate is increased by the formation of methane bubbles in the aqueous phase because the bubbles absorb surrounding methane molecules. It is found that both methanol and NaCl facilitate the bubble formation. However, their mechanisms are completely different from each other. The presence of ions enhances the hydrophobic interactions between methane molecules. In addition, the ions in the solution cause a highly non-uniform distribution of dissolved methane molecules. These two effects result in the easy formation of bubbles in the NaCl solution. In contrast, methanol assists the bubble formation because of its amphiphilic character.
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Affiliation(s)
- Takuma Yagasaki
- Department of Chemistry, Faculty of Science, Okayama University, Okayama, 700-8530, Japan
| | - Masakazu Matsumoto
- Department of Chemistry, Faculty of Science, Okayama University, Okayama, 700-8530, Japan
| | - Hideki Tanaka
- Department of Chemistry, Faculty of Science, Okayama University, Okayama, 700-8530, Japan and Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama, 700-8530, Japan.
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46
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Małolepsza E, Keyes T. Pathways through Equilibrated States with Coexisting Phases for Gas Hydrate Formation. J Phys Chem B 2015; 119:15857-65. [DOI: 10.1021/acs.jpcb.5b06832] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Edyta Małolepsza
- Department
of Chemistry, Boston University, Boston, Massachusetts 02215-2521, United States
| | - Tom Keyes
- Department
of Chemistry, Boston University, Boston, Massachusetts 02215-2521, United States
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47
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Yagasaki T, Matsumoto M, Tanaka H. Adsorption Mechanism of Inhibitor and Guest Molecules on the Surface of Gas Hydrates. J Am Chem Soc 2015; 137:12079-85. [DOI: 10.1021/jacs.5b07417] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Takuma Yagasaki
- Department
of Chemistry, Faculty of Science, Okayama University, Okayama, 700-8530, Japan
| | - Masakazu Matsumoto
- Department
of Chemistry, Faculty of Science, Okayama University, Okayama, 700-8530, Japan
| | - Hideki Tanaka
- Department
of Chemistry, Faculty of Science, Okayama University, Okayama, 700-8530, Japan
- Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama, 700-8530, Japan
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