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Yamaoka S, Hyeon-Deuk K. Decelerated Liquid Dynamics Induced by Component-Dependent Supercooling in Hydrogen and Deuterium Quantum Mixtures. J Phys Chem Lett 2020; 11:4186-4192. [PMID: 32375000 DOI: 10.1021/acs.jpclett.0c00801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Isotopic mixtures of p-H2 and o-D2 molecules have been an attractive binary system because they include two kinds of purely isotopic molecules which possess the same electronic potential but the twice different mass inducing differently pronounced nuclear quantum effects (NQEs). Accessing details of structures and dynamics in such quantum mixtures combining complex molecular dynamics with NQEs of different strengths remains a challenging problem. Taking advantage of the nonempirical molecular dynamics method which describes p-H2 and o-D2 molecules, we found that the liquid dynamics slows down at a specific mixing ratio, which can be connected to the observed anomalous slowdown of crystallization in the quantum mixtures. We attributed the decelerated dynamics to the component-dependent supercooling of p-H2 taking place in the mixtures, demonstrating that there is an optimal mixing ratio to hinder crystallization. The obtained physical insights will help in experimentally controlling and achieving unknown quantum mixtures including superfluid.
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Affiliation(s)
- Shutaro Yamaoka
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan
| | - Kim Hyeon-Deuk
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan
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2
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Zhong H, Li L, Ma R, Zhong J, Yan Y, Li S, Zhang J, Liu J. Two-dimensional hydrogen hydrates: structure and stability. Phys Chem Chem Phys 2020; 22:5774-5784. [PMID: 32104817 DOI: 10.1039/c9cp06296c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structure and stability of two-dimensional hydrogen hydrate were investigated in this work using density functional theory. The results are in line with expectations that the occupied cages are more stable after their confinement between two parallel hydrophobic sheets. The four two-dimensional hydrogen hydrate crystals - BLHH-I, BLHH-II, BLHH-III and BLHH-IV - that we predicted were much more stable in a restricted environment than in a free environment, even close to or exceeding conventional hydrogen hydrates. Besides, we found that the stability of two-dimensional hydrates is inversely related to the increase in temperature. Our work highlights that two-dimensional hydrates provide a new research idea in the field of hydrogen storage.
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Affiliation(s)
- Hong Zhong
- College of Science, China University of Petroleum, Qingdao, 266580, China
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3
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Mojica-Sánchez JP, Zarate-López TI, Flores-Álvarez JM, Reyes-Gómez J, Pineda-Urbina K, Gómez-Sandoval Z. Magnesium oxide clusters as promising candidates for hydrogen storage. Phys Chem Chem Phys 2019; 21:23102-23110. [DOI: 10.1039/c9cp05075b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A magnesium oxide candidate for hydrogen storage is identified through Born–Oppenheimer molecular dynamics.
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Affiliation(s)
- Juan Pablo Mojica-Sánchez
- Instituto Tecnológico José Mario Molina Pasquel y Henríquez Campus Tamazula de Gordiano
- Tamazula de Gordiano
- Mexico
- Facultad de Ciencias Químicas
- Universidad de Colima
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4
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Alavi S, Ripmeester JA. Simulations of hydrogen gas in clathrate hydrates. MOLECULAR SIMULATION 2017. [DOI: 10.1080/08927022.2017.1295456] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Saman Alavi
- National Research Council of Canada, Ottawa, Canada
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada
| | - John A. Ripmeester
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada
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5
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Atamas AA, Cuppen HM, Koudriachova MV, de Leeuw SW. Monte Carlo calculations of the free energy of binary sII hydrogen clathrate hydrates for identifying efficient promoter molecules. J Phys Chem B 2013; 117:1155-65. [PMID: 23289842 DOI: 10.1021/jp306585t] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The thermodynamics of binary sII hydrogen clathrates with secondary guest molecules is studied with Monte Carlo simulations. The small cages of the sII unit cell are occupied by one H(2) guest molecule. Different promoter molecules entrapped in the large cages are considered. Simulations are conducted at a pressure of 1000 atm in a temperature range of 233-293 K. To determine the stabilizing effect of different promoter molecules on the clathrate, the Gibbs free energy of fully and partially occupied sII hydrogen clathrates are calculated. Our aim is to predict what would be an efficient promoter molecule using properties such as size, dipole moment, and hydrogen bonding capability. The gas clathrate configurational and free energies are compared. The entropy makes a considerable contribution to the free energy and should be taken into account in determining stability conditions of binary sII hydrogen clathrates.
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Affiliation(s)
- Alexander A Atamas
- Theoretical Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
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6
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Sarupria S, Debenedetti PG. Molecular Dynamics Study of Carbon Dioxide Hydrate Dissociation. J Phys Chem A 2011; 115:6102-11. [DOI: 10.1021/jp110868t] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sapna Sarupria
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Pablo G. Debenedetti
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
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7
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Frankcombe TJ, Kroes GJ. A new method for screening potential sII and sH hydrogen clathrate hydrate promoters with model potentials. Phys Chem Chem Phys 2011; 13:13410-20. [DOI: 10.1039/c0cp02702b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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Valdés Á, Kroes GJ. Translation-rotation energy levels of one H2molecule inside the small, medium and large cages of the structure H clathrate hydrate. Phys Chem Chem Phys 2011; 13:2935-44. [DOI: 10.1039/c0cp01804j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Álvaro Valdés
- Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA, Leiden.
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9
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Papadimitriou N, Tsimpanogiannis I, Stubos A. Monte Carlo study of sI hydrogen hydrates. MOLECULAR SIMULATION 2010. [DOI: 10.1080/08927021003752796] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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10
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Asare E, Musah AR, Curotto E, Freeman DL, Doll JD. The thermodynamic and ground state properties of the TIP4P water octamer. J Chem Phys 2009; 131:184508. [DOI: 10.1063/1.3259047] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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11
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Sum AK, Koh CA, Sloan ED. Clathrate Hydrates: From Laboratory Science to Engineering Practice. Ind Eng Chem Res 2009. [DOI: 10.1021/ie900679m] [Citation(s) in RCA: 300] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Amadeu K. Sum
- Center for Hydrate Research, Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado 80401
| | - Carolyn A. Koh
- Center for Hydrate Research, Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado 80401
| | - E. Dendy Sloan
- Center for Hydrate Research, Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado 80401
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12
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Tribello GA, Slater B. A theoretical examination of known and hypothetical clathrate hydrate materials. J Chem Phys 2009; 131:024703. [DOI: 10.1063/1.3142503] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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13
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Martín Á, Peters CJ. Hydrogen Storage in sH Clathrate Hydrates: Thermodynamic Model. J Phys Chem B 2009; 113:7558-63. [DOI: 10.1021/jp8074578] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ángel Martín
- Faculty of Mechanical, Maritime and Materials Engineering, Department of Process and Energy, Laboratory of Process Equipment, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft, The Netherlands, and The Petroleum Institute, Department of Chemical Engineering, P.O. Box 2533, Abu Dhabi, United Arab Emirates
| | - Cor J. Peters
- Faculty of Mechanical, Maritime and Materials Engineering, Department of Process and Energy, Laboratory of Process Equipment, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft, The Netherlands, and The Petroleum Institute, Department of Chemical Engineering, P.O. Box 2533, Abu Dhabi, United Arab Emirates
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14
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Mohammadi-Manesh H, Alavi S, Woo TK, Ashrafizaadeh M, Najafi B. Molecular dynamics simulation of 13C NMR powder lineshapes of CO in structure I clathrate hydrate. Phys Chem Chem Phys 2009; 11:8821-8. [DOI: 10.1039/b905233j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Papadimitriou N, Tsimpanogiannis I, Papaioannou A, Stubos A. Monte Carlo study of sII and sH argon hydrates with multiple occupancy of cages. MOLECULAR SIMULATION 2008. [DOI: 10.1080/08927020802101734] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- N.I. Papadimitriou
- a Environmental Research Laboratory , National Center for Scientific Research ‘Demokritos’ , Agia Paraskevi, 15310, Greece
| | - I.N. Tsimpanogiannis
- a Environmental Research Laboratory , National Center for Scientific Research ‘Demokritos’ , Agia Paraskevi, 15310, Greece
| | - A.Th. Papaioannou
- b School of Chemical Engineering, National Technical University of Athens , Zografou, 15780, Greece
| | - A.K. Stubos
- a Environmental Research Laboratory , National Center for Scientific Research ‘Demokritos’ , Agia Paraskevi, 15310, Greece
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16
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Papadimitriou NI, Tsimpanogiannis IN, Peters CJ, Papaioannou AT, Stubos AK. Hydrogen Storage in sH Hydrates: A Monte Carlo Study. J Phys Chem B 2008; 112:14206-11. [DOI: 10.1021/jp805906c] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- N. I. Papadimitriou
- Environmental Research Laboratory, National Center for Scientific Research “Demokritos”, 15310 Agia Paraskevi, Greece, School of Chemical Engineering, National Technical University of Athens, Heroon Polytechniou 9, 15780 Zografou, Greece, and Laboratory of Process Equipment, Department of Process and Energy, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft, The Netherlands
| | - I. N. Tsimpanogiannis
- Environmental Research Laboratory, National Center for Scientific Research “Demokritos”, 15310 Agia Paraskevi, Greece, School of Chemical Engineering, National Technical University of Athens, Heroon Polytechniou 9, 15780 Zografou, Greece, and Laboratory of Process Equipment, Department of Process and Energy, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft, The Netherlands
| | - C. J. Peters
- Environmental Research Laboratory, National Center for Scientific Research “Demokritos”, 15310 Agia Paraskevi, Greece, School of Chemical Engineering, National Technical University of Athens, Heroon Polytechniou 9, 15780 Zografou, Greece, and Laboratory of Process Equipment, Department of Process and Energy, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft, The Netherlands
| | - A. Th. Papaioannou
- Environmental Research Laboratory, National Center for Scientific Research “Demokritos”, 15310 Agia Paraskevi, Greece, School of Chemical Engineering, National Technical University of Athens, Heroon Polytechniou 9, 15780 Zografou, Greece, and Laboratory of Process Equipment, Department of Process and Energy, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft, The Netherlands
| | - A. K. Stubos
- Environmental Research Laboratory, National Center for Scientific Research “Demokritos”, 15310 Agia Paraskevi, Greece, School of Chemical Engineering, National Technical University of Athens, Heroon Polytechniou 9, 15780 Zografou, Greece, and Laboratory of Process Equipment, Department of Process and Energy, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft, The Netherlands
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17
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Alavi S, Dornan P, Woo TK. Determination of NMR lineshape anisotropy of guest molecules within inclusion complexes from molecular dynamics simulations. Chemphyschem 2008; 9:911-9. [PMID: 18386265 DOI: 10.1002/cphc.200700805] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Nonspherical cages in inclusion compounds can result in non-uniform motion of guest species in these cages and anisotropic lineshapes in NMR spectra of the guest. Herein, we develop a methodology to calculate lineshape anisotropy of guest species in cages based on molecular dynamics simulations of the inclusion compound. The methodology is valid for guest atoms with spin 1/2 nuclei and does not depend on the temperature and type of inclusion compound or guest species studied. As an example, the nonspherical shape of the structure I (sI) clathrate hydrate large cages leads to preferential alignment of linear CO(2) molecules in directions parallel to the two hexagonal faces of the cages. The angular distribution of the CO(2) guests in terms of a polar angle theta and azimuth angle phi and small amplitude vibrational motions in the large cage are characterized by molecular dynamics simulations at different temperatures in the stability range of the CO(2) sI clathrate. The experimental (13)C NMR lineshapes of CO(2) guests in the large cages show a reversal of the skew between the low temperature (77 K) and the high temperature (238 K) limits of the stability of the clathrate. We determine the angular distributions of the guests in the cages by classical MD simulations of the sI clathrate and calculate the (13)C NMR lineshapes over a range of temperatures. Good agreement between experimental lineshapes and calculated lineshapes is obtained. No assumptions regarding the nature of the guest motions in the cages are required.
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Affiliation(s)
- Saman Alavi
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
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18
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Strobel TA, Koh CA, Sloan ED. Water Cavities of sH Clathrate Hydrate Stabilized by Molecular Hydrogen. J Phys Chem B 2008; 112:1885-7. [DOI: 10.1021/jp7110549] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Timothy A. Strobel
- Colorado School of Mines, Chemical Engineering Department, Golden, Colorado 80401
| | - Carolyn A. Koh
- Colorado School of Mines, Chemical Engineering Department, Golden, Colorado 80401
| | - E. Dendy Sloan
- Colorado School of Mines, Chemical Engineering Department, Golden, Colorado 80401
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19
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Dornan P, Alavi S, Woo TK. Free energies of carbon dioxide sequestration and methane recovery in clathrate hydrates. J Chem Phys 2007; 127:124510. [PMID: 17902924 DOI: 10.1063/1.2769634] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Classical molecular dynamics simulations are used to compare the stability of methane, carbon dioxide, nitrogen, and mixed CO(2)N(2) structure I (sI) clathrates under deep ocean seafloor temperature and pressure conditions (275 K and 30 MPa) which were considered suitable for CO(2) sequestration. Substitution of methane guests in both the small and large sI cages by CO(2) and N(2) fluids are considered separately to determine the separate contributions to the overall free energy of substitution. The structure I clathrate with methane in small cages and carbon dioxide in large cages is determined to be the most stable. Substitutions of methane in the small cages with CO(2) and N(2) have positive free energies. Substitution of methane with CO(2) in the large cages has a large negative free energy and substitution of the methane in the large cages with N(2) has a small positive free energy. The calculations show that under conditions where storage is being considered, carbon dioxide spontaneously replaces methane from sI clathrates, causing the release of methane. This process must be considered if there are methane clathrates present where CO(2) sequestration is to be attempted. The calculations also indicate that N(2) does not directly compete with CO(2) during methane substitution or clathrate formation and therefore can be used as a carrier gas or may be present as an impurity. Simulations further reveal that the replacement of methane with CO(2) in structure II (sII) cages also has a negative free energy. In cases where sII CO(2) clathrates are formed, only single occupancy of the large cages will be observed.
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Affiliation(s)
- Peter Dornan
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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20
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Struzhkin VV, Militzer B, Mao WL, Mao HK, Hemley RJ. Hydrogen Storage in Molecular Clathrates. Chem Rev 2007; 107:4133-51. [PMID: 17850164 DOI: 10.1021/cr050183d] [Citation(s) in RCA: 327] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Viktor V Struzhkin
- Carnegie Institution of Washington, Geophysical Laboratory, 5251 Broad Branch Road, NW, Washington, DC 20015, USA
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22
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Alavi S, Ripmeester JA. Hydrogen-Gas Migration through Clathrate Hydrate Cages. Angew Chem Int Ed Engl 2007; 46:6102-5. [PMID: 17623283 DOI: 10.1002/anie.200700250] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Saman Alavi
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada.
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Miyoshi T, Imai M, Ohmura R, Yasuoka K. Thermodynamic stability of type-I and type-II clathrate hydrates depending on the chemical species of the guest substances. J Chem Phys 2007; 126:234506. [PMID: 17600424 DOI: 10.1063/1.2746324] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The free energy differences are calculated for various type-I and type-II clathrate hydrates based on molecular-dynamics simulations, thereby evaluating the thermodynamic stability of the hydrates depending on the chemical species of the guest substances. The simulation systems consist of 27 unit cells, that is, 1242 water molecules and 216 guest molecules for type-I hydrates, and 3672 water molecules and 648 guest molecules for type-II hydrates. The water molecules are described by TIP4P potential, while the guest molecules are described by one-site Lennard-Jones potential, U=4epsilon{(sigma/r)12-(sigma/r)6}, where U is the potential energy, r is the particle distance, sigma is the particle diameter, and epsilon is the energy well depth. The optimal values of sigma that yield the minimum free energy (the best thermodynamic stability) were determined to be 0.39 nm for the type-I hydrates and 0.37 nm for the type-II hydrates.
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Affiliation(s)
- Tatsuya Miyoshi
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
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Alavi S, Ripmeester JA, Klug DD. Molecular dynamics study of the stability of methane structure H clathrate hydrates. J Chem Phys 2007; 126:124708. [PMID: 17411153 DOI: 10.1063/1.2710261] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Molecular dynamics simulations are used to study the stability of structure H (sH) methane clathrate hydrates in a 3 x 3 x 3 sH unit cell replica. Simulations are performed at experimental conditions of 300 K and 2 GPa for three methane intermolecular potentials. The five small cages of the sH unit cell are assigned methane guest occupancies of one and large cage guest occupancies of one to five are considered. Radial distribution functions, unit cell volumes, and configurational energies are studied as a function of large cage CH(4) occupancy. Free energy calculations are carried out to determine the stability of clathrates for large cage occupancies. Large cage occupancy of five is the most stable configuration for a Lennard-Jones united-atom potential and the Tse-Klein-McDonald potential parametrized for condensed methane phases and two for the most stable configuation for the Murad and Gubbins potential.
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Affiliation(s)
- Saman Alavi
- Department of Chemistry, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
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Alavi S, Woo TK. How much carbon dioxide can be stored in the structure H clathrate hydrates?: A molecular dynamics study. J Chem Phys 2007; 126:044703. [PMID: 17286495 DOI: 10.1063/1.2424936] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The stability of structure H (sH) carbon dioxide clathrate hydrates at three temperature-pressure conditions are determined by molecular dynamics simulations on a 3x3x3 sH unit cell replica. Simulations are performed at 100 K at ambient pressure, 273 K at 100 bars and also 300 K and 5.0 kbars. The small and medium cages of the sH unit cell are occupied by a single carbon dioxide guest and large cage guest occupancies of 1-5 are considered. Radial distribution functions are given for guests in the large cages and unit cell volumes and configurational energies are studied as a function of large cage CO(2) occupancy. Free energy calculations are carried out to determine the stability of clathrates for large cage occupancies at three temperature/pressure conditions stated above. At the low temperature, large cage occupancy of 5 is the most stable while at the higher temperature, the occupancy of 3 is the most favored. Calculations are also performed to show that the CO(2) sH clathrate is more stable than the methane clathrate analog. Implications on CO(2) sequestration by clathrate formation are discussed.
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Affiliation(s)
- Saman Alavi
- Department of Chemistry, University of Ottawa, Ottawa, Ontario KIN 6N5, Canada.
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Alavi S, Ripmeester JA, Klug DD. Stability of rare gas structure H clathrate hydrates. J Chem Phys 2006; 125:104501. [PMID: 16999535 DOI: 10.1063/1.2238864] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Molecular dynamics simulations are used to study the stability of structure H (sH) clathrate hydrates with the rare gases Ne, Ar, Kr, and Xe. Simulations on a 3 x 3 x 3 sH unit cell replica are performed at ambient pressure at 40 and 100 K temperatures. The small and medium (s+m) cages of the sH unit cell are assigned rare gas guest occupancies of 1 and for large (l) cages guest occupancies of 1-6 are considered. Radial distribution functions for guest pairs with occupancies in the l-l, l-(s+m), and (s+m)-(s+m) cages are presented. The unit cell volumes and configurational energies are studied as a function of large cage occupancy for the rare gases. Free energy calculations are carried out to determine the stability of clathrates for large cage occupancies at 100 K and 1 bar and 20 kbar pressures. These studies show that the most stable argon clathrate has five guests in the large cages. For krypton and xenon the most stable configurations have three and two guests in the large cages, respectively.
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Affiliation(s)
- Saman Alavi
- Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada.
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