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Guest Partitioning in Carbon Monoxide Hydrate by Raman Spectroscopy Claire Petuya, Francoise Damay, David Talaga, and Arnaud Desmedt J. Phys. Chem. C, Just Accepted Manuscript • Publication Date (Web): 02 Jun 2017 Downloaded from http://pubs.acs.org on June 4, 2017
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Guest Partitioning in Carbon Monoxide Hydrate by Raman Spectroscopy Claire Petuya1, Françoise Damay2, David Talaga1, Arnaud Desmedt1*
1
Groupe Spectroscopie Moléculaire - Institut des Sciences Moléculaires - UMR 5255 CNRS-
Univ. Bordeaux- 351, cours de la Libération F-33404 TALENCE Cedex (France). 2
Laboratoire Léon Brillouin UMR 12 CEA-CNRS – Bât. 563 CEA Saclay, 91191 GIF-SUR-
YVETTE Cedex (France).
* Corresponding Author: Email:
[email protected] Phone: ++33 5 4000 2937
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ABSTRACT. Gas hydrates are inclusion compounds composed of a H-bonded water network forming cages, inside of which gaseous (guest) molecules are encapsulated. Depending on the nature and partitioning of the guest molecules, various types of clathrate structures may be formed. In this work we have elucidated the guest partitioning of the CO hydrate, using highresolution Raman microspectroscopy and investigated the impact of pressure-temperature (P-T) conditions onto this partitioning. For the first time, vibrational signatures of CO molecules encapsulated in large cage and small cage are identified. It is also shown that the large cages of the CO hydrate have the ability to easily catch or release CO guest molecules, while the small cages remain single occupied. Moreover, the study of the P-T dependence of the Raman signature demonstrates not only the CO stretching frequency dependence with the cage filling, but also the tuning effect of the cage filling by the P-T conditions of treatment.
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INTRODUCTION Gas hydrates were first synthesized artificially at the beginning of the 20th century, before being discovered on the ocean floor in the natural state. They were first mentioned as such in 1934 by Hammerschimdt1, who discovered natural gas hydrates in a pipeline plug. Since then, applied and fundamental interests for gas hydrates have steadily expanded, to become nowadays an active and extensive research area. In addition to their many applications in the various areas of flow assurance, energy, technology or environment2, gas hydrates also appear to be essential in astrophysics. They are thought to be involved for example in the formation of planetesimals, comets and other planets of our solar system, such as Saturn’s moons Titan3 or Enceladus4,5. The plausible existence of carbon monoxide hydrate is highlighted during the 60’s with the work of Van Cleff and Diepen6,7 and that of Miller8,9. CO gas being one of the predominant form of carbon10, its hydrate form might be an important component of the Solar System11,12. Experimentally, CO hydrate may form in the two most common clathrate structures: cubic type I with a ~ 12 Å (denoted thereafter SI) or cubic type II with a ~17 Å (denoted SII). The SI unit cell contains 2 small cages (denoted SC) and 6 large cages (denoted LC), while the SII one contains 16 SC and 8 LC. Davidson et al.11 have shown that the CO hydrate is preferentially formed with the SI structure, rather than with the SII one, owing to specific guest-host interactions. Moreover, the small cages are preferentially occupied, according to dielectric and NMR measurements13. Recently, Zhu et al14, using neutron diffraction time-dependent measurements, have demonstrated that the SII and SI structures coexisted after 5 weeks at identical formation conditions (173 bars and 243 K), and that pure SII hydrate is obtained by storing the sample at 100 bars and 252 K during 12 weeks. Moreover, increasing the synthesis time (up to 17 weeks) leads to multiple occupancy of SI LC (up to 1.39), as estimated from the
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Rietveld refinement of the CO hydrate. The SII structure is thus thermodynamically favored, while the SI structure is kinetically promoted at the early synthesis stage; the SI-SII transformation is actually driven by large cage filling – a key chemical properties of gas hydrates. From 13C NMR profile analysis13, the relaxation of CO molecules in LC and in SC has been modeled. IR spectroscopy has been used to investigate CO hydrates too15; disentangling the vibrational signatures of CO molecules encapsulated in large and small cages, however, is a “difficult task” according to the authors, as the difference is estimated to be of the order of a wavenumber. The aim of the present investigation was to determine the guest partitioning of CO molecules in the SI structure experimentally, and to reveal the impact of pressure-temperature treatment conditions onto this partitioning, by means of high-resolution Raman scattering – a spectroscopic technique particularly sensitive to various chemical environments in gas hydrates16,17.
EXPERIMENTAL SECTION Sample preparation. For the neutron diffraction experiments, the CO hydrate sample was obtained with a powder of deuterium oxide (99.9% D) and applying a constant CO gas pressure of 200 bar (purity>99.997%) at a temperature maintained at 270 K (±0.5 K). The CO hydrate began to form after ca. 1.5 hour. To convert a large amount of ice into gas hydrate, we let the formation going on during several days. These thermodynamic conditions have been chosen to only form the structure I of the hydrate. After CO hydrate formation at 270 K and 200 bar (point 1 in Figure 1), the sample is first cooled and depressurized to be stored in liquid nitrogen at atmospheric pressure. Concerning the Raman scattering experiments, the CO hydrate was
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formed by using ultra-pure water (Milli-Q quality) and CO gas (purity>99.997%). First of all, the water was injected inside the high-pressure low-temperature sample cell (0.5 cm3 and equipped with a sapphire windows) then cooled until the ice formed. The temperature cell was maintained at 270 K (±0.1 K). Next, a 200 bars CO pressure was applied on ice. The CO hydrate began to form after ca. 1.5 hour. To convert a large amount of ice into clathrate, we leave the formation to continue during a couple of days. Then, the sample was cooled to 150 K (±0.1 K) and pressure was decreased until 60 bars to investigate various thermodynamic conditions. These thermodynamic conditions have been chosen to only form the SI hydrate.
Figure 1: Phase diagram of CO hydrate18,19. Arrows are representative of the history of the pressures and temperatures followed during the P, T dependence experiments.
Neutron powder diffraction. The experiments has been performed at Laboratoire Léon Brillouin at CEA-Saclay using the cold neutron two-axis powder diffractometer G 4-1. Measurements were done with a wavelength of 2.428 Å from 40 to 100 K. Since the instrumental resolution of
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G 4-1 is better at low 2θ diffusion angle (2θ 3.
Figure 5. Temperature (at constant pressure) and pressure (at constant temperature) dependences of the Raman frequency of the CO molecules encapsulated in SC (black circles) and LC (empty circles) of the SI hydrate. As observed in Figure 6, the cage occupancy ratio 3ALC/ASC linearly increases with pressure and temperature. It should be noted that the pressure dependence follows the Langmuir behavior as observed in the case of the SII N2 hydrate28,29. An intriguing observation may be made with respect to the ability of the LC to be filled and emptied by simply varying the P-T conditions. The initial condition of CO hydrate formation (i.e. at T = 270K and P = 200 bar) yields a ratio 3ALC/ASC of 3.55, i.e., with a LC occupancy ALC = 1.18 (Figure 6). Decreasing the pressure down to 60 bar and then cooling the sample down to 150 K, this ratio reaches a value below 3 (Figure 6). At constant temperature (150 K, Figure 4), 3ALC/ASC increases from 2.55 to 3.53 with pressure; LC’s are partially occupied for pressure below ca. 130 bar, while above this threshold, LC’s occupancy increases above 1. In the present experiment, the maximum LC occupancy is
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reached at a pressure of 200 bar and the ratio reaches the value just after formation, i.e. 3.53. At this constant pressure, raising the temperature leads to an increase of the LC’s occupancy up to 4.82 at 270K. It is thus possible to further fill the LCs with respect to the initial formation condition of the SI CO hydrate. This ability to empty and fill the LCs could find its origin in the energy barrier, which is lower for migrations through the LC faces than for migration through the SC faces, as calculated for hydrogen hydrate30,31. The different trends observed in the temperature and pressure dependences of the guest frequencies can now be understood in terms of LC occupancy: in the constant temperature measurements, the LC occupancy is close to 1 (3ALC/ASC ~ 3), so that the vacant volume contained in the LC (owing to the CO molecules small size) compensates for the unit cell shrinkage under increasing pressure. In contrast, in the constant pressure experiment, the LC occupancy, which is significantly greater than 1 (3ALC/ASC > 3), reduces the vacant volume, and the LCTC model applies.
Figure 6. Temperature and pressure dependence of the 3ALC/ASC ratio (see text). The empty circle corresponds to the ratio measured just after hydrate formation.
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CONCLUDING REMARKS The aim of this work was to better understand the guest partitioning in CO hydrate using highresolution Raman microspectroscopy, and to investigate the impact of P-T conditions onto this partitioning. CO hydrate was formed in the SI structure as revealed by neutron powder diffraction. Thanks to the high spectral resolution, we were able for the first time to disentangle the Raman signatures of CO molecules encapsulated either inside the large or small cages of the SI hydrate structure: the stretching mode of CO molecules is observed at a lower wavenumber when hosted in a LC than in a SC. Moreover, the investigation of the pressure and temperature dependence of these Raman signatures evidences that the cage filling of the CO clathrate hydrate strongly depends onto the P-T conditions. It is shown especially that the LC’s of the SI hydrate have the ability to easily catch or release the CO guest molecules, while the SC’s remain single occupied. At low temperature and pressure (typically 150K and 60 bar), it is shown that the LC occupancy is less than one, whereas it reaches 1.6 at high pressure and temperature (typically 270K and 200 bar). Finally, the CO stretching frequency is shown to depend on the LC occupancy, which itself can be tuned by P-T conditions. In the framework of the loose-cage tight-cage model, a looser cage environment yields softer guest frequencies only when the LC are multiple occupied by CO molecules, i.e., only when the vacant volume in the LC is minimized. This work opens up fundamental question about the ability of CO molecule to migrate through the water faces of the cage: this migration phenomenon might involve disrupting cage that could probably be monitor with future vibrational spectroscopic investigations. More generally, such results open new opportunities not only for the detection of CO hydrate in the solar system (e.g. spectral signature of encapsulated CO molecules), but also for chemical engineering applications (e.g. CO trapping).
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Supporting Information. Additional Neutron Powder Diffractogram and details about the Raman scattering fitting procedure. Acknowledgement. This paper falls in the frame of MI2C project ANR-15CE29-0016 funded by the French ANR “Agence Nationale de la Recherche”.
REFERENCES (1)
Hammerschmidt, E. G. Formation of Gas Hydrates in Natual Gas Transmission Lines. Ind Eng. Chem. 1934, 26, 851-855.
(2)
Sloan, E. D.; Koh, C. A. Clathrate Hydrates of Natural Gases; CRC Press: Boca Raton, FL 2008.
(3)
Lunine, J. I.; Stevenson, D. J. Clathrate and Ammonia Hydrates at High Pressure: Application to the Origin of Methane on Titan. Icarus 1987, 70, 61-77.
(4)
Kieffer, S. W.; Lu, X.; Bethke, C. M.; Spencer, J. R.; Marshak, S.; Navrotsky, A. A Clathrate Reservoir Hypothesis for Enceladus’ South Polar Plume. Science 2006, 314, 1764-1766.
(5)
Waite, J. H.; Lewis, W. S.; Magee, B. A.; Lunine, J. I.; McKinnon, W. B.; Glein, C. R.; Mousis, O.; Young, D. T.; Brockwell, T.; Westlake, J., et al. Liquid Water on Enceladus from Observation of Ammonia and 40Ar in the Plume. Nature 2009, 460, 487-490.
(6)
Van Cleeff, A.; Diepen, G. A. M. Gas Hydrates of Nitrogen and Oxygen. Recueil 1960, 79, 582-586.
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(7)
Van Cleeff, A.; Diepen, G. A. M. Gas Hydrates of Nitrogen and Oxygen II. Recueil 1965, 84, 1085-1093.
(8)
Miller, S. L. The Occurrence of Gas Hydrates in the Solar System. Proc. Nat. Acad. Sci. U. S. A. 1961, 47, 1798-1808.
(9)
Miller, S. L. In Ices in the solar system; Klinger, J., Benest, D., Dollfus, A., Smoluchowski, R., Eds; Springer: Netherlands, 1985, pp 59-79.
(10) Lewis, J. S.; Prinn, R. G. Kinetic Inhibition of CO and N2 Reduction in the Solar Nebula. Astrophys. J. 1980, 238, 357-364. (11) Davidson, D. W.; Desando, M. A.; Gough, S. R.; Handa, Y. P.; Ratcliffe, C. L.; Ripmeester J. A., Tse, J. S. A Clathrate Hydrate of Carbon Monoxide. Nature 1987, 328, 418-419. (12) Lunine, J. I.; Stevenson, D. J. Thermodynamics of Clathrate Hydrate at Low and High Pressures with Application to the Outer Solar System. Astrophys. J. 1985, 58, 493-531. (13) Desando, M. A.; Handa, Y. P.; Hawkins, R. E.; Ratcliffe, C. I.; Ripmeester, J. A. Dielectric and 13C NMR Studies of the Carbon Monoxide Clathrate Hydrate. J. Inclus. Phenom. Mol. Recogn. Chem. 1990, 8, 3-16. (14) Zhu, J.; Du, S.; Yu, X.; Zhang, J.; Xu, H.; Vogel, S.C.; Germann, T. C.; Francisco, J. S.; Izumi, F.; Momma, K., et al. Encapsulation Kinetics and Dynamics of Carbon Monoxide in Clathrate Hydrate. Nat. Commun. 2014, 5, 4128. (15) Dartois, E. CO Clathrate Hydrate: Near to Mid-IR Spectroscopic Signatures. Icarus 2011, 212, 950-956. (16) Sum, A. K.; Burruss, R. C.; Sloan, E. D. Measurement of Clathrate Hydrates via Raman Spectroscopy. J. Phys. Chem. B 1997, 101, 7371-7377. (17) Chazallon, B.; Noble, J.; Desmedt, A. In Gas Hydrates: From Characterization and Modeling to Applications; Broseta, D., Ruffine, L., Desmedt, A., Eds; Wiley−ISTE: London, 2017; Vol. 1, in press.
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(18) Mohammadi, A. H.; Anderson, R.; Tohidi, B. Carbon Monoxide Clathrate Hydrates: Equilibrium Data and Thermodynamic Modeling. AIChE Journal 2005, 51, 2825-2833. (19) Mohammadi, A. H.; Richon, D. Ice-Clathrate Hydrate-Gas Phase Equilibria for Air, Oxygen, Nitrogen, Carbon Monoxide, Methane or Ethane + Water System. Ind. Eng. Chem. Res. 2010, 49, 3976-3979. (20) Le Bail, A. In Accuracy in Powder Diffraction II: Proceedings of the International Conference May 26-29; Prince, E., Stalick, J. K., Eds; NIST Special Publication, 1992, 846, pp 142-153. (21) Rodriguez-Carvajal, J. In FULLPROF: a Program for Rietveld Refinement and Pattern Matching Analysis. Proceeding of the satellite meeting on powder diffraction of the XV congress of the IUCr, Toulouse, France, 1990. (22) Qin, J.; Kuhs, W. F. Calibration of Raman Quantification Factors of Guest Molecules in Clathrate Hydrates and their Application to Gas Exchange Processes Involving N2. J. Chem. Eng. Data 2015, 60, 369-375. (23) The instrumental factors are identical for CO encapsulated in LC and in SC. (24) Subramanian, S.; Sloan, E.D. Trends in Vibrational Frequencies of Guest Trapped in Clathrate Hydrate Cages. J. Phys. Chem. B 2002, 106, 4348-4355. (25) Schober, H.; Itoh, H.; Klapproth, A.; Chihaia, V.; Kuhs, W.F. Guest-host Coupling and Anharmonocity in Clathrate Hydrates. Eur. Phys. J. E 2003, 12, 41-49. (26) Nakano, S.; Moritoki, M.; Ohgaki, K. High-Pressure Phase Equilibrium and Raman Microprobe Spectroscopic Studies on the Methane Hydrate System. J. Chem. Eng. Data 1999, 44, 254-257. (27) There are 3 times more LC than SC in SI. (28) Kuhs W. F.; Chazallon, B.; Radaelli, P. G.; Pauer, F. Cage Occupancy and Compressibility of Deuterated N2-Clathrate Hydrate by Neutron Diffraction. J. Inc. Phen. Mol. Recog. Chem. 1997, 29, 65-77.
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(29) Chazallon, B.; Kuhs, W. F. In situ Structural Properties of N2-, O2-, and Air-Clathrates by Neutron Diffraction. J. Chem. Phys. 2002, 117, 308-320. (30) Alavi, S.; Ripmeester, J. A. Hydrogen-Gas Migration through Clathrate Hydrate Cages. Angew. Chem. 2007, 119, 6214-6217. (31) Burnham, C. J.; English, N. J. Free-energy Calculations of the Intercage Hopping Barriers of Hydrogen Molecules in Clathrate Hydrates. J. Phys. Chem. C 2016, 120, 16561-16567.
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