The Minimal Occupancy Level of the Clathrate Hydrate Host Lattice and the Intercalation Heat of the Guest Molecules in the Chlorine Hydrates

2011 ◽  
Vol 638 (2) ◽  
pp. 279-281
Author(s):  
László Kótai ◽  
Szabolcs Bálint ◽  
István Gács ◽  
Györgyi Lakatos ◽  
András Angyal ◽  
...  
Keyword(s):  
Host Lattice ◽  
Clathrate Hydrate ◽  
Guest Molecules

Clathrate and other solid phases in the tetrahydrofuran–water system: thermal conductivity and heat capacity under pressure

1982 ◽  
Vol 60 (7) ◽  
pp. 881-892 ◽  
Author(s):  
Russell G. Ross ◽  
Per Andersson
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Water System ◽  
Clathrate Hydrate ◽  
Transient Hot Wire ◽  
Guest Molecules ◽  
Hydrate Phase ◽  
Wire Method ◽  
Solid Phases ◽  
Thermal Conductivity Λ

Solid phases in the tetrahydrofuran–water (THF–H2O) system were investigated in the temperature range 100–260 K and at pressures up to 1.5 GPa. Thermal conductivity, λ, and heat capacity per unit volume, ρcp, were measured, using the transient hot-wire method. We made measurements on solid phases having nominal compositions THF•17H2O, THF•7•1H2O, and THF•4•6H2O, which we refer to as phases α, β, and γ, respectively. Phase α is known to be a structure II clathrate hydrate, and λ for this phase was found to be similar to other crystalline solids which are glass-like in relation to their thermal properties. Low-energy excitations are known to be relevant to the properties of glass-like solids, and, in the case of phase α, were probably rotational vibrations of the THF guest molecules. Phase β was similar, and we inferred that it was probably a structure I clathrate hydrate. Phase γ behaved nearly like a normal crystal phase at low temperatures, but λ became almost independent of temperature near melting. At 1.1 GPa and 130 K, we found evidence that phase α transformed, on pressurization, to a metastable modification which may be a new high-density form of clathrate hydrate. The astrophysical implications of our results were mentioned briefly.

Comments on the Infrared Spectra of SO2 Clathrate-hydrate Formed by Vapor Condensation

1971 ◽  
Vol 49 (24) ◽  
pp. 4114-4115 ◽  
Author(s):  
A. H. Hardin ◽  
K. B. Harvey
Keyword(s):  
Amorphous Phase ◽  
Infrared Spectra ◽  
Transformation Temperature ◽  
Vapor Condensation ◽  
Clathrate Hydrate ◽  
Hindered Rotation ◽  
Guest Molecules ◽  
Gaseous Mixtures

Gaseous mixtures having clathrate-hydrate stoichiometries were condensed at 83 °K into an amorphous phase. Infrared spectra were recorded at a series of temperatures up to 180 °K in order to determine the transformation temperature and the nature of the annealed phase. Bands associated with the H2O molecules began to shift position at 125 °K while those attributed to guest molecules decreased to null intensity. There was no evidence of a unique clathrate-hydrate H2O spectrum nor of free or hindered rotation of the guest molecules.

Two terphenyl-based diol hosts and corresponding solvent inclusions with dimethylformamide and acetonitrile

2015 ◽  
Vol 71 (9) ◽  
pp. 768-775
Author(s):  
Hendrik Klien ◽  
Wilhelm Seichter ◽  
Konstantinos Skobridis ◽  
Edwin Weber
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Solvent Molecule ◽  
Intramolecular Hydrogen Bonding ◽  
Host Lattice ◽  
Solvent Free ◽  
Guest Molecules ◽  
Solvent Molecules ◽  
Intramolecular Hydrogen ◽  
Supramolecular Aggregates

Having reference to an elongated structural modification of 2,2′-bis(hydroxydiphenylmethyl)biphenyl, (I), the two 1,1′:4′,1′′-terphenyl-based diol hosts 2,2′′-bis(hydroxydiphenylmethyl)-1,1′:4′,1′′-terphenyl, C44H34O2, (II), and 2,2′′-bis[hydroxybis(4-methylphenyl)methyl]-1,1′:4′,1′′-terphenyl, C48H42O2, (III), have been synthesized and studied with regard to their crystal structures involving different inclusions,i.e.(II) with dimethylformamide (DMF), C44H34O2·C2H6NO, denoted (IIa), (III) with DMF, C48H42O2·C2H6NO, denoted (IIIa), and (III) with acetonitrile, C48H42O2·CH3CN, denoted (IIIb). In the solvent-free crystals of (II) and (III), the hydroxy H atoms are involved in intramolecular O—H...π hydrogen bonding, with the central arene ring of the terphenyl unit acting as an acceptor. The corresponding crystal structures are stabilized by intermolecular C—H...π contacts. Due to the distinctive acceptor character of the included DMF solvent species in the crystal structures of (IIa) and (IIIa), the guest molecule is coordinated to the hostviaO—H...O=C hydrogen bonding. In both crystal structures, infinite strands composed of alternating host and guest molecules represent the basic supramolecular aggregates. Within a given strand, the O atom of the solvent molecule acts as a bifurcated acceptor. Similar to the solvent-free cases, the hydroxy H atoms in inclusion structure (IIIb) are involved in intramolecular hydrogen bonding, and there is thus a lack of host–guest interaction. As a result, the solvent molecules are accommodated as C—H...N hydrogen-bonded inversion-symmetric dimers in the channel-like voids of the host lattice.

Observation of Electric-Field-Induced Liberation of Guest Molecules from Clathrate Hydrate

2021 ◽  
pp. 10410-10416
Author(s):  
Ziyue Li ◽  
Mengjie Lyu ◽  
Hannes Jónsson ◽  
Christoph Rose-Petruck
Keyword(s):  
Electric Field ◽  
Clathrate Hydrate ◽  
Guest Molecules

On the thermodynamic stability of clathrate hydrates

2003 ◽  
Vol 81 (1-2) ◽  
pp. 55-60 ◽  
Author(s):  
H Tanaka
Keyword(s):  
Free Energy ◽  
Thermodynamic Stability ◽  
Vibrational Frequency ◽  
Host Lattice ◽  
Clathrate Hydrates ◽  
Total Free Energy ◽  
Guest Molecules ◽  
Free Energy Of Formation ◽  
Entropic Contribution ◽  
Energy Of Formation

The thermodynamic stability of clathrate hydrates is investigated by theoretically examining the free energy of formation of clathrate hydrates encaging propane and argon. The total free energy is divided into several contributions: the interaction between water and guest molecules, the entropic contribution arising from the combinations of cage occupancy, and the free energy due to intermolecular vibrations. The method introduced here removes some of the assumptions of the van der Waals and Platteeuw theory. It is shown that the shift of the vibrational frequency of the host lattice destabilizes the clathrate hydrates thermodynamically. PACS No.: 61.50Ah

scholarly journals Does cage quantum delocalisation influence the translation–rotational bound states of molecular hydrogen in clathrate hydrate?

2018 ◽  
Vol 212 ◽  
pp. 533-546 ◽  
Author(s):  
David M. Benoit ◽  
David Lauvergnat ◽  
Yohann Scribano
Keyword(s):  
Molecular Hydrogen ◽  
Bound States ◽  
Clathrate Hydrate ◽  
Guest Molecules

In this study, we examine the effect of a flexible description of the clathrate hydrate framework on the translation–rotation (TR) eigenstates of guest molecules such as molecular hydrogen.

Structural Transition of Trimethylamine Hydrate by Methane or Hydrogen Inclusion

2020 ◽  
Author(s):  
Minjun Cha
Keyword(s):  
Structural Transition ◽  
Guest Molecule ◽  
Clathrate Hydrate ◽  
Hydrogen Gas ◽  
Time Dependent ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Inclusion Process ◽  
Diffraction Patterns

<p>Recently, several alkylamine hydrates have been studied in an effort to reveal the structural transitions from semi- to ‘canonical’ clathrate hydrate in the presence of secondary guest molecules. Trimethylamine (TMA) is known to form the semi-clathrate hydrate, and it has been reported that the structural transition of the TMA semi-clathrate hydrate may not occur in the presence of hydrogen gas as a secondary guest molecule. This paper reports the structural transition of trimethylamine(TMA) hydrate induced by the type of guest molecules. Powder X-ray diffraction patterns of (TMA + H<sub>2</sub>) hydrates show the formation of hexagoanl P6/mmm hydrate, but those of (TMA + CH<sub>4</sub>) hydrates indicate the formation of cubic Fd3m hydrate. Without gaseous guest molecule, the crystal structure of pure TMA hydrate is identified as hexagonal P6/mmm. Therefore, inclusion of gaseous methane in TMA hydrate can induce the structural transition from hexagonal to cubic hydrate or the formation of metastable cubic hydrate. To clearly reveal this possibility, we also check the time-dependent structural patterns of binary (TMA + CH<sub>4</sub>) hydrates from 1 to 14 days, and the results show that the structural transition of TMA hydrate from hexagonal P6/mmm to cubic Fd3m hydrate structure can occur during the methane inclusion process.</p>

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