Measurement and prediction of dissociation pressures of isobutane and propane hydrates below the ice point

Holder, Gerald D.; Godbole, S.P.

doi:10.1002/aic.690280607

Cited by 56 publications

(36 citation statements)

References 14 publications

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“…The experimental data on dissociation pressures is obtained from Holder and Godbole. 47 The Journal of Physical Chemistry C Article predictions from the rigid-lattice approximation are closer to simulations because of fortuitous cancellation of errors.…”

Section: Resultsmentioning

confidence: 99%

Improving the Rigor and Consistency of the Thermodynamic Theory for Clathrate Hydrates through Incorporation of Movement of Water Molecules of Hydrate Lattice

Ravipati

Punnathanam

2015

J. Phys. Chem. C

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Current applications of statistical thermodynamic theories for clathrate hydrates do not incorporate the translational and rotational movement of water molecules of the hydrate lattice in a rigorous manner. Previous studies have shown that the movement of water molecules has a significant effect on the properties of clathrate hydrates. In this Article, a method is presented to incorporate the effect of water movement with as much rigor as possible. This method is then used to calculate the Langmuir constant of the guest species in a clathrate hydrate. Unlike previous studies on modeling of clathrate hydrate thermodynamics, the method presented in this paper does not regress either the intermolecular potentials or the properties of the empty hydrate from clathrate phase equilibria data. Also the properties of empty hydrate used in the theory do not depend on the nature and composition of the guest molecules. The predicted phase equilibria from the resulting theory are shown to be highly accurate and thermodynamically consistent by comparing them with the phase equilibria computed directly from molecular simulations.

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Section: Resultsmentioning

confidence: 99%

Improving the Rigor and Consistency of the Thermodynamic Theory for Clathrate Hydrates through Incorporation of Movement of Water Molecules of Hydrate Lattice

Ravipati

Punnathanam

2015

J. Phys. Chem. C

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“…The power of the microwave was set at 0.01 mW for all ESR measurements and the signals of both butyl radicals observed in the present study are unsaturated at the power of 0.01 mW, because the saturation points of isobutyl and tert-butyl radicals at 120 K are located at 2 and 0.3 mW, respectively. In isothermal annealing experiments, the annealing and measurement temperature range was 240 K to 265 K. The equilibrium temperature of simple isobutane hydrate prepared with H 2 O at ambient pressure is approximately 272 K [12,13]. Generally, the equilibrium temperature of hydrate prepared with D 2 O is 2-4 K higher than that of H 2 O [14].…”

Section: Methodsmentioning

confidence: 99%

Intermolecular Hydrogen Transfer in Isobutane Hydrate

et al. 2012

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Electron spin resonance (ESR) spectra of butyl radicals induced with γ-ray irradiation in the simple isobutane (2-methylpropane) hydrate (prepared with deuterated water) were investigated. Isothermal annealing results of the γ-ray-irradiated isobutane hydrate reveal that the isobutyl radical in a large cage withdraws a hydrogen atom from the isobutane molecule through shared hexagonal-faces of adjacent large cages. During this "hydrogen picking" process, the isobutyl radical is apparently transformed into a tert-butyl radical, while the sum of isobutyl and tert-butyl radicals remains constant. The apparent transformation from isobutyl to tert-butyl radicals is an irreversible first-order reaction and the activation energy was estimated to be 35 ± 3 kJ/mol, which was in agreement with the activation energy (39 ± 5 kJ/mol) of hydrogen picking in the γ-ray-irradiated propane hydrate with deuterated water.

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“…The phase equilibrium condition of carbon dioxide hydrate was measured with the isochoric pressure search method [35,36]. The stainless steel cell has a fixed volume of about 25 cm 3 .…”

Section: Experimental Apparatusmentioning

confidence: 99%

Phase equilibria of CO2 hydrate in NaCl–MgCl2 aqueous solutions

Zha

Liang

2012

The Journal of Chemical Thermodynamics

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a b s t r a c tPhase equilibrium data for CO 2 hydrate in presence of binary NaCl-MgCl 2 aqueous solutions were obtained at four different concentrations (2 wt%NaCl-8 wt%MgCl 2 , 8 wt%NaCl-2 wt%MgCl 2 , 5 wt% NaCl-15 wt%MgCl 2 , 15 wt% NaCl-5 wt%MgCl 2 ) in the temperature range of (258.63 to 276.45) K and in the pressure range of (1.34 to 3.41) MPa, respectively. The measurements were carried out by employing isochoric pressure search method with uncertainties of ±0.1 K for temperature and ±0.02 MPa for pressure. The hydrate equilibrium data for the (CO 2 + water) system were compared with some experimental data from the literature, and the acceptable agreement demonstrated the reliability of the experimental method used in this work. The van der Waals and Platteeuw (vdW-P) solid solution theory was used to model the hydrate phase, and the equation of Weiss combined with Pitzer-based model was applied to characterize the activity of water. The predicted results were in good consistency with the experimental data, and the average pressure deviation was 5.13%.

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Measurement and prediction of dissociation pressures of isobutane and propane hydrates below the ice point

Cited by 56 publications

References 14 publications

Improving the Rigor and Consistency of the Thermodynamic Theory for Clathrate Hydrates through Incorporation of Movement of Water Molecules of Hydrate Lattice

Improving the Rigor and Consistency of the Thermodynamic Theory for Clathrate Hydrates through Incorporation of Movement of Water Molecules of Hydrate Lattice

Intermolecular Hydrogen Transfer in Isobutane Hydrate

Phase equilibria of CO2 hydrate in NaCl–MgCl2 aqueous solutions

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