Semiclathrate hydrate dissociation conditions measured for the systems including CO2, N2, CH4, or H2 + tetra-n-butylammonium bromide (TBAB) aqueous solution with a wide range of concentrations (0.050, 0.100, 0.150, 0.153, 0.167, 0.250, 0.350, and 0.500 mass fraction) are reported. These data were measured in a (277.7 to 294.7) K temperature range and pressures up to 15.49 MPa pursuing an isochoric pressure search method. Some comparisons are made between our data and the experimental phase equilibrium data reported in open literature. The comparisons show that some literature data seem to be not reliable.

Publication Date (Web): March 24, 2011International audienceA detailed description of an experimental setup based on the "static-analytic" technique with gas phase capillary sampling designed, built, and improved "in-house" to measure phase equilibria (pressure, temperature, and compositions) under gas hydrate formation conditions is presented in this work. The apparatus is suitable for measurements at temperatures ranging from 233 to 373 K and pressures up to 60 MPa. It was used to study phase equilibria in the carbon dioxide + methane + water system under hydrate formation conditions. An isochoric pressure-search method was used to measure hydrate dissociation conditions. The experimental data have been compared successfully with the literature data. The compositions of the gas phase in equilibrium with the hydrate and aqueous phases were measured using a gas chromatography technique and compared successfully with the literature data. The compositions of the hydrate and aqueous phases were determined by applying material balance equations. The experimental data on the compositions of the hydrate have been compared successfully with the literature data. To solve the latter equations, the Newton's numerical method coupled with the differential evolution optimization strategy was employed. All the aforementioned experimental data (hydrate dissociation conditions + composition analyses) have been compared with the predictions of two thermodynamic models, namely CSMGem and HWHYD. A discussion is made on the reliability of the predictions of the latter models

Publication Date (Web): March 11, 2011International audienceIn this article, experimental data on compositions of equilibrium phases under gas hydrate formation conditions are reported for the carbon dioxide + nitrogen + water system in the (273.6 to 281.7) K temperature range for pressures up to 17.628 MPa. An experimental "in-house" setup based on the "static-analytic" technique was employed for performing the measurements. An isochoric pressure-search method in combination with gas phase compositional analysis was used to measure compositions of the gas phase in equilibrium with gas hydrate and liquid water. A material balance method was used to determine compositions of the hydrate and aqueous phases. A mathematical approach based on the Newton's numerical method and the Differential Evolution optimization strategy was applied to solve the material balance equations. The compositional data generated in this work are compared with the corresponding experimental data reported in the literature as well as the predictions of the CSMGem thermodynamic model

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