Yutaek Seo

Thermodynamic measurements and NMR spectroscopic analysis were used to show that it is possible to recover CO2 from flue gas by forming a mixed hydrate that removes CO2 preferentially from CO2/N2 gas mixtures using water dispersed in the pores of silica gel. Kinetic studies with 1H NMR microimaging showed that the dispersed water in the silica gel pore system reacts readily with the gas, thus obviating the need for a stirred reactor and excess water. Hydrate phase equilibria for the ternary CO2-

Three-phase equilibria for the carbon dioxide + methane + water system were obtained by employing the isobaric temperature search method. Based on these isobaric hydrate equilibrium studies, the ternary hydrate, water-rich liquid, and vapor equilibrium lines generated at different compositions of carbon dioxide and methane were all located between two three-phase equilibrium lines of simple hydrates formed by a single guest component. The upper quadruple points where the four phases hydrate, wat

Three-phase equilibria consisting of vapor, water-rich liquid, and solid hydrate were measured for the aqueous solutions containing two guest molecules of carbon dioxide and methane in the temperature range of 272−284 K and at pressures of 15, 20, 26, 35, and 50 bar. At the specified isobaric condition the three-phase equilibrium temperatures become higher as the relative concentrations of carbon dioxide to methane increase. The upper quadruple points at which the four phases of vapor, water-ric

In this contribution, X-ray diffraction and 13C NMR spectroscopy were used to identify structure and guest distribution of the mixed N2 + CO2 hydrates. X-ray diffraction results of the mixed N2 + CO2 hydrates confirmed that the unit cell parameter was ∼11.8 Å over the gas mixture composition range of 3−20 mol % CO2 and the formed hydrates were identified as structure I. When the composition of the gas mixture was reduced to 1 mol % CO2, the structure of the mixed hydrate was transformed to struc

Hydrate phase equilibria have been measured for carbon dioxide + cyclic ethers + water in the temperature range of (270 to 290) K and in the pressure range of (0.2 to 4.7) MPa. Three cyclic ethers, THF, propylene oxide, and 1,4-dioxane, were selected at a mole fraction of 0.03. The stabilization effect of the mixed hydrate was found to be the highest for THF followed by propylene oxide, while no stabilization effect was observed for 1,4-dioxane in the studied temperature and pressure range. The

Gas hydrates represent an attractive way of storing large quantities of gas such as methane and carbon dioxide, although to date there has been little effort to optimize the storage capacity and to understand the trade-offs between storage conditions and storage capacity. In this work, we present estimates for gas storage based on the ideal structures, and show how these must be modified given the little data available on hydrate composition. We then examine the hypothesis based on solid-solutio

Gas hydrates are becoming an attractive way of storing and transporting large quantities of natural gas, although there has been little effort to understand the preferential occupation of heavy hydrocarbon molecules in hydrate cages. In this work, we present the formation kinetics of mixed hydrate based on a gas uptake measurement during hydrate formation, and how the compositions of the hydrate phase are varied under corresponding formation conditions. We also examine the effect of silica gel p

Coexisting clathrates: Hydrate formation in ternary systems consisting of methane, water, and tetrahydrofuran (THF; 5.6 and 3.0 mol %) was monitored by measuring pressure–temperature trajectories. The hydrates formed at various points on the trajectories were identified by 13C NMR spectroscopy. In the system with a THF concentration of 3.0 mol %, the authors observed the coexistence of (pure methane) sI and (mixed methane and THF) sII hydrate structures (see graphic: water=bright, hydrate, ice,