Yu Taek 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-

In this study, the kinetics of methane replacement with carbon dioxide and nitrogen gas in methane gas hydrate prepared in porous silica gel matrices has been studied by in situ (1)H and (13)C NMR spectroscopy. The replacement process was monitored by in situ (1)H NMR spectra, where about 42 mol % of the methane in the hydrate cages was replaced in 65 h. Large amounts of free water were not observed during the replacement process, indicating a spontaneous replacement reaction upon exposing metha

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

This study investigates the hydrate inhibition performance of monoethylene glycol (MEG) with poly(vinylcaprolactam) (PVCap) for retarding the hydrate onset as well as preventing the agglomeration of hydrate particles. A high-pressure autoclave was used to determine the hydrate onset time, subcooling temperature, hydrate fraction in the liquid phase, and torque changes during hydrate formation in pure water, 0.2 wt % PVCap solution, and 20 and 30 wt % MEG solutions. In comparison to water with no

In this contribution, X-ray diffraction and 13 C NMR spectroscopy were used to identify structure and guest distribution of the mixed N 2 + CO 2 hydrates. X-ray diffraction results of the mixed N 2 + CO 2 hydrates confirmed that the unit cell parameter was ∼11.8 Å over the gas mixture composition range of 3−20 mol % CO 2 and the formed hydrates were identified as structure I. When the composition of the gas mixture was reduced to 1 mol % CO 2, the structure of the mixed hydrate was transformed t

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

The effect of the concentration of kinetic hydrate inhibitors, polyvinylpyrrolidone (PVP), and polyvinylcaprolactam (PVCap) on the onset and growth of synthetic natural gas hydrates is investigated by measuring the hydrate onset time and gas consumption rate. Although the hydrate onset time is extended by increasing the concentration from 0.5 to 3.0 wt % for both PVP and PVCap, the growth rate of hydrates shows that the different tendency depends on the type of kinetic hydrate inhibitor and its