Takashi Katayama

Isothermal vapor-liquid equilibrium data for the ethane—carbon dioxide system at high pressures

Abstract Isothermal vapor-liquid equilibrium data for the ethane—carbon dioxide system at high pressures were obtained at 10, 15, 18, 20, and 25°C. The gas-liquid critical data (pressure—temperature—composition) for the system were also measured at several temperatures, and the azeotropic points were obtained at 10, 15, and 18°C. This system exhibits two critical points and one azeotropic point in the temperature range from 17.5°C to 18.5°C.

Solubilities of naphthalene and indole in supercritical fluids

Abstract Solubilities of naphthalene and indole in carbon dioxide, ethylene, and ethane were measured at 308.15 K over a pressure range of 5 to 20 MPa. The solubility data were obtained, using a newly developed static method that utilizes supercritical fluid chromatography. The data obtained are well correlated by applying the Soave-Redlich-Kwong equation of state to the fugacity coefficient of the fluid phase. In addition, the relation between the solubility and the fluid phase density is briefly discussed for each binary system by use of the virial equation of state.

Whisker formation from jet of supercritical fluid solution

Abstract The growth mechanism of a whisker of stigmasterol particles deposited by rapid expansion from supercritical CO 2 solutions has been investigated by scanning electron microscope. Amorphous fine particles were found to be under relatively low pre-expansion pressures while whisker-like crystals were observed under relatively high pre-expansion pressures. The turning point was about 13 MPa at 373 K. It was found that the secondary products grew on a screen in the expansion jet after deposition of primary particles of about 10-nm diameter. The morphology of secondary products was found to strongly depend on the surface condition of the primary particle. Because of the temperature decrease caused by the rapid expansion, the pre-expansion pressure plays an important role in determining the thermal roughening degree on the surface of primary particles, and consequently the morphology of the secondary products.

Pressure-density-temperature (p-p-T) relations of CHF3, N2O, and C3H6 in the critical region

Abstract The pressure-density-temperature (p-ϱ-T) relations in the critical region (0.996

Isothermal vapor-liquid equilibria for the binary systems propylene-carbon dioxide, propylene-ethylene and propylene-ethane at high pressure

Abstract isothermal vapor-liquid equilibria for the binary systems propylene-carbon dioxide, propylene-ethylene and propylene-ethane have been measured at 283.15 and 298.15 K using a static method. The equilibrium data obtained have been correlated with the total-pressure method using both the Redlich-Kwong equation of state modified by Soave and the perturbation equation proposed by Gubbins and Twu. From normal probability plots of the residuals in the correlations versus the theoretical residuals in the normal distribution, the applicability of each of these two equations has been tested statistically. Furthermore, the fugacity coefficients calculated from the virial equation have been compared with those obtained from the correlations for the low-pressure regions.

Phase equilibria for four binary systems containing propylene

Isothermal vapor—liquid equilibria (P−x, y) for four binary systems of propylene with methanol, acetone, diethyl ether and propylene oxide were measured using a swing method at 25°C. Also, the saturated molar volume of the liquid phase for each system was obtained by a weighing method. The data obtained were correlated by use of the Soave-Redlich-Wong equation. The P-x, y relations were described satisfactorily, except for the methanol—propylene

Isothermal vapor—liquid equilibria for two binary mixtures of heptane with 2-butanone and 4-4-methyl-2-pentanone measured by a dynamic still with a pressure regulation

Abstract Isothermal vapor—liquid equilibrium data are presented for two binary mixtures of heptane with 2-butanone at 45°C and 4-methyl-2-pentanone at 70°C. A control system is connected to a vapor and liquid recirculating still; the recorded fluctuations of still temperature usually have been within ±0.005 K. The data points are consistent according to the local area test. The experimental activity coefficients are compared with those predicted by the UNIFAC method.

Solubilities of indole, skatole, and 5-Methoxyindole in supercritical fluids

Abstract Solubilities of skatole and 5-methoxyindole in supercritical carbon dioxide, ethylene, ethane, and trifluoromethane were measured at 308.15 K by means of a static method utilizing supercritical fluid chromatography. Solubility data for the indole-trifluoromethane system were also obtained in the same manner. The solubilities of solid components in all the supercritical fluids examined varied greatly with the presence of a substituent. It is found that the large dipole moment of trifluoromethane (1.65 D) plays an important role in enhancing the solubility of each solid component investigated.

Solubilities of Indole Derivatives in Supercritical fluids

Abstract Solid solubilities of five indole derivatives (5-aminoindole, oxindole, 5-hydroxyindole, andole-3-aldehyde, and indole-3-carboxylic. acid) in supercritical carbon dioxide, ethylene, ethane, and trifluoromethane were measured at 308.15 K using a static method coupled with on-line SFC analysis. A range of solid solubilities that depend on the nature of the substituent is observed. The order of the solubilities of individual solids in each supercritical fluid is found to be the same for all the fluids. Also, the solubilities of these indole derivatives seem to be grouped into two types according to the sign of the Hammett constant of the substituent involved. The degree of solubility is associated with the value of the Hammett constant which represents the π-electron density.

Phase behavior of binary mixtures of indole or quinoxaline with CO2, C2H4, C2H6, and CHF3 in the critical region

Abstract Phase behavior of eight binary mixtures consisting of indole or quinoxaline as the first component and CO 2 , C 2 H 4 , C 2 H 6 , or CHF 3 as the second component was investigated around the critical point of the light component in the temperature range from 280 to 350 K and pressures up to 30 MPa. These systems show three kinds of phase diagrams. The observed phase boundaries correspond to the three-phase coexisting lines (i.e., liquid-liquid-gas, solid-liquid-liquid, and solid-liquid-gas) and the critical lines (i.e., liquid=liquid and liquid=gas). Some nonvariant points for binary mixtures are also obtained. These include a quadruple point where four phases (solid-liquid-liquid-gas) coexist in equilibrium, and critical end points where two fluid phases are critically identical in the presence of another phase.