Masaru Hongo

Preparation of a tubular anodic aluminum oxide membrane

Abstract An anodic aluminum oxide tube with perforated straight pores to use as a porous membrane or as a support for a composite membrane was prepared. An aluminum oxide layer with straight micropores closed by an oxide barrier layer was formed on the surface of an aluminum tube, 45 mm long, 0.5 mm thick and 6 mm in outer diameter, by anodic oxidation in an aqueous solution of oxalic acid. The pores were opened by dissolution of the inner aluminum and the subsequent barrier layer of aluminum oxide. The tubular alumina membrane obtained was 35–40 μm thick with straight micropores of 20–50 nm, and therefore showed Knudsen permselectivity for inorganic gases. It was found that the tube could withstand at least up to 4.4 atm of transmembrane pressure.

Application of a membrane reactor system to thermal decomposition of CO2

Abstract An yttria stabilized zirconia (YSZ) membrane reactor system was applied to enhance the direct thermal decomposition of CO 2 at high temperature. The decomposition rate of CO 2 and the permeation rate of oxygen through the membrane were measured and their equations were established. The reaction itself and the reactions involved in the separation process were analyzed by computer simulation. It was found that the YSZ-membrane reactor system may improve the final conversion in CO 2 decomposition. The experimental results were in good agreement with the model predictions presented in this study.

Prediction of infinite dilution activity coefficients in aqueous solutions by group contribution models. A critical evaluation

Abstract Based on an extensive database, the predictive accuracy of the ASOG and several UNIFAC-type models has been critically evaluated for infinite dilution activity coefficients in aqueous solutions. In general, all the models give rather poor results with mean relative deviations of 45–72% (except the cases where the relative deviations are higher than 100%), whereas the modified UNIFAC (Dortmund) performs well for most of higher polar compounds (e.g., ethanol, acetone, acetic acid) in water mixtures. The UNIFAC–LLE of Magnussen et al. may provide order of magnitude estimates for some lower polar compounds (e.g., aldehydes or 2-ketones with carbon number of 6–9), although it gives poor results for the higher ones. In the particular case of alkanes in water mixtures, the specially developed model of Hooper et al. provides comparatively fair results, but the predicted mean relative deviations of 36% are still large. In this work, an improved UNIFAC will be proposed by using mixture-type groups to account for the specially hydrophobic effects in systems including water, satisfactory results are obtained.

Solubility and adsorption of high pressure carbon dioxide to poly(styrene)

Abstract Solubility and adsorption of high pressure carbon dioxide (CO2) to poly(styrene) (PS) were measured at 313.2 K and pressures up to 17 MPa using a quartz crystal microbalance (QCM) as a detector. Two kinds of PS film, made by dip coating (d-PS) and plasma polymerization (p-PS), were used as samples. The amount of adsorption onto both films was almost the same within the experimental range. The solubility to both films increased almost linearly against activity of CO2 up to unity, and that to p-PS was slightly higher than that to d-PS. Above unity, the solubility to p-PS film increased with the increase in activity. In contrast, solubility to d-PS sharply decreased near the unity and became a constant value.

A proposal of a new technique for the density measurement of solids

Abstract A new experimental technique for the measurement of unstable solid density that uses an oscillating U-tube was proposed. The technique was based on the simultaneous lever rules for the mass and the volume of two phase, solid+liquid (molten solid), in the U-tube. By means of this technique, the solid density can be easily determined from the overall density of solid+liquid with the combination of the literature phase diagram. To ensure the reliability, density of an amphiphilic congruent melting compound, tetrahydrofuran clathrate (THF·17H 2 O), was measured at 276.37 K under the atmospheric pressure. The density of the hydrate was estimated to be 998.40 kg/m 3 . The value was very close to the theoretical one, 999.14 kg/m 3 This technique needs a phase diagram of clathrate though it is very useful because of its simplicity and easiness to expand to a wide range of temperatures and pressures.

Bubble point pressure for binary mixtures of difluoromethane with pentafluoroethane and 1,1,1,2-tetrafluoroethane

Abstract Bubble point pressures for the two binary hydrofluorocarbon mixtures difluoromethane, CH2F2 with pentafluoroethane CHF2CF3 and 1,1,1,2-tetrafluoroethane CF3CH2F were measured using an acoustic absorption technique. Results cover the temperature range from 243 K to 333 K with an uncertainty of ±20 kPa except at 333.15 K. For the (1−x) CH2F2+xCHF2CF3 system, bubble point pressures show a maximum around x=0.2 at 248.15 K, corresponding to the azeotropic mixture. This point shifts to the CH2F2-rich region with increasing temperature, and finally vanishes out at temperatures higher than 313.15 K. Bubble pressures for the (1−x) CH2F2+xCF3CH2F system decrease monotonously with increasing composition of CF3CH2F at each temperature. These experimental data were fairly well correlated with the Peng–Robinson equation of state including the azeotropic point.

Isothermal vapor-liquid equilibria of octane with 1-butanol, 2-butanol, or 2-methyl-2-propanol

Abstract Isothermal vapor–liquid equilibria were measured for three binary systems of 1-butanol+octane at 373.15 K, 2-butanol+octane at 358.15 K, and 2-methyl-2-propanol+octane at 343.15 K. The measurements were made in a Rogalski–Malanowski type equilibrium still with circulation of both the vapor and liquid phases. Three binary isothermal systems form a maximum pressure azeotrope. The azeotropic data are x 1 (AZ)=0.519 mole fraction and P (AZ)=75.71 kPa for 1-butanol (1)+octane (2), x 1 (AZ)=0.750 mole fraction and P (AZ)=63.58 kPa for 2-butanol (1)+octane (2), and x 1 (AZ)=0.968 mole fraction and P (AZ)=61.18 kPa for 2-methyl-2-propanol (1)+octane (2). The activity coefficients of three binary systems were correlated with the Wilson, modified Wilson, nonrandom two-liquid (NRTL), and UNIQUAC equations.

Frequency change of a quartz crystal microbalance at the supercritical condition of carbon dioxide

Abstract The frequency change of a quartz crystal microbalance was examined at 40 °C and pressures up to 15 MPa with He, N2, and C02 as a pressurizing medium. The frequency largely decreased near the critical point of the C02. The change was caused by the rapid increase of the weight of C02 physically adsorbed on the evaporated silver electrodes surface.

Isothermal vapor-liquid equilibria for 2-propanol + octane and 2-propanol + 2,2,4-trimethylpentane at 348.15 K

Abstract Isothermal vapor-liquid equilibria were measured for 2-propanol + octane and 2-propanol + 2,2,4-trimethylpentane at 348.15 K. The measurements were made in a Rogalski-Malanowski-type still with circulation of both vapor and liquid phases. Both binary isothermal systems form a maximum pressure azeotrope. The azeotropic data are x1(AZ) = 0.882 mole fraction and P(AZ) = 78.20 kPa for 2-propanol (1) + octane (2) and x1(AZ) = 0.637 mole fraction and P(AZ) = 6.24 kPa for 2-propanol (1) + 2,2,4-trimethylpentane (2). The experimental data were checked for thermodynamic consistency by using three conventional tests. The activity coefficients of both systems were best correlated with the non-random two-liquid (NRTL) equation.

Vapor-liquid equilibria for binary and ternary systems composed of 2- methoxy-2-methyl propane, 2-methyl-2-propanol, and octane at 101.3 kPa

Abstract Isobaric vapor–liquid equilibria for 2-methoxy-2-methyl propane (MTBE)+2-methyl-2-propanol+octane and the constituent binary system MTBE+2-methyl-2-propanol have been measured at 101.3 kPa. The measurements were made in an equilibrium still with circulation of both the vapor and liquid phases. The ternary system of MTBE+2-methyl-2-propanol+octane and the binary system of MTBE+2-methyl-2-propanol are both non-azeotropic. The constituent binary systems of 2-methyl-2-propanol+octane and MTBE+octane, which were measured in our previous work [T. Hiaki, A. Taniguchi, T. Tsuji, M. Hongo, K. Kojima, J. Chem. Eng. Data, 41 (1996) 1087–1090; T. Hiaki, K. Tatsuhana, T. Tsuji, M. Hongo, J. Chem. Eng. Data (1998), in press] are also non-azeotropes. The experimental data of the binary systems were correlated with the non-random two-liquid (NRTL) equation. The NRTL equation yielded a good prediction of activity coefficients for the ternary system from the parameters of the correlated binary systems.