Toshitaka Funazukuri

Polysaccharide Hydrolysis Accelerated by Adding Carbon Dioxide under Hydrothermal Conditions

Polysaccharides such as agar, guar gum, starch, and xylan were hydrolyzed to produce mono‐ and oligosaccharides under hydrothermal conditions with and without carbon dioxide in a small batch reactor. The molecular weight distributions of the polysaccharide hydrolyzates shifted to lower molecular weights by increasing the carbon dioxide load, corresponding to higher pressures of carbon dioxide. For example, the yield of glucose produced from the hydrolysis of starch at 200 °C was increased significantly from 3.7% to 53.0% (on a carbon weight basis) of the initial polysaccharide by increasing carbon dioxide load in a reaction time of 15 min. Carbonic acid generated from water and carbon dioxide appeared to lower the pH of high‐temperature and high‐pressure water. Polysaccharide hydrolysis under hydrothermal conditions in the presence of carbon dioxide is an environmentally benign method to produce mono‐ and oligosaccharides because the process does not require the use of conventional acids and bases followed by neutralization and separation.

Binary diffusion coefficients, partition ratios and partial molar volumes at infinite dilution for β-carotene and α-tocopherol in supercritical carbon dioxide

Abstract Binary diffusion coefficients D 12 and partition ratios k at infinite dilution for β-carotene and α-tocopherol in supercritical carbon dioxide were measured at temperatures from 308.15 to 333.15 K and pressures from 9 to 30 MPa by a tracer response technique with a poly(ethylene glycol) coated capillary column. Both parameters, simultaneously determined by fitting the calculated response curve to that measured experimentally, were well represented with the correlations: the D 12 / T values were correlated with CO 2 viscosity, and the k values were expressed with a function of temperature and CO 2 density. However, the partial molar volumes obtained from the k values were not well consistent with those estimated using equation of states having the interaction parameters k ij reported in the literature.

Infinite-Dilution Binary Diffusion Coefficients of 2-Propanone, 2-Butanone, 2-Pentanone, and 3-Pentanone in CO2 by the Taylor Dispersion Technique from 308.15 to 328.15 K in the Pressure Range from 8 to 35 MPa

Infinite-dilution binary diffusion coefficients of 2-propanone, 2-butanone, 2-pentanone, and 3-pentanone in carbon dioxide were measured by the Taylor dispersion method at temperatures from 308.15 to 328.15 K and pressures from 7.60 to 34.57 MPa. The D12 values were obtained from the response curves by the method of fitting in the time domain. The accuracy in the fitting error was examined for each measurement. The measured D12 data were found to be well correlated by the Schmidt number correlation, with AAD%=3.74% for all solutes.

Infinite Dilution Binary Diffusion Coefficients of Benzene in Carbon Dioxide by the Taylor Dispersion Technique at Temperatures from 308.15 to 328.15 K and Pressures from 6 to 30 MPa

Infinite dilution binary diffusion coefficients, D12, of benzene in carbon dioxide were measured by the Taylor dispersion technique at temperatures from 308.15 to 328.15 K and pressures from 6 to 30 MPa. The diffusion coefficients were obtained by the method of fitting in the time domain from the response curves measured with a UV–vis multidetector by scanning from 220 to 280 nm at increments of 1 or 4 nm. The wavelength dependences on the binary diffusion coefficient and the uncertainty were examined. The detector linearity, in terms of the relationship between the absorbance intensity and the product of the peak area of the response curve and CO2 velocity, was found to fail at some characteristic absorption wavelengths such as 243, 248, 253, and 259 nm, even when the maximum absorbance intensities of the response curves were less than 0.5 and the fits were good. Although the D12 values obtained from the response curves measured at 253 nm were almost consistent with some literature data, the D12 values measured at wavelengths showing the detector linearity to be satisfactory, i.e., at 239 nm, were higher than those at 253 nm. The present D12 data at 239 nm were well represented by the Schmidt number correlation, except for those showing the anomalous decrease in a plot of D12 vs density in the density range from 250 to 500 kg·m−3.

Liquefaction of lignin sulphonate with subcritical and supercritical water

Abstract Liquefaction of lignin sulphonate samples was carried out with subcritical and supercritical water in a batch tube-type bomb reactor. Samples were also subjected to pyrolysis in an argon atmosphere. At 673 K, much higher oil yields were obtained with supercritical water than with pyrolysis. Oil yield was affected by reaction temperature, time, and water density. 1 H-n.m.r. spectra showed that oils obtained at short reaction times had relatively high methoxyl hydrogen contents.

Diffusion coefficients of linoleic acid methyl ester, Vitamin K3 and indole in mixtures of carbon dioxide and n-hexane at 313.2 K, and 16.0 MPa and 25.0 MPa

Abstract Diffusion coefficients of linoleic acid methyl ester, Vitamin K3 and indole in mixtures of carbon dioxide and n-hexane were measured at 313.2 K, and 16.0 and 25.0 MPa by using the Taylor dispersion method. It was found that the measured diffusion coefficients D1m were well correlated by the Blancs equation: D 1m = 1 x 2 /D 12 +x 3 /D 13 where x2 and x3 are mole fractions of CO2 and n-hexane, and D12 and D13 are binary diffusion coefficients of the solutes in CO2 and n-hexane, respectively, measured at the same temperature and pressure. Other equations for D1m, as a function of temperature and solvent viscosity, were tested as a possible correlating equation.

Tracer diffusion coefficients of benzene in dense CO2 at 313.2 K and 8.5–30 MPa

Abstract Binary diffusion coefficients D12 of benzene at infinite dilution in carbon dioxide were measured at 313.2 K in the pressure range from 8.5 to 30 MPa by the Taylor dispersion method. At 313.2 K, the measured values in this study were slightly higher than those of Swaid and Schneider, 1979, and lower than those of Sassiat et al., 1987. It was found that the D12 values measured with the coiled diffusion column installed vertically were lower than those when it was installed horizontally. The correlation of D12 with solvent viscosity was effective for the D12 of benzene, both in dense CO2 and in the liquid solvents: hexane, cyclohexane and dodecane. In addition, the measured D12 decreased smoothly with increasing pressure, and there was no evidence of the anomalous decrease in D12 at 313.2 K in the pressure range from 8.5 to 30 MPa.

Product distribution for flash pyrolysis of cellulose in a coil pyrolyzer

Abstract Objectives of this study were to (1) examine the performance of a commercial coil pyrolyzer as a flash pyrolysis instrument, (2) determine product distribution from cellulose under flash pyrolysis conditions, and (3) investigate the effect of cellulose type, particle size, heating rate, heating time, and final or soaking temperature on the distribution. It was found that the pyrolysis behavior of the products could be classified into two groups according to their similarity with the production of CO or CO2. In the former, yield was an exponential function of weight loss, whereas in the latter, yield was an arithmetic function of weight loss. In the range studied, particle size and heating rate did not influence yield or its weight loss behavior. The type of cellulose, mainly degree of polymerization, influenced yield but not behavior.

Product distribution in pyrolysis of cellulose in a microfluidized bed

Abstract A study of flash pyrolysis of cellulose was carried out in the temperature range from 313 to 770°C in a microfluidized bed. Chemical analysis was done for gaseous and liquid products using gas chromatography. Levoglucosan was measured after silylation of the tar fraction. In the fluidized bed, residence times were of the order of 1 s, while heating rates were estimated at higher than 100,000°C/s for cellulose particles of 60 μm diameter and about 1000°C/s for cellulose particles having about 0.6 mm mean particle diameter. No pronounced effects of particle size were observed. Logarithms of product yields as wt.% of sample correlate linearly with bed temperature. Transitions in these curves are observed between 500 and 600°C corresponding roughly to decomposition of levoglucosan. Effects of atmosphere were also studied by comparing the effect of various atmospheres (CO, CO 2 , H 2 + N 2 ) with pure N 2 . Only a slight effect was noted on the product distribution. It appears that levoglucosan, a major product obtained from the slow pyrolysis of cellulose, is not a primary product under flash pyrolysis conditions.

Oil extraction from Australian Condor oil shale with water and CO in the presence of Na2CO3

Abstract Extraction of oil from Australian Condor oil shale was carried out in a batch autoclave, heated at a rate of 8.5 K min−1 from room temperature to 673 K and maintained at this temperature for 1 h, in either a water + argon, water + CO or water + CO + Na2CO3 atmosphere. Solvent effect for the extraction decreased in the order water + CO + Na2CO3 to water + CO to water + argon. The oil yield was slightly higher with water + CO than with water + CO + Na2CO3 at a water density of 200 kg m−3. The maximum oil yield (46 wt% daf) was obtained under the conditions of water density of 200 kg m −3 (at 673 K) and 1 MPa partial-pressure of CO, when it was charged to the autoclave at room temperature. This oil yield was higher than that (33wt% daf) of the Fischer assay. It was found from 1H n.m.r. spectra and g.p.c. scans of the oil that the decomposition of kerogen was promoted by CO, and the presence of Na2CO3 suppressed decomposition of the extracted oil into lighter species.