Tsuyoshi Sakaki

Reaction model of cellulose decomposition in near-critical water and fermentation of products

Abstract The properties of the products obtained in the cellulose decomposition process conducted in near-critical water were analyzed using HPLC, GPC and IR. The properties of the products changed with the progress of the reaction and a reaction model consisting of the formation process of water solubles (WS) and the subsequent second decomposition process was proposed. The WS formation process is a saccharification process where hydrolysis preferentially progresses. The second decomposition process is a carbonization process of WS, where the elimination of functional groups leads to the formation of gaseous products and insolubilization of WS. The hydrolyzate solution obtained in the sacharification process could be used as a feedstock of ethanol fermentation and the fermentation rate of the solution was improved by removing furfurals with an active carbon treatment.

Lanthanum(III)-catalyzed degradation of cellulose at 250 °C

Abstract Lanthanum(III) chloride was found to effectively catalyze the degradation of cellulose in water at 250 °C. The degradation conversion of cellulose in the presence of a catalytic amount of lanthanum chloride reached 80.3% after 180 s, which corresponded to the turnover number of 83, whereas the reaction did scarcely proceed in the absence of the catalyst. The degradation products were separately quantified as water-soluble (WS), methanol-soluble (MS), methanol-insoluble (MI), and gaseous (G) products. The HPLC and GC analyses revealed that the WS materials are mainly composed of 5-hydroxymethyl-2-furaldehyde (HMF), d -glucose, and levulinic acid. Cellobiose, the disaccharide component of cellulose, was scarcely detected during the reaction.

Supercritical fluid extraction of coal under pyrolysis conditions

Abstract Supercritical fluid extraction of Wandoan coal was carried out under pyrolysis conditions using hexane, benzene, toluene and a toluene-tetralin mixture. The residues and extracts obtained were analysed using solid state 13 C nuclear magnetic resonance (n.m.r.) spectroscopy, gas chromatography (g.c.), gas chromatography-mass spectrometry (g.c.-m.s.) and gel permeation chromatography (g.p.c.), respectively, to clarify the relation among the extraction yield, the solvent power of the supercritical fluid, and the reactions taking place during extraction. The decrease in conversion, defined by 100—residue yield, at higher extraction temperatures above 653 K, was mainly due to the aromatization of coal. The aromatization was suppressed by addition of tetralin to the extraction solvent, which resulted in an increase in conversion. The extract yield was increased, without increasing the gas yield, through the enhancement of solvent power by increasing the extraction pressure or selecting the solvent. The extraction solvents used were found to be partly condensed to dimers during the extraction. The condensation of toluene was inhibited by addition of tetralin, but another dimer between tetralin and toluene was formed instead. Conversion was increased and dimer formation suppressed by impregnating tetralin into the coal in advance.

Application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to insoluble glucose oligomers in decomposed cellulose.

An analytical approach is described for the molecular weight characterization of glucose oligomers from cellulose which had been decomposed by hot-compressed water (HCW). Microcrystalline cellulose was decomposed to 18% of water insoluble fraction (WI) plus 82% of water soluble fraction (WS) by HCW (295 degrees C, 10 mL/min). The glucose oligomers in the WI were analyzed by pericullar anion exchange chromatography, and oligomers longer than pentamers were detected. These results were also confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Many peaks derived from glucose oligomers with molecular weights less than 4000 Da were detected in the spectra. Mass differences between peaks were 162 Da, as expected for polymers composed of glucose units. This appears to be the first report concerning molecular weight determination of water or organic solvent insoluble compounds like glucose oligomers from cellulose using MALDI-TOFMS.

Relationship Between Density and Swelling Ratio in a Subbituminous and a High-Volatile Bituminous Coal

The swelling ratio of Wandoan coal is related to the amount of total huminite as well as fluorescing huminite. The highest swelling ratio is observed in the 1.25-1.30 density fraction, which also has the highest content of fluorescing huminite. The Illinois No. 6 coal contains less fluorescing and more nonfluorescing vitrinite compared with Wandoan coal and shows only a general increase in its swelling ratio with increasing vitrinite content. The Illinois coal does not swell properly as a result of poor solvent penetration due to the presence of less porous, nonfluorescing telocollinite. The coal dissolves at 300°C because increased vesiculation results in an increase of external and internal dissolution relative to swelling. The study shows that the swelling ratio of coals is related to maceral composition, which in turn, is a reflection of the environment of coal formation.

Reduction in size of coal particles by heating with petroleum asphalt

Abstract The size change of coal particles by heating with petroleum asphalt from the Middle and Near East in a stream of nitrogen, was studied by measuring the particle size distributions of residual coals. From the mass balance of solvent insolubles in both heat-treated coal-asphalt slurries (Solvolysis pitches) and filtrates obtained by filtering the Solvolysis pitches at 380°C, the solvent strength of asphalt at elevated temperatures was found to be almost the same as that of benzene. Consequently, slurries heat-treated at below 400°C, at which temperature no benzene insolubles were formed from the asphalt, were extracted with benzene to recover undissolved coal particles. The particle size distributions were then measured using a photosedimentometer. The particle sizes of bituminous coals decreased with an increased conversion of coal to benzene solubles. In this paper the mechanism of reduction in particle size is discussed, and it is suggested that the disintegration of coal particles is the primary cause of the reduction in particle size of bituminous coals and that the degree of disintegration of each coal depends on the reactivity of coal with asphalt.

Separation of coal tar components by the supercritical CO2 solvent through the adsorption and structural modification

Publisher Summary This chapter discusses the novel process for the removal and recovery of quinolines and indole from methylnaphthalene oil designed by supported aluminium sulfate and the anion exchange resin, respectively, in the continuous supercritical CO 2 extraction apparatus. Supercritical fluid-mediated separation procedures is applied to capture the nitrogen compounds from coal-derived liquids and to separate the sulfur compounds from crude naphthalene through the designs of selective dimerization of benzothiophene, followed by selective extraction of purified naphthalene under supercritical CO 2 conditions. Capture and recovery of nitrogen-containing compounds from coal tar fractions are examined using a continuous supercritical CO 2 extraction apparatus with the fixed bed of a solid acid adsorbent or an ion-exchange resin. Quinoline bases and indole are separately adsorbed by Al 2 (SO4) 3 supported on silica gel and an anion exchange resin(Amberlite), and recovered by adding tetrahydrofuran (THF) and methanol, respectively, as an entrainer solvent to supercritical CO 2 through the adsorption/desorption procedure. Nitrogen compounds and purified methylnaphthalenes are alternatively recovered by the adsorption/desorption procedure.

Deashing characteristics in solvolysis coal liquefaction process

Abstract Deashing of solvolysis pitch (SP) of Miike coal was studied using settling, filtration and centrifugation. The SP obtained by the reaction below 673 K was smoothly filtered at temperatures above 623 K. Filtration was also possible at 338 K when the SP was diluted with quinoline and mixed with a small amount of fine coke powder. However, the SP obtained by the reaction above 683 K was quite different from that prepared below 673 K and was difficult to filter at elevated temperatures. It could be filtered at 338 K after dilution with quinoline. For all the samples, filtration was superior to settling and centrifugation. The optimum deashing system was proposed for each SP.

Effect of Rank and Petrographic Composition on the Swelling Behavior of Coals

The relationship between petrographic composition and swelling ratio in the 200-300°C range for five subbituminous to high-volatile bituminous coals has been investigated. The amount of fluorescing huminite / vitrinite plus the total liptinite macerals (i.e., “reactive” macerals) of the coal is the determining factor of coal swelling behavior. There is an increase in swelling ratio with increasing coal rank, as expressed by mean huminite / vitrinite reflectance. For coals of the same or very similar rank, the swelling characteristics were directly related to the amount of fluorescing huminite / vitrinite in the coal. It is also observed that the fluorescence of vitrinite in the three higher rank coals showing better swelling ratios is related to the presence of fluorophases and labile hydrogen in the vitrinite matrix. The two lower rank coals that exhibit poor swelling characteristics lack any visible fluorescence in the huminite matrix.

Estimation of the yield for coal liquid extracted by supercritical fluids

Abstract Supercritical fluid extraction of a coal liquid was carried out using benzene, toluene and p-xylene at various temperatures and pressures around the critical points of the solvents. The effects of extraction conditions on the extraction yield of coal liquid were investigated, and an empirical equation involving extraction yield as a function of reduced temperature and reduced density was obtained. The equation derived is useful in the estimation of extraction yields of coal liquids in supercritical fluid extraction processes.