Showing papers by "Shiro Saka published in 2006"
TL;DR: The influence of four independent process variables (temperature, time, catalyst dose, and ethanol concentration) on product yields was analyzed over a broad range using a small composite design and response surface methodology and generated regression models that describe process responses for any combination of the four variables.
Abstract: An organosolv process involving extraction with hot aqueous ethanol has been evaluated for bioconversion of hybrid poplar to ethanol. The process resulted in fractionation of poplar chips into a cellulose-rich solids fraction, an ethanol organosolv lignin (EOL) fraction, and a water-soluble fraction containing hemicellulosic sugars, sugar breakdown products, degraded lignin, and other components. The influence of four independent process variables (temperature, time, catalyst dose, and ethanol concentration) on product yields was analyzed over a broad range using a small composite design and response surface methodology. Center point conditions for the composite design (180 degrees C, 60 min, 1.25% H(2)SO(4), and 60% ethanol), yielded a solids fraction containing approximately 88% of the cellulose present in the untreated poplar. Approximately 82% of the total cellulose in the untreated poplar was recovered as monomeric glucose after hydrolysis of the solids fraction for 24 h using a low enzyme loading (20 filter paper units of cellulase/g cellulose); approximately 85% was recovered after 48 h hydrolysis. Total recovery of xylose (soluble and insoluble) was equivalent to approximately 72% of the xylose present in untreated wood. Approximately 74% of the lignin in untreated wood was recovered as EOL. Other cooking conditions resulted in either similar or inferior product yields although the distribution of components between the various fractions differed markedly. Data analysis generated regression models that describe process responses for any combination of the four variables.
478 citations
TL;DR: In this paper, the kinetics in hydrolysis and subsequent methyl esterification of fatty acids to their methyl esters in supercritical methanol were studied to elucidate reaction mechanism.
311 citations
TL;DR: In this article, a thermodynamic study was made for binary mixture of various fatty acid methyl esters to establish a prediction model for the cloud point of actual biodiesel fuel from various feedstocks.
292 citations
Abstract: The liquefaction of Japanese beech (Fagus crenata Blume) was studied with various straight-chain alcohols in subcritical and supercritical states using a batch-type reaction vessel to obtain liquid fuel from lignocellulosics. Under the reaction condition of 270°C, beech wood was liquefied to some extent in all alcohols with about 50%–65% insoluble residue left after treatment for 30min. Under the condition of 350°C, however, more than 90% of wood was decomposed and liquefied in all alcohols. Alcohols with longer alkyl chains liquefied lignocellulosics in shorter reaction times. Because many kinds of alcohols, such as methanol and ethanol, can be produced from biomass, 100% biomass-based liquid fuel can be prepared by supercritical alcohol technology when using such bioalcohols.
118 citations
Journal Article•
TL;DR: In this article, the Saka-Dadan process was proposed to convert oils/fats consisting of triglycerides and free fatty acids (FFAs) into fatty acid methyl esters through transesterification and methyl esterification, respectively, without any catalyst.
Abstract: Study presents that supercritical methanol has the ability to convert oils/fats consisting of triglycerides and free fatty acids (FFAs) into fatty acid methyl esters through transesterification and methyl esterification, respectively, without any catalyst. This one-step method (Saka process) is simpler process realizing shorter reaction time and higher yield of methyl esters than those of the conventional alkali-catalyzed method. To improve the biodiesel quality that satisfies the standard specification, another reaction route was also developed by the two-step method (Saka-Dadan process), which consists of hydrolysis step for oils/fats in subcritical water and subsequent methyl esterification of the hydrolyzed products of fatty acids from oils/fats in supercritical methanol. These new methods are highly tolerant against the presence of FFAs and water in oils/fats. Therefore, compared to the alkali-catalyzed method, proposed methods can be applied for various types of oils/fats and their wastes as raw materials to produce biodiesel fuel.
57 citations
TL;DR: In this paper, a heterogeneous mechanism for cellulose pyrolysis, starting from a molecule which is less stabilized due to lack of some intermolecular interactions, was indicated.
48 citations
TL;DR: Thermal degradation of levoglucosan (1,6-anhydro-beta-D-glucopyranose) was shown to be substantially suppressed in the presence of some aromatic compounds under the conditions of N2/240-340 degrees C/15 min.
47 citations
Journal Article•
TL;DR: In this paper, the authors consider opportunities to use tall oil distillates, obtained from kraft pulping, as a source of raw material for biodiesel fuel, or as an additive for petrodiesel.
Abstract: Effective utilization of byproducts can affect the profitability of kraft pulping to produce cellulosic fibers from wood. This review considers opportunities to use tall oil distillates, obtained from kraft pulping, as a source of raw material for biodiesel fuel, or as a source of additives for petrodiesel. Considerable progress has been achieved with respect to converting vegetable oils to diesel fuel, and some of what has been learned appears to have potential application for processing of wood-derived fatty acids and related compounds. Alkaline-catalyzed transesterification strategies, while seemingly well adapted for relatively pure vegetable oil source materials, may not be the best fit for the processing of tall oil fractions. The promising strategies to consider include acid-catalyzed esterification, enzymatic processes, hydrogenation, and the use of supercritical methanol.
43 citations
TL;DR: SC water treatment was found to be effective for enhancing the productivity of glucose from cellulose by the enzymatic hydrolysis, and alkaline treatment or wood charcoal treatment reduced inhibitory effects by various decomposed compounds of cellulose on the enzyme to achieve higher glucose yields.
Abstract: The water-soluble portion and precipitates obtained by supercritical (SC) water treatment of microcrystalline cellulose (Avicel) were enzymatically hydrolyzed. Glucose could be produced easily from both substrates, compared with the Avicel. Therefore, SC water treatment was found to be effective for enhancing the productivity of glucose from cellulose by the enzymatic hydrolysis. It is also found that alkaline treatment or wood charcoal treatment reduced inhibitory effects by various decomposed compounds of cellulose on the enzymatic hydrolysis to achieve higher glucose yields. Furthermore, glucose obtained by SC water treatment followed by the enzymatic hydrolysis of cellulose could be converted to ethanol by fermentation without any inhibition.
43 citations
TL;DR: In this article, the oxime-trimethylsilylation (TMS) method was applied to the analysis of wood pyrolysate and the results showed that glycolaldehyde decomposes into formic acid and the unknown compound with molecular weight of 72 at the injector.
25 citations
TL;DR: In this article, the supercritically treated TiO2-activated carbon composites were studied for their adsorption and subsequent photocatalytic activities for acetaldehyde, and it was found that many OH groups exist on the composites.
Abstract: The supercritically treated TiO2-activated carbon (Sc-TiO2-AC) composites were studied for their adsorption and subsequent photocatalytic activities for acetaldehyde. Sc-TiO2-AC composites showed much higher decomposing ability for acetaldehyde compared to a noncomposite comprising a simple mixture of activated carbon and TiO2. This indicates that Sc-TiO2-AC composites have a synergetic effect of adsorption and photocatalytic decomposition of acetaldehyde. Meanwhile, acetaldehyde was found to be decomposed to CO2 as final product by Sc-TiO2-AC composites through the conversion to methanol, formaldehyde and acetic acid as intermediates. It was also found that many OH groups exist on the Sc-TiO2-AC composites. These OH groups can be assumed to take part in the photocatalytic degradation of acetaldehyde.
TL;DR: In this article, supercritical fluid technology has been considered to be an environmentally-benign treatment for a conversion of woody biomass to useful fuels and chemicals in order to mitigate environmental loading.
Abstract: Owing to an environment-friendly utilization of resources, increased attention has been focused on fuels and chemicals from biomass as an alternative to fossil resources. In addition, supercritical fluid technology has been considered to be an environmentally-benign treatment. Therefore, its technology was applied for a conversion of biomass to useful fuels and chemicals in order to mitigate environmental loading. For example, supercritical water treatment has demonstrated that lignocelluloscs can be hydrolyzed to become lignin-derived products for useful aromatic chemicals and carbohydrate-derived products, such as polysaccharides, oligosaccharides and monosaccharides of glucose, mannose and xylose used for subsequent ethanol fermentation. If this treatment is prolonged, lignocellulosics were found to be converted to organic acids such as formic, acetic, glycolic and lactic acids which can be converted to methane for biofuel. When alcohols, such as methanol and ethanol, were used instead of water, some other useful products were achieved, and its liquefied products were found to have a potential for liquid biofuel. In this study, therefore, our research achievements in supercritical fluid science of woody biomass will be introduced for clean and green chemistry for a sustainable environment.
TL;DR: In this paper, supercritically treated TiO2-activated carbon (Sc-TiO2AC) composites were studied for their adsorption and photocatalytic activities toward gaseous ammonia (NH3).
Abstract: Supercritically treated TiO2-activated carbon (Sc-TiO2-AC) composites were studied for their adsorption and photocatalytic activities toward gaseous ammonia (NH3). The experiments were carried out at 26°C using a black lamp. The Sc-TiO2-AC composites attained higher photocatalytic activities than supercritically treated TiO2 (Sc-TiO2). NH3 was found out to be converted by the Sc-TiO2-AC composites to compounds such as N2, N2O, NO2−, and NO3−. The main product was harmless N2. The Sc-TiO2-AC composites are expected to be applied as effective cleaning materials to environments that emit offensive NH3 odors.
01 Jan 2006
TL;DR: In this paper, it was found that lignocellulosics could be separated into carbohydrate-derived and lignin-derived products by supercritical water treatment, and useful products such as oligosaccharides and related substances could be achieved for subsequent ethanol fermentation.
Abstract: Supercritical fluid technology has been applied to convert lignocellulosics into bioenergy and chemicals. As a result, it was found that lignocellulosics could be separated into carbohydrate-derived and lignin-derived products by supercritical water treatment. A detailed study of these products revealed that useful products such as oligosaccharides and related substances could be achieved for subsequent ethanol fermentation. It was further found that the prolonged treatment could produce various organic acids for subsequent methanogen to produce methane and methanol. Based on these lines of research achievements, supercritical water technologies were proved to be powerful to produce useful bioproducts from lignocellulosics.
Patent•
11 Oct 2006
TL;DR: In this article, a fatty acid alkyl ester can be produced by performing esterification between a fat acid and a carboxylic acid ester under predetermined temperature/pressure conditions.
Abstract: [PROBLEMS] To improve the efficiency of the production of a fatty acid alkyl ester. [MEANS FOR SOLVING PROBLEMS] A fatty acid alkyl ester can be produced by performing esterification between a fatty acid and a carboxylic acid ester under predetermined temperature/pressure conditions (step X). The fatty acid may be produced from a raw oil-and-fat material or a free fatty acid contained in the raw oil-and-fat material through a given process. The given process to be performed prior to the step X may comprises a step of performing transesterification between a fatty acid glyceride contained in the raw oil-and-fat material and a carboxylic acid under predetermined temperature/pressure conditions to yield the desired fatty acid (step A) or a step of hydrolyzing a fatty acid glyceride contained in the raw oil-and-fat material under predetermined temperature/pressure conditions to yield the desired fatty acid (step B).
Patent•
30 Jun 2006
TL;DR: In this article, the authors proposed a method of manufacturing a low-acid-number fuel for diesel engines and high-purity glycerol with an animal and/or a plant oil as raw material.
Abstract: PROBLEM TO BE SOLVED: To provide a method of manufacturing a low-acid-number fuel for diesel engines and high-purity glycerol with an animal and/or a plant oil as raw material. SOLUTION: The method comprises hydrolyzing water and an animal and/or a plant oil, adding an alcohol to the resultant fatty acids to esterify, separating and removing water and esterifying the resultant mixture again. The hydrolysis is carried out under the subcritical conditions of water, and the esterification under the supercritical conditions of the alcohol. The invention enables manufacture of a low-acid-number fuel for diesel engines and recovery of high-purity glycerol without a catalyst. COPYRIGHT: (C)2008,JPO&INPIT