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 ha...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 lignocellulosics 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.展开更多
In the present work,the combined effects of temperature and reaction time on hydrolysis of Japanese beech as treated by batch hot-compressed water were investigated by response surface methodology.A two-factor and thr...In the present work,the combined effects of temperature and reaction time on hydrolysis of Japanese beech as treated by batch hot-compressed water were investigated by response surface methodology.A two-factor and three-level full factorial design was used for experimental design.The statistical models were established to configure the relationship between process conditions(temperature and reaction time)and water-soluble,saccharides from hemicelluloses(including arabinose,galactose,mannose,rhamnose,xylose and xylooligosaccharides)as well as decomposition compounds(5-HMF,furfural and organic acids).As a result of multiple response numerical optimization by applying desirability function method,the optimal hydrolysis conditions were obtained to be temperature of 200℃and reaction time of 3 min.At this optimum point,water-soluble,saccharides from hemicelluloses,5-HMF,furfural and organic acids were 31.5%,19.5%,0.28%,0.70%,and 0.59%,respectively.展开更多
Microcrystalline cellulose (avicel) is treated in hot-compressed aprotic solvents, sulfolane and 1,4-dioxane, using a batch-type reaction system with a molten tin bath in a range from 290 to 390°C. The correspond...Microcrystalline cellulose (avicel) is treated in hot-compressed aprotic solvents, sulfolane and 1,4-dioxane, using a batch-type reaction system with a molten tin bath in a range from 290 to 390°C. The corresponding densities of the solvent are 0.25–1.26 g/cm3 and 0.21–1.03 g/cm3 for sulfolane and 1,4-dioxane, respectively. As a result, in both solvents, more than 90% of cellulose is found to be decomposed to the solvent-soluble portion in which levoglucosan is the main component with the highest yield of about 35% on original cellulose basis. The decomposition rate to levoglucosan is, however, faster in sulfolane than in 1,4-dioxane, while levoglucosan is more stable in 1,4-dioxane. In addition, its yield is found to be solvent-density dependent to be highest around 0.4–0.5 g/cm3 for both solvents. To elucidate these decomposition behaviors, the results obtained in this study with aprotic solvents are compared with protic solvents such as water and methanol in previous works.展开更多
文摘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 lignocellulosics 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.
文摘In the present work,the combined effects of temperature and reaction time on hydrolysis of Japanese beech as treated by batch hot-compressed water were investigated by response surface methodology.A two-factor and three-level full factorial design was used for experimental design.The statistical models were established to configure the relationship between process conditions(temperature and reaction time)and water-soluble,saccharides from hemicelluloses(including arabinose,galactose,mannose,rhamnose,xylose and xylooligosaccharides)as well as decomposition compounds(5-HMF,furfural and organic acids).As a result of multiple response numerical optimization by applying desirability function method,the optimal hydrolysis conditions were obtained to be temperature of 200℃and reaction time of 3 min.At this optimum point,water-soluble,saccharides from hemicelluloses,5-HMF,furfural and organic acids were 31.5%,19.5%,0.28%,0.70%,and 0.59%,respectively.
基金the National Natural Science Foundation of China (Grant No. 90610035)
文摘Microcrystalline cellulose (avicel) is treated in hot-compressed aprotic solvents, sulfolane and 1,4-dioxane, using a batch-type reaction system with a molten tin bath in a range from 290 to 390°C. The corresponding densities of the solvent are 0.25–1.26 g/cm3 and 0.21–1.03 g/cm3 for sulfolane and 1,4-dioxane, respectively. As a result, in both solvents, more than 90% of cellulose is found to be decomposed to the solvent-soluble portion in which levoglucosan is the main component with the highest yield of about 35% on original cellulose basis. The decomposition rate to levoglucosan is, however, faster in sulfolane than in 1,4-dioxane, while levoglucosan is more stable in 1,4-dioxane. In addition, its yield is found to be solvent-density dependent to be highest around 0.4–0.5 g/cm3 for both solvents. To elucidate these decomposition behaviors, the results obtained in this study with aprotic solvents are compared with protic solvents such as water and methanol in previous works.
