Microscopic Investigations on Woody Biomass as Treated with Ionic Liquids

Woody biomass is one of the most promising renewable alternatives to fossil resources. However, some physical and chemical treatment is required to convert their chemical components into biofuels and valuable chemicals because of their low degradative properties. Recently, there has been considerable interest in ionic liquid treatment for biorefinery, and many fundamental studies on the reactivity of wood with ionic liquids have been performed from a chemical and morphological point of view. This chapter highlights the findings regarding morphological and topochemical features of wood cell walls in the degradation process as a result of ionic liquid treatment. Bright-field microscopy and scanning electron microscopy have revealed the swelling behavior of cell walls and the detailed ultrastructural features of wood tissues treated with ionic liquid. Polarized light microscopy and confocal Raman microscopy have clarified the changes in cellulose crystallinity and distribution of chemical compositions such as polysaccharides and lignin during ionic liquid treatment at the cellular level

Depolymerization of Native Lignin into Vanillin, Vanillic Acid, and Other Related Compounds via Alkaline Aerobic Oxidation: Reaction Mechanisms and Process Control Using Organic Cations

Vanillin is one of the platform chemicals in industry, which is used not only as a traditional fragrance but also as a raw material for medicines and polymer materials. Industrial vanillin production by alkaline aerobic oxidation of lignin is carried out with degradation of lignosulfonate at temperatures around 170°C under pressurized air in the presence of Cu2+ as a catalyst. However, this method has problems such as low vanillin yields and by production of sulfur-containing wastewater, and various studies have been conducted to solve them. Research on the mechanism of the vanillin formation reaction by aerobic oxidation of lignin and the search for a method to control this reaction has also been conducted. In this chapter, we review relevant studies from the above perspective, mainly those conducted by the authors’ research group

Direct Extraction of Polysaccharides from Moso Bamboo (Phylostachys heterocycla) Chips Using a Mixed Solvent System of an Amino Acid Ionic Liquid with Polar Aprotic Solvent

The cellulose-dissolving ability and some physical properties of mixed solvents of an amino acid IL, N-methyl-N-(2-methoxyethyl)pyrolidin-1-ium 2,6-diaminohexanoate ([P1ME][Lys]), with polar aprotic solvents, such as 1,3-dimethylimidazolidinone (DMI), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), and acetonitrile (CH3CN), have been investigated. The viscosity was significantly reduced by the increasing content of polar aprotic solvents, and a 1:1 mixture (molar ratio) of [P1ME][Lys] with DMF showed 91.5 cP which corresponded to less than 1/10 compared to that of the pure IL at 25 °C (1058 cP). The β values of the mixed solvents, which have the IL contents over 0.1, exhibited β-values similar to that of the pure IL. On the other hand, the π-value was dependent on the ratio of the IL content, and the pure IL had the highest π-value. We found that the mixed solvent of [P1ME][Lys] with DMF (1:1) easily dissolved the cellulose and the mixed solvent could be used to extract cellulose from moso bamboo (Phylostachys heterocycla) powder. The efficiency of the extraction of cellulose from the bamboo powder was significantly increased when a 1:1 mixture of the IL with a polar aprotic solvent was used as the extracting solvent at 60 °C; the extraction ratio of the 1:1 mixture (IL: DMF) reached twice that of the pure IL. We thus obtained cellulose in 18% (w/w) yield from the bamboo powder

ゾル - ゲルホウ ニ ヨル ナンネンセイ ムキシツ フクゴウカ モクザイ ノ ソウセイ

京都大学0048新制・論文博士博士(エネルギー科学)乙第10562号論エネ博第16号新制||エネ||8(附属図書館)UT51-2000-R84(主査)教授 坂 志朗, 教授 新宮 秀夫, 教授 笠原 三紀夫学位規則第4条第2項該当Doctor of Energy ScienceKyoto UniversityDFA

Methane production from organic acids obtained by supercritical water treatment of Japanese beech

Japanese beech (Fagus crenata) wood was treated in supercritical water at 380°C/30 MPa and 380°C/100 MPa. The hydrolysate (water-soluble portion) was found to contain the fragmented and dehydrated compounds of sugars and organic acids. Although organic acids are expected to be utilized for methane fermentation, the effects of the fragmented and dehydrated compounds of sugars on methane production are not known. The objective of this study is, therefore, to elucidate the potential of supercritical water treatment as a new pretreatment for methane production by evaluating the methane fermentability of the hydrolysate. From the methane fermentation tests for those model compounds with digested sludge, it is found that methane was produced not from the fragmented and dehydrated compounds but from the organic acids. The yield of methane from the hydrolysate obtained at 380°C/30 MPa was higher than that from the hydrolysate obtained at 380°C/100 MPa because the former contains more organic acids than the latter. The maximum yield of methane was seven times greater compared to the untreated wood, indicating that the supercritical water treatment is effective for enhancing the productivity of methane from wood

Ethanol production with β-xylosidase, xylose isomerase, and Saccharomyces cerevisiae from the hydrolysate of Japanese beech after hot-compressed water treatment

Ethanol was produced from the hydrolysate collected as the water-soluble (WS) portion after hot-compressed water (HCW) treatment of Japanese beech. The process involved saccharification with β-xylosidase followed by isomerization with xylose isomerase and fermentation with Saccharomyces cerevisiae. Several process schemes were compared to investigate the effect of process integration of saccharification, isomerization, and fermentation. Higher ethanol yields were obtained for the processes that integrated isomerization and fermentation or saccharification and isomerization. Integration of isomerization and fermentation was effective in converting xylose into ethanol. Similarly, integration of saccharification and isomerization was effective in converting xylooligosaccharides into xylulose. It is presumed that the saccharification reaction toward xylose and the isomerization reaction toward xylulose were linked and therefore each reaction was enhanced

Process integration of ethanol production from Japanese beech as treated with hot-compressed water followed by enzymatic treatment

Ethanol was produced from the hydrolysate collected as a water-soluble (WS) portion and a residue after hot-compressed water (HCW) treatment of Japanese beech with and without fractionation. Simultaneous saccharifi cation with β-xylosidase and isomerization with xylose isomerase followed by fermentation with Saccharomyces cerevisiae were applied to the WS portion; simultaneous saccharifi cation with cellulase and fermentation with S. cerevisiae was applied to the residue. Integration of the processes for the WS portion and the residue was investigated to improve the conversion effi ciency throughout the whole process. The ethanol yield in the integrated process without fractionation was comparable with that for the process with fractionation. Ethanol yields were improved for both of the processes by modifying the operation pattern in which cellulase was added prior to fermentation of the residue