We have proposed producing bioethanol from lignocellulosics using alkali pretreatment and enzymatic saccharification. In this work, a suitability of waste and recycled lignocellulosics for bioethanol production was evaluated. Sugi branches without debarking yielded a little lower glucose than that of sugi. However, it was suggested that sugi branches have sufficient potential as waste lignocellulosics for bioethanol production. Phenol resin which was included in plywood was removed effectively by alkali pretreatment, enzymatic saccharification of plywood pulp proceeded smoothly. A large amount of screen knots was produced after alkali pretreatment of particle board which contained resin. As a result, the glucose yield of particle board pulp was less than half that of sugi. A large proportion of sugi leaf was dissolved by alkali pretreatment, so the pulp yield of sugi leaf was very low. Furthermore, only a limited part of sugi leaf pulp was saccharified, and the glucose yield was only 2.8 %. These results indicated that sugi leaf is not a good lignocellulosics for bioethanol production. It was suggested that bamboo has sufficient potential as waste lignocellulosics for bioethanol production.

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Fuel ethanol production from biomass is promising technology for alleviation of global warming and reduction of fossil fuel use. In particular, production from non-food resources such as woody biomass is required. However, there are several technological problems such as development of efficient pretreatment technology, reduction of enzyme costs, and inability of conventional yeast to ferment xylose. Our research center has been conducting research to solve these problems and developed our own technology for enhancement of enzyme productivity and development of xylose-fermenting yeast strains. Our technology was effective in bench scale ethanol production experiments from eucalyptus wood using an integrated process from pretreatment to fermentation with high solid saccharification and glucose/xylose co-fermentation using a xylose-fermenting yeast strain. Our results show that ethanol production from woody biomass is feasible.

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Bioethanol is a renewable liquid fuel that has become established as a viable alternative to gasoline. Bioethanol is produced mainly in the US and Brazil from corn and sugarcane as feedstock, and world-wide production has been expanding. However, a distillation process is essential for refining bioethanol, which requires a large amount of heat, and thus offsets the carbon-neutral value. The energy efficiency of the distillation process with "Self-heat recuperation" technology was studied, which recovers sensible and latent heats by compressing the vapor from the top of the distillation column. In this study, the effect of energy saving in the distillation of bioethanol with self-heat recuperation technology was analyzed in comparison to the conventional counterpart using a temperature-heat diagram, as well as demonstrated on a pilot scale. Further demonstration tests were conducted for enzyme-recovering distillation that is used in the cellulosic ethanol production process from cellulosic biomass as feedstock to study the effect of energy saving using distillation with self-heat recuperation.

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The design and synthesis of a new linker unit to enable uniform and robust immobilization of organic functional molecules onto silica supports is described. This linker unit can prevent leaching of grafted organic functional moieties from the support. The tripodal linker unit was applied to the preparation of mesoporous silica-immobilized amino-palladium and phosphino-palladium complex catalysts for the Suzuki-Miyaura coupling reaction of aryl bromides and aryl chlorides. Catalysts including the tripodal linker displayed better catalytic activities and less palladium leaching than catalysts including a conventional trialkoxy-type linker.

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Isolated VO_x species incorporated in an SiO₂-framework were synthesized by alkoxy-exchange reactions between Si(OEt)₄, V(Ot-Bu)₃O, and polyethylene glycol (PEG). Similar alkoxy-exchange rates between alkoxides of vanadium and silicon with PEG were necessary to obtain isolated VO_x species in the SiO₂-framework. Gel was formed during the exchange reaction occurring with heating from 50 to 160 °C, liberating ethanol and t-butanol, and the obtained gel was calcined in air at 600 °C. The calcined samples were characterized by N₂ adsorption, XRD, Raman, FT-IR, H₂-TPR, and NMR techniques. Adsorption-desorption isotherms of N₂ of the obtained samples exhibited H₄-type hysteresis patterns, indicating the presence of narrow neck pores. In addition, the presence of micropores was confirmed. The samples had high surface areas of approximately 1000 m²/g, and isolated VO₄³⁻ species were present in the SiO₂-framework. Oxidative dehydrogenation of ethylbenzene was performed as a test reaction, using CO₂ as a mild oxidant. The reaction proceeded on the isolated VO₄³⁻ species in the silica framework with high ethylbenzene conversion and high selectivity for styrene.

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Ethanol produced from lignocellulosic biomass (bioethanol) is a promising alternative fuel to gasoline. Production of bioethanol from lignocellulose requires various steps, including pretreatment, enzymatic hydrolysis and fermentation. However, many fermentation inhibitors, including furfural and 5-hydroxymethyl furfural, are generated during the hydrothermal pretreatment of lignocellulose. Recent studies have identified techniques for removing fermentation inhibitors from lignocellulosic hydrolysate. The present study focused on the effect of low-concentration furfural on ethanol production by Saccharomyces cerevisiae. Specifically, gene expression of furfural-inducible genes was analyzed using a S. cerevisiae DNA microarray. The expression of most sulfur amino acid biosynthesis genes increased in response to furfural. To determine whether furfural induces the depletion of sulfur-containing amino acids, the effect of the addition of methionine on yeast growth was investigated. However, exogenous addition of methionine did not compensate for the inhibitory effect. The findings of this study show that furfural affects amino acid synthesis, even at low concentrations, and may be important in the development of high-efficiency processes for large-scale bioethanol production from lignocellulosic biomass.

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Mixed composite catalysts including three types of zeolite (Y, β and ZSM-5), kaolin and binder (Al₂O₃) were prepared as a model of an industrial catalyst for catalytic cracking and were tested in the catalytic cracking of VGO using a Curie point pyrolyzer (CPP) as a simple estimation method of catalysts for catalytic cracking. The mixed catalysts consisted of 26 wt% of zeolite, 58 wt% of kaolin and 16 wt% of a binder (Al₂O₃). The three mixed catalysts using Y (Si/Al₂=5.5), β (37), ZSM-5 (90) zeolites were named MAT(kaolin)-Y, MAT(kaolin)-β and MAT(kaolin)-Z, respectively. MAT(kaolin)-Y and MAT(kaolin)-β showed higher selectivity for gasoline and higher RON value, and produced larger amounts of olefin and multi-branched products compared with single zeolite. These results indicated that both inhibition of over-cracking and dispersion of acid sites of zeolite were important to increase RON value. The SiO₂/Al₂O₃ ratio of ZSM-5 used in this study was 90, and thus the density of acid sites of the mixed catalyst was much smaller than those for other zeolites used. Therefore, addition of kaolin to ZSM-5 significantly reduced the activity and the product selectivity. In this paper, the CPP method was found to be a simple and convenient tool to investigate the characteristics of catalysts for catalytic cracking of heavy feedstock such as VGO.

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Catalytic direct decomposition of t-butanethiol (TBT) into hydrogen sulfide over zeolites without hydrogen addition was examined as a new desulfurization process for fuel cell systems. TBT is a widely used odorant in pipeline natural gas, and was easily decomposed into hydrogen sulfide and isobutene over H-Y and H-beta at low temperatures of 25-150 °C. However, catalyst deactivation of H-beta was observed at 60 °C and oligomerized products of isobutene were observed on the catalyst surface after long reaction times. The deactivation rate of TBT decomposition over H-beta increased with higher acid amounts of H-beta. The amount of oligomerized products deposited on the catalyst increased with lower TBT conversion in the initial stage of reaction. The deposition of oligomerized products and catalyst deactivation decreased after several hours. The amount of the oligomerized products deposited on the catalyst reached approximately 6 wt% after 8 h and remained constant after 125 h over H-beta (Si/Al=92.5) at 150 °C. The initial TBT conversion was constant during 125 h.

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[in Japanese]

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We apologize for the following errors which occurred in Vol. 58, No. 2 (March issue), pages 90-95.

Label of vertical axis (Y-axis) shown in each Fig. 4 (p. 92), Fig. 5 (p. 93), Fig. 6 (p. 93), Fig. 7 (p. 94), and Fig. 8 (p. 95)
    (wrong) Adsorbance/arb. unit
    (correct) Absorbance/arb. unit

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