No abstract

High-yielding one-pot synthesis of glucose from cellulose and pentoses/hexoses from real biomass is achieved by using simple activated carbons and 0.012% HCl in water. Ball-milling cellulose and the carbon together created good physical contact between the solid substrate and solid catalyst before the reaction, selectively and drastically improving the depolymerization rate of cellulose to oligomers. Thus, our methodology overcomes a major obstacle in this type of reaction, namely, that the collision between a solid catalyst and a solid substrate is limited. Mechanistic studies have suggested that the active sites of the carbons are weakly acidic functional groups, in which vicinal carboxylic and phenolic groups synergistically work for the hydrolysis reaction.

Cellulose is converted into sorbitol and related sugar compounds over water-tolerant and durable carbon-supported Pt catalysts under aqueous hydrogenation conditions. Pre-treatment of cellulose with ball-milling effectively reduces the crystallinity and particle size of cellulose, which results in 10 high conversion of cellulose to sorbitol and mannitol. The selectivity of sorbitol increases by using Cl-free metal precursors in the catalyst preparation as residual Cl on the catalysts promotes the side-reactions. The transformation of cellulose to sorbitol consists of the hydrolysis of cellulose to glucose via water-soluble oligosaccharides and the successive hydrogenation of glucose to sorbitol. The hydrolysis of cellulose is the rate-determining step, and the Pt catalysts promote both the 15 hydrolysis and the hydrogenation steps.

This paper describes the microstructure to improve the magnetic field dependence of the critical current density, Jc, of Y(RE)Ba2Cu3O7−x [Y(RE)123, RE: Gd and Sm] coated conductors. A columnar microstructure 10nm in diameter has been obtained by using Y123 targets including yttrium-stabilized zirconium for the pulsed-laser deposition. This columnar structure, composed of BaZrO3 and Y123, continued from the substrate to the surface of the film 0.25μm in thickness. We have named it “the bamboo structure” from its morphology. The bamboo structure was effective for increasing Jc in a magnetic field especially parallel to the c-axis. We have also found stacking faults in RE123 effective to improve Jc.

Conversion of biomass to renewable and valuable chemicals has attracted global interest in order to build up sustainable societies. Cellulose is the most abundant and non-food biomass; however, the low reactivity of cellulose has prevented its use in chemical industry except for the paper manufacturing. The heterogeneous catalysis for the conversion of cellulose has been expected to overcome this issue, because various types of heterogeneous catalysts can be designed and applied in a wide range of reaction conditions. Furthermore, solid catalysts are easily recovered and reused. In this review article, we show the present situation and perspective of heterogeneous catalysis for the transformation of cellulose into useful platform 2 chemicals.

No abstract

Conversion of lignocellulose into renewable chemicals and fuels has received great attention for building up the sustainable societies. However, the utilisation of lignocellulose in the chemical industry has almost been limited for paper manufacturing because of the complicated chemical structure and persistent property of lignocellulose. Heterogeneous catalysis has the potential to selectively convert lignocellulosic biomasses into various useful chemicals, and this methodology has rapidly progressed in the last several 10 years. In this perspective article, we outline our recent approaches on the heterogeneous catalysis for this challenging subject with related literatures. Lignocellulose as a renewable resourceConversion of biomass to renewable fuels and chemicals has attracted significant attention as a key technology for the 15 sustainable societies.1 Lignocellulose is the most abundant biomass resource, produced together with sugars and starch from carbon dioxide and water via the photosynthesis using sunlight and successive metabolism in plants. Lignocellulose is not digestible for human beings, which is an advantage over sugars 20 and starch since the use of edible carbohydrates for the synthesis of bioethanol fuel has competed with the food production, giving us a consensus that we should use non-food biomass as a feedstock to fuels and chemicals. Therefore, lignocellulose is one of the most attractive biomass resources in nature. 25Lignocellulose in woods consists of cellulose (40-50%), hemicellulose (20-40%) and lignin (20-30%).2 Cellulose is a water-insoluble polymer composed of glucose linked by -1,4-glycosidic bonds ( Fig. 1(a)) and forms robust crystal structures with inter-and intra-molecular hydrogen bonds, possessing high 30 chemical stability. 3 Hemicellulose is also a polysaccharide, but

Ru/C catalysts are active for the conversion of cellulose using 2-propanol or H2 of 0.8 MPa as sources of hydrogen, whereas Ru/Al2O3 catalyst is inactive in both reactions, indicating that the Ru/C catalysts are remarkably effective for the cellulose conversion