Transfer hydrogenation of cellulose to sugar alcohols over supported ruthenium catalysts

Ohta

Fukuoka

2012

Catal. Sci. Technol.

Self Cite

185

120

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

mentioning

confidence: 99%

Conversion of lignocellulose into renewable chemicals by heterogeneous catalysis

Ohta

Fukuoka

2012

Catal. Sci. Technol.

Self Cite

185

120

“…It is thus indicated that Ru is oxidized to RuO 2 ·2H 2 O following H 2 reduction at 673 K and passivation in air at room temperature during synthesis of the catalyst [9]. The edge energy of Ru/BP2000 quickly shifts to 22,119 eV after 3.5 min with a simultaneous decrease of the peak at 22,147 eV and an increase of the peak at 22,165 eV.…”

Section: Resultsmentioning

confidence: 92%

“…We recently found that Ru/C catalysts promote the hydrolytic transfer hydrogenation of cellulose into sorbitol, in the presence of 2-propanol but without any added base [9], which implied that these same catalysts might accelerate both of the redox reactions in Eq. 1, via metal hydride intermediates.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous formation of sorbitol and gluconic acid from cellobiose using carbon-supported ruthenium catalysts

Komanoya

Journal of Energy Chemistry

Hara

et al. 2013

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“…We have found that a Ru/AC (AC: activated carbon, Norit SX Ultra) can convert cellulose to sugar alcohols under unusually low H2 pressure (7 atm, 1 atm 1.031325 10 5 Pa) 27) , but the successive decomposition of sugar alcohols are rather severe in this system. Thus, the yield of sugar alcohols was at most 38 % in the conversion of individually milled cellulose.…”

Section: Hydrolytic Hydrogenation Of Cellulose Bymentioning

confidence: 99%

Efficient Catalytic Conversion of Cellulose to Platform Chemicals Using Mechanical Treatment

Shrotri

Fukuoka

2015

J. Jpn. Petrol. Inst.

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Mechanical treatment of cellulose is an emerging concept for dramatically increasing the hydrolytic reactivity of cellulose. We report here the recent developments in the field of mix-milling and mechanocatalysis for cellulose pre-treatment. Mix-milling enhances the solid-solid contact between cellulose and carbon catalyst during hydrolysis reaction. Kinetic study shows that mix-milling specifically enhances the rate of cellulose to oligomer hydrolysis (13 fold), whereas the rate of oligomer to glucose hydrolysis is not influenced. Very high glucose yield of 88 % was obtained by mix-milling cellulose with K26 and using trace amount of HCl. Mix-milling was also applicable for single-pot hydrolytic hydrogenation of cellulose to sugar alcohols. Ru/AC catalyst was stable under mix-milling condition and 68 % of sugar alcohol was obtained using only 9 atm H2 pressure. Unlike mixmilling, mechanocatalysis takes advantage of presence of strong acid catalyst during milling to depolymerize cellulose. Completely soluble glucans were obtained after 7.5 h of milling in the presence of 0.25 mmol of acid g -1 cellulose. The glucans were highly reactive towards conventional and transfer hydrogenation reaction, affording ca. 90 % sugar alcohol yield in both cases after 1 h reaction. The transfer hydrogenation of cellulosic glucans was successfully upgraded to a lab-scale fixed-bed reactor.