Japan Petroleum Institute, Journal of the Japan Petroleum Institute, 1(58), p. 1-8, 2015
DOI: 10.1627/jpi.58.1
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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 mix-milling, 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.