機械的処理によるセルロースから基盤化学品への効率的な触媒分解

Abstract

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.

Kinematic Modeling of Mechanocatalytic Depolymerization of α‐Cellulose and Beechwood

“…This observation and several others of “mechanical activation” of lignocellulose for enzymatic catalysis brought about the general belief that ball milling was too energy intensive to be considered as a basic operation in biorefineries. However, in more recent years, the combination of dry milling of lignocelluloses impregnated with a strong acid has been demonstrated to dramatically enhance depolymerization rates, reducing the milling duration from 1000 h (uncatalyzed process) to less than 2 h (acid‐catalyzed process) for the full conversion of cellulose into WSPs . This approach is known as mechanocatalytic depolymerization of cellulose.…”

Kinetic Energy Dose as a Unified Metric for Comparing Ball Mills in the Mechanocatalytic Depolymerization of Lignocellulose

“…Importantly, mechanochemistry enables chemical reactivity inaccessible in solution. In this instance, solvent-free catalytic routes to depolymerize cellulose ( Hick et al, 2010 ; Meine et al, 2012 ; Hilgert et al, 2013 ; Shrotri et al, 2013 ; Zhang and Jerome, 2013 ; Käldström et al, 2014a ; Liao et al, 2014 ; Schüth et al, 2014 ; Yabushita et al, 2014 ; Dornath et al, 2015 ; Shrotri et al, 2015 ; Dong et al, 2016 ; Schneider et al, 2016 ; Yu et al, 2016 ; Schneider et al, 2017b ; Furusato et al, 2018 ; Karam et al, 2018 ; Kobayashi and Fukuoka, 2018 ), lignocellulosic biomass ( Meine et al, 2012 ; Carrasquillo-Flores et al, 2013 ; Käldström et al, 2014a ; Käldström et al, 2014b ; Schüth et al, 2014 ; Loustau-Cazalet et al, 2016 ; Schneider et al, 2017a ), and more recently, technical lignins ( Kleine et al, 2013 ; Dabral et al, 2015 ; Brittain et al, 2018 ; Dabral et al, 2018 ) constitute outstanding examples demonstrating the potential of mechanochemistry to enable chemical reactivity inaccessible in solution under ambient conditions. These routes are known as mechanocatalytic depolymerization (MCD).…”

Carbocatalysed hydrolytic cleaving of the glycosidic bond in fucoidan under microwave irradiation

“…Since the carbohydrates used in energy and chemical conversion systems are mostly polysaccharides, the release of the desired fermentable sugars involves the cleaving of the glycosidic C-O linkage along the polymer chain. A number of deconstruction methods for cellulose have been developed in order to break its structural framework, including mechanical treatment, 22 use of ionic liquids, 23 and hydrothermal liquefaction. 24,25 However, these methods are not applicable in the processing of algae because of its high moisture and oxygen content, and low bulk density.…”