Direct Microwave-Assisted Hydrothermal Depolymerization of Cellulose

Fan, Jiajun; bruyn, Mario De; Budarin, Vitaliy L.; Gronnow, Mark; Shuttleworth, Peter S.; Breeden, Simon W.; Macquarrie, Duncan J.; Clark, James H.

doi:10.1021/ja4056273

Cited by 208 publications

(150 citation statements)

References 48 publications

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“…Its conformation and dynamics affects hydrogen bond pattern in crystals and solution, 1,2,3 reactivity, 4,5,6 and aqueous solubility. 7,8 The three-dimensional structure of carbohydrates is also a key feature for biological carbohydrate recognition.…”

Section: Introductionmentioning

confidence: 99%

Temperature Dependence of Hydroxymethyl Group Rotamer Populations in Cellooligomers

et al. 2015

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Empirical force fields for computer simulations of carbohydrates are often implicitly assumed to be valid also at temperatures different from room temperature for which they were optimized. Herein, the temperature dependence of the hydroxymethyl group rotamer populations in short oligosaccharides is investigated using molecular dynamics simulations and NMR spectroscopy. Two oligosaccharides, viz., methyl β-cellobioside and β-cellotetraose were simulated using three different carbohydrate force fields (CHARMM C35, GLYCAM06 and GROMOS 56A carbo ) in combination with different water models (SPC, SPC/E and TIP3P) using replica exchange molecular dynamics simulations. For comparison, hydroxymethyl group rotamer populations were investigated for methyl β-cellobioside and cellopentaose based on measured NMR 3 J H5,H6 coupling constants, in the latter case by using a chemical shift selective NMR-filter.Molecular dynamics simulations in combination with NMR spectroscopy show that the temperature dependence of the hydroxymethyl rotamer population in these short cellooligomers, in the range 263 K to 344 K, generally becomes exaggerated in simulations when compared to experimental 2 data, but also that it is dependent on simulation conditions, and most notably properties of the water model.

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Section: Introductionmentioning

confidence: 99%

Temperature Dependence of Hydroxymethyl Group Rotamer Populations in Cellooligomers

et al. 2015

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“…With the Pyrex glass reactor, the extent of acid hydrolysis of cellulose to glucose was 56% upon microwave heating at 200 • C, nearly identical with the yield (55%) in the SiC reactor. Related to this, Fan and coworkers [17] inferred that the enhanced rate of hydrolysis of cellulose is likely due to a notable interaction of microwaves with the biomass, and further demonstrated that the selectivity and yield of glucose depend on the microwave power density and distribution; the latter demonstration was outside the scope of the present study. Their study showed no significant features in biomass conversion even when the catalyst was selectively heated by the microwaves.…”

Section: Acid Hydrolysis Of Cellulose In the Presence Of Ac-so 3 Hmentioning

confidence: 63%

Is Selective Heating of the Sulfonic Acid Catalyst AC-SO3H by Microwave Radiation Crucial in the Acid Hydrolysis of Cellulose to Glucose in Aqueous Media?

et al. 2017

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Selective heating of microwave-absorbing solid catalysts in a heterogeneous medium may affect a chemical reaction; such selectivity cannot be achieved by conventional oil-bath or steam heating methods. Moreover, microwave methods are often misunderstood with respect to equipment and temperature measurements, so that additional experimentation is necessary. In this regard, the present study intended to clarify the effect of microwave selective heating on acid hydrolytic processes using a sulfonated activated carbon catalyst (AC-SO 3 H). The model reaction chosen was the acid hydrolysis of cellulose carried out in a Pyrex glass microwave reactor, with the process being monitored by examining the quantity of total sugar, reducing sugar, and glucose produced. Heat transfer from the catalyst to the aqueous solution through absorption of microwaves by the catalyst occurred as predicted from a simulation of heat transfer processes. The resulting experimental consequences are compared with those from the more uniform microwave conduction heating method by also performing the reaction in a SiC microwave reactor wherein microwaves are absorbed by SiC. Some inferences of the influence of microwave selective heating of carbon-based catalyst particles are reported. Under selective heating conditions (Pyrex glass reactor), the yield of glucose from the acid hydrolysis of cellulose was 56% upon microwave heating at 200 • C, nearly identical with the yield (55%) when the hydrolytic process was performed under mainly conventional heating conditions in the SiC reactor. Although the beneficial effect of catalyst selective heating was not reflected in the reaction efficiency, there were substantial changes in the state of adsorption of cellulose on the catalyst surface.

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“…In view of the limited presence of water in cellulose, it was likely to lead to the collisions between OH groups and anomeric C1 of the same ring of glucose thus forming levoglucosan (Scheme 17), which could be easily hydrolyzed into glucose. Even without the addition of any catalyst, the yield of glucose could also be reached to 11.0% with a high selectivity of 75.0% at 220 • C for a vey short time of 1 min [242]. On the basis of this work, it is concluded that cellulose can be hydrolyzed by only moderating the temperature under the heating method of microwave irradiation, making it more industrially favorable.…”

Section: Advanced Heating Methodsmentioning

confidence: 79%