Crystalline-to-amorphous transformation of cellulose in hot and compressed water and its implications for hydrothermal conversion

Deguchi, Shigeru; Tsujii, Kaoru; Horikoshi, Koki

doi:10.1039/b713655b

Cited by 103 publications

(98 citation statements)

References 31 publications

(65 reference statements)

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“…There are at least two pretreatment methods which may be used to weaken and/or destroy the hydrogen bonds within microcrystalline cellulose. One is to pretreat the cellulose at high temperatures, which may lead to the crystalline-to-amorphous transformation of cellulose, as reported previously in HCW at $300 C. 41 The other is to pretreat the cellulose via ball milling. From the viewpoint of maximizing sugar production, a low-temperature pretreatment condition is preferred to minimize the degradation of sugar products.…”

Section: Further Discussion On Mechanisms Of Cellulose Hydrolysis In Hcwmentioning

confidence: 99%

Effect of ball milling on the hydrolysis of microcrystalline cellulose in hot‐compressed water

2011

AIChE Journal

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Ball milling leads to a considerable reduction in cellulose particle size and crystallinity, as well as a significant increase in the specific reactivity of cellulose during hydrolysis in hot‐compressed water (HCW). Cryogenic ball milling for 2 min also results in a significant size reduction but only little change in cellulose crystallinity and specific reactivity during hydrolysis. Therefore, crystallinity is the dominant factor in determining the hydrolysis reactivity of cellulose in HCW while particle size only plays a minor role. Ball milling also significantly influences the distribution of glucose oligomers in the primary liquid products of cellulose hydrolysis. It increases the selectivities of glucose oligomers at low conversions. At high conversions, the reduction in chain length plays an important role in glucose oligomer formation as cellulose samples become more crystalline. An extensive ball milling completely converts the crystalline cellulose into amorphous cellulose, substantially enhancing the formation of glucose oligomers with high degrees of polymerization. © 2010 American Institute of Chemical Engineers AIChE J, 2011

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Section: Further Discussion On Mechanisms Of Cellulose Hydrolysis In Hcwmentioning

confidence: 99%

Effect of ball milling on the hydrolysis of microcrystalline cellulose in hot‐compressed water

2011

AIChE Journal

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“…For instance, amorphous sugars such as sucrose, glucose (Makower and Dye 1956) and lactose (Torres et al 2011) exhibit a decreasing accessibility for water if stored above certain threshold humidity due to crystallisation. The dominant sugar-based macromolecule of wood cell walls, cellulose is known for its ability to form very stable aggregated structures which are only accessible for water in harsh physical conditions of elevated temperature and pressure (above 200°C and 25 MPa;Deguchi et al 2008). Although cellulose is also thermally degraded under such conditions (Tolonen et al 2011(Tolonen et al , 2013, the crystals are seen to completely dissolve in water under very short reaction times (less than 10 s) forming amorphous cellulose fragments (Deguchi et al 2008;Tolonen et al 2013), which nonetheless re-crystallises upon drying (Tolonen et al 2011).…”

Section: Introductionmentioning

confidence: 99%

“…The dominant sugar-based macromolecule of wood cell walls, cellulose is known for its ability to form very stable aggregated structures which are only accessible for water in harsh physical conditions of elevated temperature and pressure (above 200°C and 25 MPa;Deguchi et al 2008). Although cellulose is also thermally degraded under such conditions (Tolonen et al 2011(Tolonen et al , 2013, the crystals are seen to completely dissolve in water under very short reaction times (less than 10 s) forming amorphous cellulose fragments (Deguchi et al 2008;Tolonen et al 2013), which nonetheless re-crystallises upon drying (Tolonen et al 2011). From this it is seen that cellulose has an innate tendency to form aggregated structures which are partly inaccessible for water.…”

Section: Introductionmentioning

confidence: 99%

Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

2017

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The first drying of wood cell walls from the native state has sometimes been described as producing irreversible structural changes which reduce the accessibility to water, a phenomenon often referred to as hornification. This study demonstrates that while changes do seem to take place, these are more complex than what has hitherto been described. The accessibility of wood cell wall hydroxyls to deuteration in the form of liquid water was not found to be affected by drying, since vacuum impregnation with liquid water restores the native cell wall accessibility. Contrary to this, hydroxyl accessibility to deuteration by water vapour was found to decrease to different levels depending on the drying conditions. Vacuum drying at 60°C for 3 days reduced the accessibility more than drying for 1 day at 103°C without vacuum. Drying for 3 days at 103°C increased the hydroxyl accessibility compared to 1 day. Moreover, the decrease in hydroxyl accessibility to deuteration by water vapour induced by the first drying could be at least partially erased by subsequent vacuum impregnation with liquid water, indicating reversibility. For the drying of solid, non-degraded wood cell walls the results challenge the often supposed process of hornification, understood as a permanent decrease in hydroxyl accessibility to water.

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“…Among them, cellulose is by far the most abundant renewable biomass, with an annual production of approximately 1.5×10 12 tons. Although the yield of starch is also very high, it is primarily used as a source of food (Klemm et al, 2005;Farrell et al, 2006;Deguchi et al, 2008). Establishing the efficient use of cellulose is generally recognized as a key technology.…”

Section: Introductionmentioning

confidence: 99%

Glucose production from hydrolysis of cellulose over a novel silica catalyst under hydrothermal conditions

Wang

Zhang

et al. 2012

Journal of Environmental Sciences

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A novel silica catalyst was synthesized by evaporation-induced self-assembly (EISA) method and tested for the catalytic selective hydrolysis of cellulose to glucose. This silica catalyst exhibited a higher catalytic activity than other oxides prepared by the same method, such as ZrO 2 , TiO 2 , and Al 2 O 3 . Using silica as a catalyst, cellulose was selectively hydrolyzed into glucose with a glucose yield as high as 50% under hydrothermal conditions without hydrogen gas. The silica catalyst was characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results of temperature-programmed desorption of ammonia (NH 3 -TPD) and textural properties indicated that the synergistic effect between strong acidity and a suitable pore diameter of the silica catalyst may be responsible for its high activity. In addition, the catalyst was recyclable and showed excellent stability during the recycle catalytic runs.

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Crystalline-to-amorphous transformation of cellulose in hot and compressed water and its implications for hydrothermal conversion

Cited by 103 publications

References 31 publications

Effect of ball milling on the hydrolysis of microcrystalline cellulose in hot‐compressed water

Effect of ball milling on the hydrolysis of microcrystalline cellulose in hot‐compressed water

Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

Glucose production from hydrolysis of cellulose over a novel silica catalyst under hydrothermal conditions

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