Heterogeneous Aspects of Acid Hydrolysis of α-Cellulose

Xiang, Qian; Lee, Y. Y.; Pettersson, Pär O.; Torget, Robert

doi:10.1385/abab:107:1-3:505

Cited by 185 publications

(120 citation statements)

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“…3,5,7 Different catalysts have been used for this reaction, such as metal chlorides, 4,6 acids, or enzymes. 1,31,32 The most common and widely used enzyme for this saccharification of cellulose is cellulase.…”

Section: Introductionmentioning

confidence: 99%

Enzyme-Catalyzed Hydrolysis of Cellulose in Ionic Liquids: A Green Approach Toward the Production of Biofuels

2010

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We investigated the reactivity and stability of a commercial mixture of cellulases in eight ionic liquids by optical and calorimetric techniques. First, hydrolysis by cellulases from Tricoderma reesei in these ionic liquids was benchmarked against that in aqueous buffer. Only 1-methylimidazolium chloride (mim Cl) and tris-(2-hydroxyethyl)methylammonium methylsulfate (HEMA) provided a medium in which hydrolysis could occur. While hydrolysis at 65 °C is initially much faster in buffer than in these two liquids, it reaches a plateau after 2 h, whereas the reaction progresses monotonically in the two ionic liquids. This difference in the rate of hydrolysis is largely attributed to two factors: (1) the higher viscosity of the ionic liquids and (2) the enzymes are irreversibly denatured at 50 °C in buffer while they are stable to temperatures as high as 115 °C in HEMA. We explored whether fluorescence quenching of aromatic amino acids of the enzymes was indeed a signature of protein denaturation, as has been suggested in the literature, and concluded that quenching is not necessarily associated with denaturation. When it does occur, for example, in the presence of ionic liquids formed from imidazolium cations and chloride anions, it arises from the imidazolium rather than the chloride. Finally, we conclude that HEMA is a promising, novel, green medium for performing cellulose hydrolysis reactions to convert biomass into biofuels. Because of the thermal stability it imparts to enzymes, its ability to solubilize biomass, and the fact that it does not quench tryptophyl fluorescence (thus permitting monitoring of the enzymes by fluorescence spectroscopy), HEMA provides an ideal starting point for the design of ionic liquids, not only for the hydrolysis of biomass, but also for use with a wide spectrum of enzymatic reactions. KeywordsAmino acids, biofuels, biomass, catalysts, cellulose, chlorine compounds, denaturation, enzymes, fluorescence, fluorescence spectroscopy, hydrolysis, ionization of liquids, organic acids, aromatic amino acid, calorimetric techniques, chloride anions, commercial mixtures Arlington, P.O. Box 19065, Arlington, Texas 76019 ReceiVed: December 21, 2009; ReVised Manuscript ReceiVed: March 16, 2010 We investigated the reactivity and stability of a commercial mixture of cellulases in eight ionic liquids by optical and calorimetric techniques. First, hydrolysis by cellulases from Tricoderma reesei in these ionic liquids was benchmarked against that in aqueous buffer. Only 1-methylimidazolium chloride (mim Cl) and tris-(2-hydroxyethyl)methylammonium methylsulfate (HEMA) provided a medium in which hydrolysis could occur. While hydrolysis at 65°C is initially much faster in buffer than in these two liquids, it reaches a plateau after 2 h, whereas the reaction progresses monotonically in the two ionic liquids. This difference in the rate of hydrolysis is largely attributed to two factors: (1) the higher viscosity of the ionic liquids and (2) the enzymes are irreversibly denatured at 50°C in b...

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Section: Introductionmentioning

confidence: 99%

Enzyme-Catalyzed Hydrolysis of Cellulose in Ionic Liquids: A Green Approach Toward the Production of Biofuels

2010

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“…The concentrated acid plays a dual role in biomass hydrolysis. By disrupting its network of intra-and interchain hydrogen bonds, strong acids decrystallize cellulose and make it accessible to reagents (19); and by catalyzing the hydrolysis of glycosidic bonds, strong acids cleave cellulose and hemicellulose into sugars ( Fig. 1) (4).…”

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confidence: 99%

Fermentable sugars by chemical hydrolysis of biomass

Binder

Raines

2010

Proc. Natl. Acad. Sci. U.S.A.

453

293

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Abundant plant biomass has the potential to become a sustainable source of fuels and chemicals. Realizing this potential requires the economical conversion of recalcitrant lignocellulose into useful intermediates, such as sugars. We report a high-yielding chemical process for the hydrolysis of biomass into monosaccharides. Adding water gradually to a chloride ionic liquid-containing catalytic acid leads to a nearly 90% yield of glucose from cellulose and 70-80% yield of sugars from untreated corn stover. Ion-exclusion chromatography allows recovery of the ionic liquid and delivers sugar feedstocks that support the vigorous growth of ethanologenic microbes. This simple chemical process, which requires neither an edible plant nor a cellulase, could enable crude biomass to be the sole source of carbon for a scalable biorefinery.biofuel | carbohydrate | ethanol fermentation | ionic liquid | lignocellulose

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“…Xiang et al have reported such a change in the physical structure of a-cellulose from a fibrous form to a gelatinous form when treated with 65% H 2 SO 4 . The change in the physical form of the a-cellulose was attributed to the disruption of the hydrogen bonding network [23]. Lan et al succeeded in transforming crystalline cellulose isolated from sugar cane bagasse to an amorphous form with the aid of ultrasonic irradiation of 2 wt.…”

Section: Resultsmentioning

confidence: 99%

Isosaccharinic Acid Mediated Fine Chemicals Production from Cellulose

Pulidindi¹

2017

J Fundam Renewable Energy Appl

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Cellulose (Avicel®) is converted to potentially useful products (formic acid, ethylene glycol, and lactic acid). Isosaccharinic acid is identified as the reaction intermediate. Homogeneous aqueous dispersions of cellulose were obtained with the aid of sonication (1 h.). The degradation of the cellulose dispersion was carried out in an alkaline (NaOH) medium under microwave (domestic) irradiation conditions. With 1, 4 and 10 wt. % cellulose dispersions, conversion values of 44, 58 and 54 wt. %, respectively, were observed upon 5 min. of microwave irradiation. The reaction products in each case have been analyzed by 1 H and 13 C NMR. products in the filtrate were analyzed using NMR ( 1 H, 13 C, DEPT) without further separation. In a large scale production process, based on the wide variation in the boiling point of ethylene glycol relative to formic acid and lactic acid, ethylene glycol could be separated using ordinary distillation whereas fractional distillation to be employed for the separation of formic acid and lactic acid from the product mixture as their boiling points are close. 1 H and 13 C NMR spectra of reaction products obtained from 1 wt. % cellulose (aqueous dispersion in alkaline medium) are shown in Figure 2. Two peaks at 61.1 and 168 ppm in the 13 C NMR spectrum were assigned to ethylene glycol and formic acid, respectively. The presence of formic acid, ethylene glycol and lactic acid, were confirmed by the observation of When the initial concentration of the cellulose (in the aqueous dispersion) is increased from 1 to 4 wt. %, a conversion of 58 wt. % is observed. Isosaccharinic Acid Mediated Fine Chemicals Production from Cellulose Journal of Fundamentals of Renewable Energy and Applications Jo1 H and 13C NMR spectra of reaction products obtained from 4 wt. % cellulose (aqueous dispersion in alkaline medium) are shown in Figure 3. The peaks at 20.2, 61.3 and 168.3 ppm in the 13 C NMR spectrum were assigned to lactic acid, ethylene glycol and formic acid. The formation of the afore mentioned chemicals upon cellulose degradation is also confirmed by the presence of 1 H, doublet at 1.18 and 1.20 ppm (lactic acid), Table 1. For comparison, the 1 H and 13 C NMR spectra of authentic samples of formic acid, ethylene glycol and lactic acid are shown in Figure S1 and S2 respectively. Slight up field shift in the δ values of the reaction product formic acid (8.5 ppm, Figure 2 (a)) relative to the authentic sample (7.5 ppm, Figure S1) is attributed to the alkali under atmospheric pressure in the presence of air. The output of the domestic microwave reactor was 900 W. The microwave oven was modified so as to have provision for a distillation column passing through the MW oven (for enhanced safety of operation) as well as a stirring facility during the reaction [21]. The cellulose decomposition reaction was carried out in a batch mode in a round bottom flask with provision for a reflux condenser. Typically, each batch comprise of 10 mL of the aqueous dispersion of cellulose powder (1, 4 and 10 wt. ...

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Heterogeneous Aspects of Acid Hydrolysis of α-Cellulose

Cited by 185 publications

References 10 publications

Enzyme-Catalyzed Hydrolysis of Cellulose in Ionic Liquids: A Green Approach Toward the Production of Biofuels

Enzyme-Catalyzed Hydrolysis of Cellulose in Ionic Liquids: A Green Approach Toward the Production of Biofuels

Fermentable sugars by chemical hydrolysis of biomass

Isosaccharinic Acid Mediated Fine Chemicals Production from Cellulose

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