Single-step conversion of cellulose to 5-hydroxymethylfurfural (HMF), a versatile platform chemical

Su, Yongsheng; Brown, Heather M.; Huang, Xiwen; Zhou, Xiao Dong; Amonette, James E.; Zhang, Z. Conrad

doi:10.1016/j.apcata.2009.04.002

Cited by 397 publications

(247 citation statements)

References 14 publications

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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%

“…It has been suggested that ionic liquids containing the anions Cl -, Br -, NO 3 -, and CF 3 SO 3 -denature enzymes owing to their higher basicity and, hence, higher affinity for hydrogen bonds. 22,40 There are diverse opinions concerning the effect of fluorinated anions, such as BF 4 and PF 6 , on the enzyme's lifetime. Some reports suggest that since charge can be distributed over several fluorine atoms, the hydrogen bond affinity is minimized between the solvent and the enzyme and that, consequently, there is no interference with the internal hydrogen bonding network of the enzyme, maintaining its secondary structure.…”

Section: Introductionmentioning

confidence: 99%

“…Although the highly viscous bmim Cl (Table 1) slows down the rate of cellulase induced hydrolysis of cellulose, 36 it can dissolve a substantial amount of cellulose. 9 As opposed to bmim Cl, cellulose has very limited solubility in bmim PF 6 and bmim BF 4 , whereas the latter keeps the enzyme active. Thus it is very challenging to find the right combination for the cation-anion pair that can form a compromise between the opposing factors of dissolving cellulose, retaining the activity of the enzymes, and having a low viscosity.…”

Section: Introductionmentioning

confidence: 99%

“…36 They reported that the enzymatic activity ceases within an hour of reaction due the presence of a high concentration of chloride ions in the bmim Cl, whereas the activity is retained in bmim BF 4 . Enzymatic activity was monitored as a function of time with cellulose azure (an azo-dye tagged to the cellulose chain), 42 which upon hydrolysis releases the dye, whose absorbance is measured as a signature of the progress of reaction.…”

Section: Introductionmentioning

confidence: 99%

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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%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2010

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“…HMF can be obtained by the acid-catalyzed dehydration of fructose, glucose, sucrose and even cellulose [7,8,[12][13][14]. Recently, a tandem process combining an isomerase enzyme and an acid dehydration catalyst was employed to produce HMF from glucose [15].…”

Section: Introductionmentioning

confidence: 99%

Bifunctional Solid Catalysts for the Selective Conversion of Fructose to 5-Hydroxymethylfurfural

et al. 2010

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Solid catalysts based on SBA-15 silica were designed for the conversion of fructose to 5-hydroxymethylfurfural (HMF). The catalysts incorporate thioether groups that may promote the tautomerization of fructose to its furanose form, as well as sulfonic acid groups to catalyze its dehydration. The materials were characterized by elemental analysis, X-ray diffraction, N 2 adsorption/ desorption, and solid-state 13 C and 29 Si CP/MAS NMR spectroscopy. Functional groups incorporated into mesoporous silica by co-condensation are more robust under the reaction conditions (water at 180°C) than those grafted onto a non-porous silica. The bifunctional mesoporous catalyst achieved a selectivity for HMF of 74% at 66% fructose conversion.

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Oxygenates Synthesis—Homogeneous

Whyman

2011

Encyclopedia of Catalysis

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The current status of direct (from CO/H 2 ) and indirect (via methanol, formaldehyde, dimethyl ether, or methyl acetate) homogeneously catalyzed C 1 chemistry based routes for the selective production of methanol, ethanol, and ethylene glycol (including higher alcohols, diols, and acetate esters), acetic acid, propionic acid and methyl propionate, ethyl and vinyl acetate, acetic anhydride, and methyl formate is described. Whereas none of the direct routes have been commercialized, largely because of low catalytic activities and extreme operating pressure requirements, indirect routes including the Co‐, Rh‐, and Ir‐catalyzed carbonylation of methanol to acetic acid, Rh‐catalyzed carbonylation of methyl acetate to acetic anhydride (and coproduction of both), and Pd‐catalyzed methoxycarbonylation of ethylene to methyl propionate comprise established commercial processes. The majority of these transformations are uniquely homogeneously catalyzed. Although mechanistic pathways associated with the carbonylation of methanol to acetic acid are well established, uncertainty still surrounds the mechanism of the initial step in the reduction of CO, to a putative formyl intermediate, during its direct conversion to oxygenates. A characteristic mechanistic feature of the latter chemistry is the operation of kinetic reaction control that is manifest in the absence of the thermodynamically favored products, hydrocarbons (particularly methane); with the exception of catalysts for methanol manufacture, this behavior is in sharp contrast to that of typical heterogeneous catalysts for synthesis gas reactions.

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Single-step conversion of cellulose to 5-hydroxymethylfurfural (HMF), a versatile platform chemical

Cited by 397 publications

References 14 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

Bifunctional Solid Catalysts for the Selective Conversion of Fructose to 5-Hydroxymethylfurfural

Oxygenates Synthesis—Homogeneous

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