Efficient Conversion of Glucose into 5-Hydroxymethylfurfural by

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Efficient Conversion of Glucose into 5-Hydroxymethylfurfural by Chromium(III) Chloride in Inexpensive Ionic Liquid Lei Hu, Yong Sun, and Lu Lin* School of Energy Research, Xiamen University, Xiamen 361005, China ABSTRACT: An efficient process was developed for the conversion of glucose into 5-hydroxymethylfurfural (HMF) in the relatively low-toxicity and inexpensive catalytic system of chromium(III) chloride (CrCl3 3 6H2O) catalyst and tetraethylammonium chloride (TEAC) ionic liquid. An HMF yield of 71.3% was achieved at 130 °C for only 10 min under conventional oil-bath heating. The TEAC/CrCl3 3 6H2O system was found to be tolerant to high water content and high glucose concentration and could be recycled, exhibiting stable activity after five successive runs. Moreover, satisfactory results were achieved when fructose, sucrose, and cellobiose were used as feedstocks. This work might also provide useful information for the production of HMF from biomass.

1. INTRODUCTION With growing concerns about diminishing fossil resources and global warming, the efficient conversion of renewable biomass into fuels and chemicals has recently attracted considerable attention.1
4 Among the many possible biomass-derived chemicals, 5-hydroxymethylfurfural (HMF) has been recognized as a versatile platform compound that can be used for the production of a wide variety of fine chemicals, polymeric materials, and biofuels (Scheme 1).5
9 In the past few years, the preparation of HMF through the dehydration of biomass-based sugars has received increasing interest. Many researchers have selected fructose as the preferred feedstock,7,10 and excellent HMF yields have been readily achieved using many methods.11
15 However, fructose is not abundant in nature, and its cost is very high, these factors limit the large-scale and sustainable production of HMF from this feedstock. Compared to fructose, its isomer glucose, which is the monomeric unit of cellulose and the most abundant monosaccharide in nature, is a better candidate as a resource for the production of HMF.6 As shown in Scheme 1, the isomerization of glucose into fructose through enolization is essential to produce HMF in high yields from glucose.10,16
18 However, it has been shown that it is much more difficult to convert glucose into HMF in water,19,20 organic solvents21
24 and biphasic systems.22,25 The apparent reason for this difficulty is that glucose tends to form a stable six-membered pyranoside structure that has a low enolization rate.6,26 Thus, efficient conversion of glucose into HMF remains a challenge. Currently, ionic liquids, as green and powerful solvents with some specific properties, are gradually being employed in the production of HMF from glucose.8,26
30 Zhao et al.30 were the first to report a significant HMF yield of nearly 70% from glucose by use of chromium(II) chloride (CrCl2) in 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) at 100 °C for 3 h. Yong et al.29 studied the production of HMF from glucose in 1-butyl-3methylimidazolium chloride ([BMIM]Cl) using CrCl2/NHC (N-heterocyclic carbene) as a catalyst and achieved an HMF yield of 81% by holding the system at 100 °C for 6 h. In subsequent studies, the conversion of glucose into HMF with r 2011 American Chemical Society

high yields of 60% and 89% was also accomplished in [EMIM]Cl with addition of CrCl2 at 100 and 120 °C for 3 and 6 h, respectively.31,32 Nearly 100% yield of HMF from glucose was achieved in a solution of [EMIM]Cl and acetonitrile at 120 °C for 3 h.33 More recently, Hsu et al.34 and Stahlberg et al.35 also studied the dehydration of glucose into HMF in [EMIM]Cl and [BMIM]Cl and discussed the optimal reaction conditions. Although good HMF yields from glucose have been obtained at moderate reaction temperatures, all of the proposed systems have required relatively long reaction times of 3
6 h. In addition, the highly toxic catalyst CrCl26 and expensive imidazolium-based ionic liquids such as [EMIM]Cl or [BMIM]Cl5,11,16 are highly problematic for actual industrial application. Therefore, developing a relatively inexpensive, low-toxicity, high-speed, and highyield system is still necessary and desirable for the production HMF from glucose. Compared to imidazolium-based ionic liquids and CrCl2 catalyst, tetraethylammonium chloride (TEAC) is a commercial and relatively inexpensive ionic liquid,2,36 and chromium(III) chloride (CrCl3 3 6H2O) is a low-toxicity catalyst.6 To the best of our knowledge, TEAC has been employed in only two research articles.2,36 However, in Cao et al.’s report,2 NaHSO4 3 H2O as the catalyst was mainly used for the conversion of fructose. In Yuan et al.’s work,36 a poor yield of HMF from glucose was achieved using CrCl2 as the catalyst. Moreover, it should be noted that, in previous studies, CrCl3 3 6H2O catalyst has largely been used in expensive imidazolium-based ionic liquids.6,18,26 Hence, in our study, both relatively inexpensive TEAC as the solvent and low-toxicity chromium(III) chloride (CrCl3 3 6H2O) as the catalyst were used for the production of HMF with a good yield from glucose. The effects of various reaction parameters on the HMF yield were comprehensively investigated. Furthermore, other substrates such as fructose, sucrose, and cellobiose were also examined in the TEAC/CrCl3 3 6H2O system. Received: September 23, 2011 Accepted: December 20, 2011 Revised: December 19, 2011 Published: December 20, 2011 1099

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Scheme 1. Synthesis of HMF and Its Further Derivatization into Important Chemicals

2. EXPERIMENTAL SECTION 2.1. Materials. Tetraethylammonium chloride (TEAC, 99%), caprolactam (CPL, 99%), and 5-hydroxymethylfurfural (HMF, 99%) were purchased from Shanghai PuGuang Industrial Co. Ltd. (Shanghai, China). 1-Butyl-3-methylimidazolium chloride ([BMIM]Cl, 99%) was supplied by Shanghai ChengJie Chemical Co. Ltd. (Shanghai, China). Anhydrous chromium(II) chloride (CrCl2, 97%) was purchased from Alfa Aesar. All other chemicals were obtained from Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China) and used without further purification. 2.2. General Procedure for the Conversion of Glucose to HMF. The catalytic experiments were performed in an 18 mm  138 mm tube with a lid. In a typical experiment, 100 mg of glucose and various catalysts (10 mol % with respect to glucose) were added to 1 g of TEAC. The tube was sealed, and the reaction mixture was heated in an oil bath at 120 °C and stirred at a speed of 500 rpm for 30 min. After the desired reaction time had elapsed, the reaction mixture was cooled to room temperature immediately. 2.3. Analysis. Four milliliters of deionized water was added to the reaction mixture. Then, the water-containing mixture was

centrifuged at 5000 rpm for 10 min, and a single liquid layer was formed. The HMF concentration was measured by UV
vis spectrophotometer (UV-1750) at 284 nm using the standard curve method, which was similar to the approach used by Li et al.37 and De et al.38 The HMF yield was calculated as HMF yield ð%Þ ¼

moles of HMF  100 initial moles of glucose

ð1Þ

3. RESULTS AND DISCUSSION 3.1. Effect of Catalyst. First, we screened a wide range of catalysts, including mineral acids, organic acids, and metal chlorides, for the production of HMF from glucose in TEAC ionic liquid at 120 °C for 30 min. It can be seen from Figure 1 that the HMF yield was highly dependent on the catalyst. In the absence of catalyst, the yield of HMF was only 2.2%. Among the applied catalysts, H3PO4, HCOOH, CH3COOH, ZnCl2, FeCl2 3 4H2O, MnCl2 3 4H2O, MgCl2 3 6H2O, and LiCl 3 H2O had no obvious catalytic activities in the conversion of glucose and gave 1100

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Figure 1. Effects of different catalysts on HMF yield. (Reaction conditions: 100 mg of glucose and 10 mol % different catalysts were dissolved in 1 g of TEAC at 120 °C for 30 min. Catalyst loading is relative to glucose.)

Figure 2. Effects of reaction temperature and reaction time on HMF yield. (Reaction conditions: 100 mg of glucose and 10 mol % CrCl3 3 6 H2O were dissolved in 1 g of TEAC at different reaction temperatures for different reaction times. Catalyst loading is relative to glucose.)

HMF yields of less than 5%. However, when HCl, H2SO4, HNO3, AlCl3 3 6H2O, FeCl3 3 6H2O, SnCl4 3 5H2O, SnCl2 3 2 H2O, or CuCl2 3 2H2O was used, the HMF yield was improved to a certain degree, with final HMF yields ranging from 10.6% to 40.6%. Compared to the catalysts mentioned above, chromium chlorides were found to be much more effective for the conversion of glucose. More interestingly, CrCl3 3 6H2O with an HMF yield of 70.3% was more active than CrCl2, which is consistent with the results of Zhang et al.31 This result might be because the stronger Lewis acidity of Cr3+ not only lowered the barrier of the isomerization of glucose to fructose but also accelerated the dehydration of fructose into HMF compared to Cr2+.31 Furthermore, the toxicity and the cost of CrCl3 3 6H2O are also much lower than those of CrCl2.6 Thus, CrCl3 3 6H2O was chosen as the superior catalyst for subsequent study. 3.2. Effects of Reaction Temperature and Reaction Time. Experiments were carried out at 100, 110, 120, and 130 °C for different reaction times. The results are shown in Figure 2, from which it can be seen that the reaction temperature and time have

Figure 3. Effect of catalyst loading on HMF yield. (Reaction conditions: 100 mg of glucose and different amounts of CrCl3 3 6H2O were dissolved in 1 g of TEAC at 130 °C for 10 min. Catalyst loading is relative to glucose.)

a significant influence on the production of HMF. When the reaction temperature was 100 °C, the HMF yield of 64.4% was obtained in 120 min of reaction time. When the reaction temperature was increased to 120 °C, the yield of HMF increased to70.3% in 30 min of reaction time. At a reaction temperature of 130 °C, the HMF yield of 71.3% was achieved in 10 min. The results indicated that increasing the reaction temperature not only increased the maximum yield of HMF, but also decreased the reaction time needed to reach the maximum yield of HMF. Moreover, at different reaction temperatures, the HMF yield always first increased with increasing reaction time. When the HMF yield reached its peak value, any further increase in reaction time resulted in lower yields of HMF, which can be attributed to the further condensation of HMF into byproducts.39 Hence, a reaction temperature of 130 °C and a reaction time of 10 min were selected as the optimal conditions for the conversion of glucose into HMF. 3.3. Effect of Catalyst Loading. Figure 3 shows the effect of catalyst loading with respect to glucose on HMF yield. When 5 mol % CrCl3 3 6H2O was used, a yield of HMF of 65.6% was obtained at 130 °C in 10 min. When the amount of CrCl3 3 6H2O increased to 10 mol %, the yield of HMF increased to 71.3%. 1101

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Table 1. Comparison of HMF Yields from Glucose in Different Catalytic Systems HMF concentration T (°C), t (min)

(%)

CPL-LiCl/CrCl2

10

100, 180

58.7

42

[EMIM]BF4/SnCl4

23

100, 180

61.3

28

[BMIM]Cl/Cr-HAP

5

150, 32

32.5

43

[BMIM]Cl/B(OH)3

10

120, 180

41.0

44

ref

5

120, 30

47.5

10

[BMIM]Cl/CrCl3 3 6H2O

30

120, 10

55.0

6

[BMIM]Cl/CrCl3 3 6H2O

10

120, 60

65.0

45

TEAC/CrCl3 3 6H2O TEAC/CrCl3 3 6H2O

5 10

130, 10 130, 10

71.5 71.3

this work this workb

TEAC/CrCl3 3 6H2O

15

130, 10

68.4

this workb

TEAC/CrCl3 3 6H2O

20

130, 10

66.6

this workb

TEAC/CrCl3 3 6H2O

25

130, 10

66.0

this workb

TEAC/CrCl3 3 6H2O

30

130, 10

65.5

this workb

[BMIM]Cl/GeCl4

a

yield

(wt %)a

solvent/catalyst

b

Figure 4. Effect of initial water concentration on HMF yield. (Reaction conditions: 100 mg of glucose and 10 mol % CrCl3 3 6H2O were dissolved in 1 g of TEAC and different initial amounts of water at 130 °C for 10 min. Catalyst loading is relative to glucose, and water content is relative to TEAC.)

Table 2. Successive Uses of TEAC and CrCl3 3 6H2Oa

Glucose concentration is based on reaction solvent. b Reaction conditions: different amounts of glucose and 10 mol % CrCl3 3 6H2O dissolved in 1 g of TEAC at 130 °C for 10 min. Catalyst loading is relative to glucose.

However, when the amount of CrCl3 3 6H2O was further increased to 25 mol %, the yield of HMF decreased to 63.2%. The decrease can be ascribed to the fact that more catalyst accelerated side reactions of HMF such as rehydration or condensation.4,15,40,41 Because the maximum HMF yield was achieved using 10 mol % CrCl3 3 6H2O, we used this catalyst loading for subsequent experiments. 3.4. Effect of Initial Glucose Concentration. The efficient conversion of a high concentration of substrates is crucial for the practical production of HMF. In this work, the effect of initial glucose concentration on HMF yield was investigated. As shown in Table 1, when the initial glucose concentration was 5 and 10 wt %, the yields of HMF were more than 71% at 130 °C for 10 min. Although there was a slight decrease when the initial glucose concentration was further increased from 10 to 30 wt %, an HMF yield of 65.5% was still achieved. Compared to previous studies, our system of TEAC/CrCl3 3 6H2O is more effective for the conversion of high glucose concentrations into high yields of HMF in a shorter time. 3.5. Effect of Water Content. One product of HMF formation is water, which can promote the rehydration of HMF or other side reactions.10,37,46 Because the experiments were performed in an ionic liquid, a nonaqueous environment, the initial water content in the reaction system could be a sensitive issue. To address this concern, the effect of the water content on the HMF yield was tested. As illustrated in Figure 4, when 1 and 5 wt % water were added to the reaction system, the yields of HMF were 74.9% and 76.3%, higher than the 71.3% obtained in the absence of water. These results imply that the presence of a small amount of water in this reaction system could help the reaction, probably because some water not only reduced the viscosity of TEAC, which is beneficial to mass transfer, but also increased the solubility of glucose and CrCl3 3 6H2O in TEAC.8,36 When the initial water content was further increased to 20 and 30 wt %, HMF yields of 69.6% and 62.4%, respectively, were still obtained, which demonstrated that this catalytic system is tolerant to

recycle times

HMF yield (%)

extraction efficiency (%)

1

67.5

>95

2 3

66.4 68.1

>95 >95

4

67.3

>95

5

65.4

>95

a

Reaction conditions: 100 mg of glucose and 10 mol % CrCl3 3 6H2O dissolved in 1 g of TEAC at 130 °C for 10 min. Catalyst loading is relative to glucose.

relatively high water contents and has a great potential to reduce the use of TEAC in the practical production of HMF. 3.6. Recycling of Ionic Liquid and Catalyst. Long-term recyclability of the solvent and the catalyst is an extremely important consideration for practical biomass conversion to reduce production costs. In this work, the reuse of the TEAC ionic liquid and CrCl3 3 6H2O catalyst was tested to study their stability and activity. After the first reaction run, 1 mL of deionized water was added to the reaction mixture to decrease the viscosity of the ionic liquid and facilitate the extraction of HMF.4,6 Then, HMF was separated from the reaction mixture by 10 extractions, each with 5 mL of ethyl acetate. The amount of HMF in ethyl acetate was examined to represent the total HMF yield, and the separation efficiency of HMF was about 95%. After extraction of HMF, the reaction mixture was heated at 65 °C for 24 h in a vacuum oven to remove water and residual ethyl acetate. The dried TEAC and CrCl3 3 6H2O were directly used for the next reaction run by adding an equal amount of glucose under the same reaction conditions. As can be seen from Table 2, the TEAC/CrCl3 3 6H2O system retained a high catalytic activity for the conversion of glucose into HMF, and the yield of HMF still kept above 65% after being recycled five times. Furthermore, the yield of HMF in some recycles was even higher than the first cycle, which is attributed to the retention of HMF and unreacted glucose from the previous cycle.4,6 3.7. Conversion of Glucose in Different Solvents. In addition to various parameters mentioned above, the reaction solvent is also an important factor for the conversion of glucose into HMF. In this work, the effects of other solvents such as CPL, [BMIM]Cl, dimethyl acetylamide (DMA), dimethyl formamide 1102

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into HMF. An excellent HMF yield of 71.3% was achieved at 130 °C for only 10 min. Compared to previous work, high HMF yields were obtained when the initial water content and glucose concentration were as high as 30 wt %. This catalytic system could be reused five times without significant activity loss. In addition, when fructose, sucrose, and cellobiose were used as feedstocks, good results were also obtained.

’ AUTHOR INFORMATION Corresponding Author

*E-mail: [email protected]. Tel./Fax: +86-0592-5952786. Figure 5. Conversion of glucose into HMF in different reaction solvents. (Reaction conditions: 100 mg of glucose and 10 mol % CrCl3 3 6H2O were dissolved in 1 g of different reaction solvents at 130 °C for 10 min. Catalyst loading is relative to glucose.)

Table 3. Conversions of Various Substrates into HMF with TEAC/CrCl3 3 6H2Oa entry

substrate

HMF yield (%)

1

glucose

71.3

2

fructose

73.8

3

sucrose

76.4

4

cellobiose

60.7

a

Reaction conditions: 100 mg of sugar and 10 mol % CrCl3 3 6H2O were dissolved in 1 g of TEAC at 130 °C for 10 min. Catalyst loading is relative to sugar.

(DMF), and dimethyl sulfoxide (DMSO) on the yield of HMF were studied (Figure 5). As can be seen from Figure 5, when CPL, DMF, and DMSO were used as reaction solvents, the yields of HMF were only 46.9%, 42.2%, and 22.4%, respectively. Although a higher HMF yield of 63.9% was obtained from DMA, the separation of HMF from DMA was difficult. [BMIM]Cl was found to be the most effective solvent for the production of HMF from glucose in this work, which is in accordance with the results obtained by Li et al.,26 Qi et al.,6 and Zhang et al.10 However, the HMF yield of 71.3% in TEAC was comparable to that in [BMIM]Cl. Moreover, TEAC is a commercially available and relatively inexpensive ionic liquid,2,36 so it has more advantages in the practical production of HMF from glucose than [BMIM]Cl. 3.8. Conversion of Various Substrates into HMF with TEAC/CrCl3 3 6H2O. The TEAC/CrCl3 3 6H2O system was also tested for catalyzing other substrates to form HMF. As can be seen from Table 3, HMF was obtained in 73.8% yield when fructose was used. When disaccharides such as sucrose, consisting of glucose and fructose, and cellobiose, consisting of two molecules of glucose, were used, good results were also obtained at 130 °C in 10 min with HMF yields of 76.4% and 60.7%, respectively. These results demonstrate that the TEAC/CrCl3 3 6H2O catalytic system is comparable to [EMIM]Cl/CrCl2, SnCl4/[EMIM]BF4, [BMIM]Cl/ CrCl3 3 6H2O, and [BMIM]Cl/GeCl46,10,28,30 and is also suitable for the conversions of fructose, sucrose, and cellobiose.

4. CONCLUSIONS In this study, a new catalytic system based on the low-toxicity catalyst CrCl3 3 6H2O in the relatively inexpensive ionic liquid TEAC has been established for the efficient conversion of glucose

’ ACKNOWLEDGMENT The authors gratefully acknowledge financial support from the National Basic Research Program of China (973 project, 2010CB732201), the National Natural Science Foundation of China (21106121), and the Fundamental Research Funds for the Central Universities (2010121077). ’ REFERENCES (1) Binder, J. B.; Raines, R. T. Simple chemical transformation of lignocellulosic biomass into furans for fuels and chemicals. J. Am. Chem. Soc. 2009, 131, 1979–1985. (2) Cao, Q.; Guo, X. C.; Guan, J.; Mu, X. D.; Zhang, D. K. A process for efficient conversion of fructose into 5-hydroxymethylfurfural in ammonium salts. Appl. Catal. A: Gen. 2011, 403, 98–103. (3) Qi, X. H.; Guo, H. X.; Li, L. Y. Efficient conversion of fructose to 5-hydroxymethylfurfural catalyzed by sulfated zirconia in ionic liquids. Ind. Eng. Chem. Res. 2011, 50, 7985–7989. (4) Wang, P.; Yu, H. B.; Zhan, S. H.; Wang, S. Q. Catalytic hydrolysis of lignocellulosic biomass into 5-hydroxymethylfurfural in ionic liquid. Bioresour. Technol. 2011, 102, 4179–4183. (5) Degirmenci, V.; Pidko, E. A.; Magusin, P. C. M. M.; Hensen, E. J. M. Towards a selective heterogeneous catalyst for glucose dehydration to 5-hydroxymethylfurfural in water: CrCl2 catalysis in a thin immobilized ionic liquid layer. ChemCatChem 2011, 3, 969–972. (6) Qi, X. H.; Watanabe, M.; Aida, T. M.; Smith, R. L. Fast transformation of glucose and di-/polysaccharides into 5-hydroxymethylfurfural by microwave heating in an ionic liquid/catalyst system. ChemSusChem 2010, 3, 1071–1077. (7) Su, Y.; Brown, H. M.; Huang, X. W.; Zhou, X. D.; Amonette, J. E.; Zhang, Z. C. Single-step conversion of cellulose to 5-hydroxymethylfurfural (HMF), a versatile platform chemical. Appl. Catal. A: Gen. 2009, 361, 117–122. (8) Zakrzewska, M. E.; Bogel-Lukasik, E.; Bogel-Lukasik, R. Ionic liquid-mediated formation of 5-hydroxymethylfurfurals: A promising biomass-derived building block. Chem. Rev. 2011, 111, 397–417. (9) Zhang, Y. M.; Degirmenci, V.; Li, C.; Hensen, E. J. M. Phosphotungstic acid encapsulated in metal
organic framework as catalysts for carbohydrate dehydration to 5-hydroxymethylfurfural. ChemSusChem 2011, 4, 59–64. (10) Zhang, Z. H.; Wang, Q.; Xie, H. B.; Liu, W. J.; Zhao, Z. B. Catalytic conversion of carbohydrates into 5-hydroxymethylfurfural by germanium(IV) chloride in ionic liquids. ChemSusChem 2011, 4, 131–138. (11) Caes, B. R.; Raines, R. T. Conversion of fructose into 5-(hydroxymethyl)furfural in sulfolane. ChemSusChem 2011, 4, 353–356. (12) Crisci, A. J.; Tucker, M. H.; Dumesic, J. A.; Scott, S. L. Bifunctional solid catalysts for the selective conversion of fructose to 5-hydroxymethylfurfural. Top. Catal. 2010, 53, 1185–1192. (13) Roman-Leshkov, Y.; Chheda, J. N.; Dumesic, J. A. Phase modifiers promote efficient production of hydroxymethylfurfural from fructose. Science 2006, 312, 1933–1937. 1103

dx.doi.org/10.1021/ie202174f |Ind. Eng. Chem. Res. 2012, 51, 1099–1104

Industrial & Engineering Chemistry Research (14) Shimizu, K. I.; Uozumi, R.; Satsuma, A. Enhanced production of hydroxymethylfurfural from fructose with solid acid catalysts by simple water removal methods. Catal. Commun. 2009, 10, 1849–1853. (15) Zhao, Q.; Wang, L.; Zhao, S.; Wang, X. H.; Wang, S. T. High selective production of 5-hydroymethylfurfural from fructose by a solid heteropolyacid catalyst. Fuel 2011, 90, 2289–2293. (16) Huang, R. L.; Qi, W.; Su, R. X.; He, Z. M. Integrating enzymatic and acid catalysis to convert glucose into 5-hydroxymethylfurfural. Chem. Commun. 2010, 46, 1115–1117. (17) Moliner, M.; Roman-Leshkov, Y.; Davis, M. E. Tin-containing zeolites are highly active catalysts for the isomerization of glucose in water. PANS 2010, 107, 6164–6168. (18) Guan, J.; Cao, Q.; Guo, X. C.; Mu, X. D. The mechanism of glucose conversion to 5-hydroxymethylfurfural catalyzed by metal chlorides in ionic liquid: A theoretical study. Comput. Theor. Chem. 2011, 963, 453–462. (19) Qi, X. H.; Watanabe, M.; Aida, T. M.; Smith, R. L. Catalytical conversion of fructose and glucose into 5-hydroxymethylfurfural in hot compressed water by microwave heating. Catal. Commun. 2008, 9, 2244–2249. (20) Watanabe, M.; Aizawa, Y.; Iida, T.; Aida, T. M.; Levy, C.; Sue, K.; Inomata, H. Glucose reactions with acid and base catalysts in hot compressed water at 473 K. Carbohydr. Res. 2005, 340, 1925–1930. (21) Roman-Leshkov, Y.; Barrett, C. J.; Liu, Z. Y.; Dumesic, J. A. Production of dimethylfuran for liquid fuels from biomass-derived carbohydrates. Nature 2007, 447, 982–986. (22) McNeffa, C. V.; Nowlana, D. T.; McNeffa, L. C.; Yana, B.; Fedieb, R. L. Continuous production of 5-hydroxymethylfurfural from simple and complex carbohydrates. Appl. Catal. A: Gen. 2010, 384, 65–69. (23) Ohara, M.; Takagaki, A.; Nishimura, S.; Ebitani, K. Syntheses of 5-hydroxymethylfurfural and levoglucosan by selective dehydration of glucose using solid acid and base catalysts. Appl. Catal. A: Gen. 2010, 383, 149–155. (24) Yan, H. P.; Yang, Y.; Tong, D. M.; Xiang, X.; Hu, C. W. Catalytic conversion of glucose to 5-hydroxymethylfurfural over SO42
/ZrO2 and SO42
/ZrO2
Al2O3 solid acid catalysts. Catal. Commun. 2009, 10, 1558–1563. (25) Chheda, J. N.; Roman-Leshkov, Y.; Dumesic, J. A. Production of 5-hydroxymethylfurfural and furfural by dehydration of biomassderived mono- and poly-saccharides. Green Chem. 2007, 9, 342–350. (26) Li, C. Z.; Zhang, Z. H.; Zhao, Z. B. Direct conversion of glucose and cellulose to 5-hydroxymethylfurfural in ionic liquid under microwave irradiation. Tetrahedron Lett. 2009, 50, 5403–5405. (27) Stahlberg, T.; Fu, W. J.; Woodley, J. M.; Riisager, A. Synthesis of 5-(hydroxymethyl)furfural in ionic liquids: Paving the way to renewable chemicals. ChemSusChem 2011, 4, 451–458. (28) Hu, S. Q.; Zhang, Z. F; Song, J. L.; Zhou, Y. X.; Han, B. X. Efficient conversion of glucose into 5-hydroxymethylfurfural catalyzed by a common Lewis acid SnCl4 in an ionic liquid. Green Chem. 2009, 11, 1746–1749. (29) Yong, G.; Zhang, Y. G.; Ying, J. Y. Efficient catalytic system for the selective production of 5-hydroxymethylfurfural from glucose and fructose. Angew. Chem., Int. Ed. 2008, 120, 9485–9488. (30) Zhao, H. B.; Holladay, J. E.; Brown., H.; Zhang, Z. C. Metal chlorides ionic liquid solvents convert sugars to 5-hydroxymethylfurfural. Science 2007, 316, 1597–1600. (31) Zhang, Y. M.; Pidko, E. A.; Hensen, E. J. M. Molecular aspects of glucose dehydration by chromium chlorides in ionic liquids. Chem.— Eur. J. 2011, 17, 5281–5288. (32) Zhang, Y. T.; Du, H. B.; Qian, X. H.; Chen, E. Y. X. Ionic liquid
water mixtures: Enhanced Kw for efficient cellulosic biomass conversion. Energy Fuels 2010, 24, 2410–2417. (33) Chidambaram, M.; Bell, A. T. A two-step approach for the catalytic conversion of glucose to 2,5-dimethylfuran in ionic liquids. Green Chem. 2010, 12, 1253–1262. (34) Hsu, W. H.; Lee, Y. Y.; Peng, W. H.; Wu, K. C. W. Cellulosic conversion in ionic liquids (ILs): Effects of H2O/cellulose molar ratios,

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temperatures, times, and different ILs on the production of monosaccharides and 5-hydroxymethylfurfural (HMF). Catal. Today 2011, 174, 65–69. (35) Stahlberg, T.; Sørensen, M. G.; Riisager, A. Direct conversion of glucose to 5-(hydroxymethyl)furfural in ionic liquids with lanthanide catalysts. Green Chem. 2010, 12, 321–325. (36) Yuan, Z. S.; Xu, C. B.; Cheng, S. N.; Leitch, M. Catalytic conversion of glucose to 5-hydroxymethyl furfural using inexpensive cocatalysts and solvents. Carbohydr. Res. 2011, 346, 2019–2023. (37) Li, C. Z.; Zhao, Z. B. K.; Wang, A. Q.; Zheng, M. Y.; Zhang, T. Production of 5-hydroxymethylfurfural in ionic liquids under high fructose concentration conditions. Carbohydr. Res. 2010, 345, 1846–1850. (38) De, S.; Dutta, S.; Saha, B. Microwave assisted conversion of carbohydrates and biopolymers to 5-hydroxymethylfurfural with aluminium chloride catalyst in water. Green Chem. 2011, 13, 2859–2868. (39) Wang, J. J.; Xu, W. J.; Ren, J. W.; Liu, X. H.; Lu, G. Z.; Wang, Y. Q. Efficient catalytic conversion of fructose into hydroxymethylfurfural by a novel carbon-based solid acid. Green Chem. 2011, 13, 2678–2681. (40) Fan, C. Y.; Guan, H. Y.; Zhang, H.; Wang, J. H.; Wang, S. T.; Wang, X. H. Conversion of fructose and glucose into 5-hydroxymethylfurfural catalyzed by a solid heteropolyacid salt. Biomass Bioenergy 2011, 35, 2659–2665. (41) Tan, M. X.; Zhao, L.; Zhang, Y. G. Production of 5-hydroxymethyl furfural from cellulose in CrCl2/Zeolite/BMIMCl system. Biomass Bioenergy 2011, 35, 1367–1370. (42) Chen, T. M.; Lin, L. Conversion of glucose in CPL
LiCl to 5-hydroxymethylfurfural. Chin. J. Chem. 2010, 28, 1773–1776. (43) Zhang, Z. H.; Zhao, Z. B. Production of 5-hydroxymethylfurfural from glucose catalyzed by hydroxyapatite supported chromium chloride. Bioresour. Technol. 2011, 102, 3970–3972. (44) Stahlberg, T.; Rodriguez-Rodriguez, S.; Fristrup, P.; Riisager, A. Metal-free dehydration of glucose to 5-(hydroxymethyl)furfural in ionic liquids with boric acid as a promoter. Chem.—Eur. J. 2011, 17, 1456–1464. (45) Cao, Q.; Guo, X. C.; Yao, S. X.; Guan, J.; Wang, X. Y.; Mu, X. D.; Zhang, D. K. Conversion of hexose into 5-hydroxymethylfurfural in imidazolium ionic liquids with and without a catalyst. Carbohydr. Res. 2011, 346, 956–959. (46) Wei, Z. J.; Li, Y.; Thushara, D.; Liu, Y. X.; Ren, Q. L. Novel dehydration of carbohydrates to 5-hydroxymethylfurfural catalyzed by Ir and Au chlorides in ionic liquids. J. Taiwan Inst. Chem. Eng. 2011, 42, 363–370.

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dx.doi.org/10.1021/ie202174f |Ind. Eng. Chem. Res. 2012, 51, 1099–1104