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Sulfated, Mesoporous Niobium Oxide Catalyzed 5Hydroxymethylfurfural Formation from Sugars Ernest Lau Sze Ngee, Yongjun Gao, Xi Chen, Timothy Misso Lee, Zhigang Hu, Dan Zhao, and Ning Yan Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/ie501980t • Publication Date (Web): 25 Aug 2014 Downloaded from http://pubs.acs.org on September 2, 2014

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Industrial & Engineering Chemistry Research

Sulfated, Mesoporous Niobium Oxide Catalyzed 5Hydroxymethylfurfural Formation from Sugars Ernest Lau Sze Ngee‡, Yongjun Gao‡, Xi Chen, Timothy Misso Lee, Zhigang Hu, Dan Zhao, Ning Yan* Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore.

ACS Paragon Plus Environment

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ABSTRACT: The effectiveness of sulfated mesoporous niobium oxide (MNO-S) as a catalyst for the production of 5-hydroxymethylfurfural (5-HMF) from sugar is studied and reported. The structures of the synthesized MNO-S catalysts and commercial Nb2O5 were characterized by Scanning Electron Microscope (SEM) imaging, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier Transform Infrared Spectroscopy (FTIR). Compared with commercial Nb2O5, the MNO-S-based catalysts show much higher surface area and acidity. MNO-S calcinated at 300 ºC was found to be the most effective catalyst in fructose dehydration into 5-HMF in DMSO, with a yield as high as 88%, and excellent recyclability. Furthermore, the Brönsted acid sites on the surface of the catalyst enable hydrolysis and dehydration reactions to occur in a one-pot manner. As such, MNO-S effectively transform a wide scope of sugar substrates such as sucrose, cellobiose and even polysaccharide, inulin, into 5-HMF with reasonable yield.

KEYWORDS: Biomass, Mesoporous materials, Catalysis, Solid acid, HMF


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1. INTRODUCTION Biomass as a source of chemicals is an upcoming topic with increasing importance in sustainable chemistry due to diminishing sources of fossil fuels.1-4 The conversion of sugars to valuable chemicals represents an important part in the chemical processing of biomass resources,5-8 in parallel with lignin9-12 and chitin13-15 conversion. In this regard, the formation of 5-hydroxymethylfurfural (5-HMF) is of central role in carbohydrate-based bio-refinery as 5HMF is a valuable and versatile intermediate that can be transformed into useful products such as pharmaceuticals16, fuels17-20 and polymers.21-24 Despite its usefulness, the production of 5HMF is still not industrially feasible due to high production costs and difficulty in reuse and recycle catalyst and solvent.25 A plethora of acid catalysts have been used in the dehydration of fructose and other sugars to 5-HMF, such as various mineral acids,26 organic acids27,28 and ionic liquids.29,30 However, heterogeneous catalysts have become increasingly attractive due to its environmental benign nature, in addition to its ease of separation.31-35 Among these, niobium oxide and other niobiumcontaining catalysts show good potential as solid acid catalysts, due to their high stability and strong acid properties as demonstrated in various reactions such as esterification, hydrolysis and isomerization.36-42 Recently, a novel, low-cost synthetic protocol to prepare mesoporous niobium oxide (MNO) solid acid nanocatalysts was developed.43,44 The new procedure makes use of the solventantisolvent effect to synthesize the mesoporous niobium oxide nanomaterials. The submicrometer size of these nanomaterials provides a balance between efficient surface area and recyclability. MNO can be functionalized with acid groups such as sulfate anions (termed as MNO-S), and these MNO-based catalysts were found to exhibit excellent performance in various


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acid-catalysed reactions such as esterification, Friedel-Crafts alkylation and hydrolysis of acetates.43,45 However, the effectiveness of these promising materials in 5-HMF formation reaction has yet to be tested. In this paper, the employment of sulfated MNO as a catalyst in sugar dehydration reaction is investigated. The catalyst was found to provide excellent yield of 5-HMF from fructose in dimethyl sulfoxide (DMSO) solvent. The acidity and morphology of the catalyst were thoroughly characterized, based on which their catalytic performance was rationalized. The reaction condition optimization, reaction kinetics, substrate scope, catalyst recyclability were carefully examined. 2. EXPERIMENTAL SECTION 2.1. Chemicals. Niobium ethoxide (99.9 %, Strem Chemicals), diethylene glycol (DEG, 99 %, Sigma-Aldrich), Nb2O5 particles (99.9 %, Alfa Aesar), sulfuric acid (95-97%, Merck), toluene (99.99 %, Fisher), dimethyl sulfoxide (DMSO, 99.5 %, Sigma-Aldrich) , N-methylpyrrolidone (NMP, 99.5 %, Sigma-Aldrich), dimethylformamide (DMF, HPLC grade, Fisher), ethanol (ACS reagent, Merck), methanol (HPLC grade, TEDIA), fructose (>99 %, Sigma-Aldrich), glucose (ACS reagent, Merck), inulin (ACS reagent, Sigma-Aldrich), cellubiose (BR, sinopharm,Chemical Reagen Co. Ltd), sucrose (AR, sinopharm,Chemical Reagen Co. Ltd), zirconium oxide (DUPONT), nafion® NR50 (Sigma-Aldrich), Amberlyst-15® (H Form, Sigma-Aldrich), Amberlyst® IR 120 (H Form, Sigma-Aldrich). 2.2. Synthesis of MNO-S Catalysts. The experimental procedure for the synthesis of MNO-S catalysts is slightly modified from a literature procedure.43 The preparation of MNO-S begins with the synthesis of glycolated


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niobium oxide nanomaterials (GNO). Niobium ethoxide (0.6 mL) was added to diethyl glycol (DEG) (50.0 mL) in a wide-mouth bottle under vigorous stirring and the system was then bubbled with nitrogen for 0.5 h to remove water and oxygen. Afterwards, the bottle was sealed with Parafilm and stirred for 12 h at room temperature. Thereafter, the mixture was poured into acetone (200 mL) and stirred for 1 h. The white precipitate was collected through centrifugation, washed with ethanol, and then dried at 60 ºC in an oven. In order to synthesize MNO, the GNO as obtained above (approx. 0.4 g) was dispersed in water (40.0 mL) by ultrasonication for 15 min. The mixture was then transferred into a Teflonlined autoclave and heated in an oven at 180 ºC for 12 h. Thereafter, the precipitate was collected through centrifugation and dried at 60 ºC. In preparation for the MNO-S catalysts, the MNO as obtained above (approx. 0.25 g) were calcined at 500 ºC to remove residual DEG. It was then dispersed in methanol solution (20.0 mL) containing sulfuric acid (1.0 M) under stirring for 4 h. The precipitate was collected through centrifugation and calcined at different temperature, such as 100 ºC, 300 ºC and 400 ºC for 4 h. The obtained sample was labeled as MNO-S-100, MNO-S-300 and MNO-S-400, respectively. 2.3. Synthesis for sulfated ZrO2 Sulfated ZrO2 was prepared according to a literature method.46 In a general procedure, 5 g ZrO2 (5 g) was dispersed in sulfuric acid solution (1 M, 50 ml). The solution was stirred for 24 hours at room temperature and then was filtered. The solid was dried at 105 ºC for 12 hours and then calcined at 600 ºC for 2 hours. 2.4. Procedure for Sugar Dehydration Reactions and Product Analysis. In a typical reaction, sugar (0.18 g), catalyst (0.018 g) and solvent (2 mL) were mixed together in a thick-wall glass tube. The tube was heated in an oil bath to the desired temperature, while


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exposed to atmospheric conditions under stirring. After the reaction, the volume of reaction mixture was adjusted to 25 mL by using water and the products of the reaction were then analyzed using High Performance Liquid Chromatography (HPLC). The HPLC measurements were conducted on an Agilent 1200 Series VWD- and DADequipped HPLC system, with the use of an Agilent Hi-Plex H, (7.7 x 300 mm) column. The mobile phase was 0.005M H2SO4 with a flow rate of 0.5 mL/min. The column temperature was set at 50 ºC. Calibration curves were plotted by using a series of standard solutions and used for the quantification of fructose (and other sugars) and 5-HMF. 2.5. Catalyst Characterizations. Pyridine adsorption was employed to probe the acid sites on the MNO-S materials by FTIR analysis. The FTIR spectra were recorded on a Biorad FTS-3500 Spectrometer and the solid samples were mixed with KBr and pressed into a pellet for measurement. The pyridine adsorption was conducted in this procedure: first, the catalyst sample (0.005 g) was heated at 100 ˚C and swept by the nitrogen gas for 30 min to remove water and other substances. Next, the nitrogen gas was bubbled through pyridine before it passed the catalyst sample at room temperature to initiate the adsorption. Finally, pyridine was removed and pure nitrogen was flowed through the catalyst sample at room temperature for 20 min to remove non-adsorbed substances. The morphology of the catalysts was characterized using XPS and XRD. XPS spectra were recorded on a Kratos Axis UltraDLD spectrometer, using mono Al Kα X-ray source (hν=1486.71 eV, 5 mA, 15 kV) with a base pressure of 1×10-9 Torr and a working pressure of 5×10-9 Torr. The angle between the sample surface and detector is set at 90 ˚C. The data were calibrated by the C 1s signal (285.0 eV) and further processed. XRD spectra were recorded on a Bruker D8


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Advanced Diffractometer using Cu Kα (λ=1.5406 Å) radiation (40 kV voltage, 30 mA cathodic current). Diffraction patterns were recorded within a 2θ range of 5-80° in a period of 32 min. Scan electron microscopy (SEM) images were taken at a JSM-6700F field-emission microscope operationg at 15 KV. The sample were immobilized on copper holder by conducting resin and coated by platinum at 30 mA for 30 seconds before characterization. Transmission electron microscopy (TEM) images were taken on a JEOL JEM-2010 microscope operating at 200 KV. The samples were dispersed in water by ultrasonication and then dropped on a copper grid. Gas sorption isotherms were measured using a Micrometrics ASAP 2020 surface area and pore size analyzer. Prior to the measurement, MNO-S-100 was out-gassed at 100 ºC and other materials were out-gassed at 150 ºC for at least 6 h. The BET specific surface areas were calculated using the adsorption data in the relative pressure (P/P0) range of 0.05-0.25. The total pore volumes were estimated from the amount adsorbed at a relative pressure P/P0 of 0.98. The inductively coupled plasma optical emission spectrometry (ICP-OES) was recorded on a Thermo Scientific iCAP 6000 series ICP spectrometer. 2.6. Catalyst Recycling. In order to test the recyclability, the catalyst was reused over four reaction cycles. After each reaction cycle, the catalyst was separated from the mixture through centrifugation, and then washed with toluene, dried and used for the next reaction cycle. The reaction conditions for each cycle were identical, as following: fructose (0.18 g), catalyst (0.018 g) and DMSO (2 mL) were reacted at 120 ˚C under stirring for 2 h. In order to recycle the catalyst, the entire mixture was passed through a syringe filter (Teflon, 0.22 µm) after the reaction, along with toluene to wash the catalyst, after which the syringe filter containing the catalyst residue was dried at 60 ºC for


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12 h and weighed again to accurately determine the weight of catalyst retained. Afterwards the dried catalyst was used directly for the next batch without any further treatment. 2.7 ICP-OES analysis. After reaction, the catalyst was filtered out and the filtrate solution was collected into a volumetric flask, then HNO3 (1 %) was added to adjust the final volume to 25 mL. The resulting solution was measured with ICP-OES to determine the concentration of niobium. 3. RESULTS AND DISCUSSION 3.1. Structural Characterization of MNO-S. 3.1.1 Characterization of morpholpgy and pore structure The morphologies, surface area and pore volumes of both commercial Nb2O5 and MNO-S were characterized and compared by SEM and BET analysis. In the synthetic procedure, niobium ethoxide was used as the precursor so that ethanol molecules would be generated during the preparation of MNO, which in turn created mesoporous structure of the Nb2O5 when the materials were calcined at high temperature due to the evaporation of ethanol, which is strikingly different from the morphology of the commercial Nb2O5. From SEM analysis, commercial Nb2O5 is highly agglomerated bulk material and no porous structure can be observed (Figure 1 and Figure S1). However, it is clear from the SEM images (Figure 1b-c) that the MNO after acid treatment and calcination are all consisting of small particles, and these particles assembles into porous structures. Only a slight degree of aggregation was observed and calcination seems to show no appreciable impact on the morphology (Figure S1b-c). TEM analysis for commercial Nb2O5 and MNO-S-300 were also conducted, and the existence of mesopores in MNO-S-300 is further suggested (Figure S2).


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Figure 1. High resolution SEM images of a) commercial Nb2O5, b) MNO-S-100, c) MNO-S-300, d) MNO-S-400. The nitrogen sorption isotherms of sulfated MNO and commercial Nb2O5 are displayed in Figure 2. Commercial Nb2O5 exhibits essentially no adsorption during the measurement, demonstrating it is a non-porous material. Such non-porous materials are generally not effective in catalysis due to their very small surface area. On the other hand, all three sulfated MNO materials exhibit obvious hysteresis loops in their isotherms suggesting their mesoporous structure. The pore volumes of the three samples are almost the same. However, the pressure at the initial point of hysteresis loop in the isotherms of MNO-S-100 and MNO-S-300 is lower than that in MNO-S-400 isotherm. Besides, the BET surface areas of sulfated MNOS materials decrease when the calcination temperature increases during the sulfation of MNO (from 131.0 m2/g for MNO-S-100, to 111.6 m2/g for MNO-S-300, and to 73.5 m2/g for MNO-S-400). The


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BET results reveal more information on the mesopores and indicate that some pore structures were damaged when the calcination temperature increases.

Figure 2. The N2 adsorption-desorption curves of a) commercial Nb2O5, b) MNO-S-100, c) MNO-S-300 and d) MNO-S-400. 3.1.2 Characterization of crystal structure The XRD patterns of sulfated MNO and commercial Nb2O5 are presented in Figure 3. A significant number of diffraction peaks were present in the commercial Nb2O5, indicating that this material has a complex polymorphic structure.47 According to previous literatures, the structure of stoichiometric Nb2O5 is polymorphism containing a few crystalline phases.48,49 In general, the types of the phases were divided and named according to the processing temperature: i.e., TT-(about 500 ºC), T-(about 600 ºC), M-(about 800 ºC), H-(about 1000 ºC) Nb2O5.36,50,51 The X-ray diffraction patterns of sulfated MNO samples are much simpler. MNO-S-100, MNOS-300 and MNO-S-400 exhibit diffraction peaks at 2θ = 22.6º, 28.5º, 46.2º, 50.7ºand 55.1º which are ascribed to the diffractions of (001), (100), (101), (002), (110) and (102) facets,


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respectively, of a pseudo-hexagonal niobium oxide crystal (TT-phase).43,52 The domination of TT-phase is not unreasonable as the MNO were calcined at 500 ºC in the synthesis to remove organic stabilizing agent, which is the right temperature regime for the formation of TT-phase. Noteworthy, the XRD patterns of all the three sulfated MNO are very similar, suggesting different calcination temperature after treating with sulfuric acid do not affect the crystalline structure of the MNO material. The broad band between 21º and 42º suggest that some of the MNO materials may exist in the amorphous form.

Figure 3. XRD patterns of commercial Nb2O5, MNO-S-100, MNO-S-300 and MNO-S-400. 3.1.3 Characterization of catalyst acidity The XPS spectra of S 3p bands in the sulfated MNO samples (Figure 4a) suggest the presence of sulfur. The peak at 169.3 eV and the weak shoulder peak at 170.4 eV are ascribed to the 2p3/2 and 2p1/2 binding energy of S6+,53-55 indicating successful introduction of sulfonic groups or sulfates onto the surface of MNO. As expected, there is no peak in XPS spectrum of S 3p region for commercial Nb2O5. The XPS spectra of Nb 3d bands in sulfated MNO and commercial Nb2O5 are provided in Figure 4b. The spectrum of Nb2O5 has two obvious peaks at 207.4 eV and 210.1 eV correspond to 3d5/2 and 3d3/2 band respectively.56-59 The 3d5/2 and 3d3/2 binding energy


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of all sulfated MNO materials are higher than commercial Nb2O5, which may be induced by the strong electron withdrawing effect of sulfonic groups, further testifying the presence of -SO3H group on the MNO-S materials. Interestingly, the 3d5/2 and 3d3/2 binding energies of Nb in MNOS-400 are higher than that in MNO-S-100 and MNO-S-300, suggesting the decreased interaction between S and Nb after high temperature treatment due to the partial loss of sulfur components. This assumption was supported by the content of sulfur in MNO-S materials based on XPS analysis, which indicate the surface sulfur content to be 9.4 wt% for MNO-S-100 and 11.0 wt% for MNO-S-400, but lower for MNO-S-400 (7.1 wt%).

Figure 4. XPS spectra of a) S and b) Nb of Nb2O5, MNO-S-100, MNO-S-300 and MNO-S-400. In order to examine the amount of acid sites as well as the acid strength, FTIR spectra of pyridine adsorbed commercial Nb2O5, non-sulfated MNO, and sulfated MNO, were recorded (Figure 5). Sulfate absorption bands between 1250 and 1000 cm-1 can be observed in the sulfated MNO catalysts. For MNO-S-100 and MNO-S-300, the obvious peaks at 1221 and 1140 cm-1 can be attributed to asymmetric and symmetric stretching of S=O bonds respectively, while the peak at 1054 cm-1 is ascribed to the asymmetric stretching of S-O bonds.43 For MNO-S-400, these peaks intensities are much weaker than the ones in MNO-S-100 and MNO-S-300, which can be


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attributed to the decomposition of some of the sulfate species at 400 ºC, in full agreement with XPS analysis. It is well established that pyridine interacting with Lewis and Brönsted acids has different infrared spectra. Pyridine is protonated at Brönsted acid sites with a specific IR wavelength around 1540-1545 cm-1, whereas the coordination between pyridine and Lewis acid sites is featured by a specific IR absorption band at 1449-1452 cm-1. In addition to these, a band at around 1485-1490 cm-1 is characteristic to both species. The absence of a peak at around 1450 cm-1 indicates that none of these materials contain appreciable amount of Lewis acid sites. On the other hand, the absorption associated with Brönsted acid sites can be clearly seen (1543, 1485 cm-1) for MNO-S-100, MNO-S-300 and MNO-S-400.60,61 The wavenumber of the band corresponding to protonation at Brönsted acid sites is the same for the three sulfated samples, suggesting different calcination temperature do not alter the strength of the acidity. The peak intensities, however, are different among the three, with MNO-S-100 exhibiting the most prominent pyridine absorption bands. This indicates higher temperature will decrease the acid content in the MNO-S. The influence of this will be further discussed and addressed in the section concerning catalyst recycling.


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Figure 5. FTIR spectra of pyridine adsorbed on the sulfated MNO, non-sulfated MNO and commercial Nb2O5. 3.2 Catalytic Activity Evaluation 3.2.1 Catalyst selection The effectiveness of MNO, MNO-S-100, MNO-S-300, MNO-S-400, and commercial Nb2O5, in sugar dehydration into 5-HMF was compared. Fructose was selected as a model substrate, which was converted over 10 wt% of catalyst in DMSO at 120 ºC for 10 min (Table 1). Commercial Nb2O5 and non-sulfated MNO were almost inactive in the reaction (Table 1, entry 4, 5), whereas sulfated MNO nanomaterials are much more effective (Table 1, entry 1-3). MNO-S400 is less active compared with the other two, which can be easily rationalized by the fact that high temperature calcination resulted in a smaller number of acid sites (from XPS and FTIR analysis) and decreased surface area (BET analysis). MNO-S-100 and MNO-S-300 are both excellent catalysts for the reaction; within 10 minutes, ca. 70% yield of 5-HMF was achieved (Table1, entry 1 and 2). Compared with the performance of other solid acid catalysts, such as


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sulfated SnO2-ZrO2,62 sulfated ZrO2,63-65 Nafion,63,66 H-BEA zeolite,63,66 Amberlyst-15,66 SBA15-SO3H67 and Cs2.5H0.5PW12O40,68 in the literatures, MNO-S catalysts are among the most active catalysts for the conversion of fructose to HMF (a detailed activity comparison is provided in Table S1). Nevertheless, it is not possible to conduct a fair comparison of the catalytic activity, due to the different reaction conditions employed in the literatures. As such, we use four classical solid acid catalysts, including Amberlyst-15, Amberlyst IR 120, Nafion NR50, and sulfated ZrO2 to catalyze the reaction under the same conditions (Table 1, Entry 6-9). Amberlyst-15 and Amberlyst IR 120 exhibited low activity, not unexpected though, considering their weaker acidity. Nafion NR50 and sulfated ZrO2 were more active, both resulting in 24 % HMF yield under the conditions employed, but were much less effective compared with MNO-S-100 and MNO-S-300. The lower activities for Nafion NR50 and sulfated ZrO2 may result from their much smaller surface area. In addition, it is suggested in the literature that the water generated during the dehydration of fructose can deactivate sulfated ZrO2.46 These control experiments demonstrated the superiority of our sulfated MNO catalysts, likely due to their high surface area and the strong acidity. Table 1. Fructose dehydration into 5-HMF over different catalysts. a Surface area Conversion (mol %)

Yield (mol %)

131.0

96

72

MNO-S-300

111.6

88

65

3

MNO-S-400

73.6

71

45

4

MNO

-

10

1.6

5

Nb2O5

2.1

-

1.9

Entry

Catalyst

1

MNO-S-100

2

(m2/g)


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6

Amberlyst-15

4569

53.2

3.0

7

Amberlyst IR120

-

44.7

12.7

8

Nafion NR50

< 169

43.2

23.9

9

Sulfated ZrO2

1446

34.2

24.1

a. Reaction conditions: 0.018 g catalyst, 0.18 g fructose, 2 mL DMSO, 120 ºC, 10 min.

3.2.2 Recyclability test In order to test the stability and prove the superiority of MNO-S-100 and MNO-S-300 catalysts, we examined their recyclability in the fructose dehydration reaction. For MNO-S-300, the catalysts can be easily separated and reused after each reaction through centrifugation and washed with toluene, highlighting the advantages of this recoverable heterogeneous catalyst. The recyclability of MNO-S-300 over four cycles was shown in Figure 6a. A full conversion of fructose was observed in four consecutive runs and yield of 5-HMF only dropped slightly. After four batches, MNO-S-300 retained ca. 90% of its original activity in producing 5-HMF from fructose. Accordingly, the weight of the recovered catalyst remained constant after recycling, indicating neglectable leaching of the catalyst into the solution phase. The recyclability of MNOS-100 was also tested. In the first batch, the 5-HMF yield from MNO-S-100 appeared to be similar to that of MNO-S-300 (72% vs 78%), which is congruent with the results found from the acidity characterization study. However, the 5-HMF yield experienced a significant drop from the second cycle, implying that the calcination temperature of 100 º C is not sufficient to immobilize the sulfate groups onto the catalyst, and acid leaches from the catalyst into the solution during reactions. FTIR spectra of the recycled catalysts (Figure 6b) show that the peak intensities related to the sulfate groups have decreased significantly for MNO-S-100 after usage,


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further confirming the loss of sulfate groups. In addition, the surface area of used MNO-S-100 and used MNO-S-300 were analyzed by nitrogen adsorption experiment (Figure 7). Both the surface area (from 131.0m2/g to 215.4 m2/g) and the pore volume (from 0.16cm3/g to 0.21 cm3/g) for MNO-S-100 increased after catalysis. For MNO-S-300, no the other hand, the surface area (from 111.6m2/g to 126.5 m2/g) and pore volume (from 0.13cm3/g to 0.11 cm3/g) exhibited no significant change. These results illustrate that the sulfur acid or acidic group in the pores of MNO-S-100 were leached in the reaction, leading to increased surface area and pore volume of the catalyst, whereas the acidic groups embedded on MNO-S-300 were stable during the reaction. This conclusion is in accordance with the FTIR analysis. After reaction with MNO-S300 as the catalyst, the Nb content in the solution is below the detection limit of ICP-OES, indicating neglectable leaching of Nb. Because MNO-S-300 has a much higher stability, it was chosen for further experiments.

Figure 6. a) Recycling experiments catalyzed by MNO-S-300. (Reaction conditions: 0.018 g catalyst, 0.18 g fructose, 2 mL DMSO, 120 ºC, 2 h. b) FTIR spectra of both recycled (MNO-S300-R and MNO-S-100-R) and non-recycled (MNO-S-300 and MNO-S-100).


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Figure 7.The N2 adsorption-desorption curves of a) used MNO-S-100 and b) used MNO-S-300. 3.2.3 Solvent screening and kinetic study MNO-S-300 was used in the fructose dehydration reaction in various solvents (Table 2, entry15). In addition to DMSO, N-methylpyrrolidone (NMP), N,N-dimethyl-formamide (DMF), H2O and dimethylacetamide (DMA) were tested under the same reaction conditions. Water is the worst solvent with little 5-HMF produced, not unexpected though, as the dehydration reaction is inherently inhibited by water, and that water promote the formation of by-products such as levulinic acid, formic acid, and humins.32,66 NMP provides certain amount of 5-HMF but the yield is low, which can be rationalized by the fact that the basicity of NMP compromise the effectiveness of Brönsted acidic catalyst. DMSO appears to be the most effective solvent in which MNO-S-300 can effectively catalyze the reaction, which is consistent with previous researches that DMSO is an excellent solvent for the dehydration of fructose, as it can effectively suppress the undesired side reactions.

60, 70-72

A study of the reaction kinetics was performed at

90 ºC (Figure 8). The reaction seemed to reach its peak at approximately 2 h with a fructose conversion of 97% and HMF yield of 72%. A further increase of 5-HMF yield can be achieved via increasing the reaction temperature. For example, at 120 ºC, 88.1 % 5-HMF yield was obtained after 5 h (Table 2, entry 5).


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Figure 8. Effect of time on conversion and yield, reaction conditions: 0.018 g catalyst, 0.18 g fructose, 2 mL DMSO, 90 ºC. 3.2.4 Substrate scope of MNO-S-300 in sugar dehydration Noteworthy, MNO-S-300 is a solid Brönsted acid and is able to catalyze the hydrolysis reaction, which enable a tandem hydrolysis-dehydration pathway transforming disaccharide, oligosaccharides and even polysaccharides into 5-HMF in a one-pot manner. The substrate scope of the catalyst was examined with glucose, sucrose, inulin and cellobiose (Table 2 entry 10-15). MNO-S-300 turned out to be very effective in the dehydration of sugars containing fructose units. For example, inulin, which can be regarded as a heterogeneous collection of fructose polymers, can be readily converted into 5-HMF with over 60 % yield. On the other hand, its performance over sugars containing glucose units is limited. For both glucose and cellobiose, the 5-HMF yields were low. The low efficiency of the MNO-S-300 catalyst in the dehydration of glucose unit can be attributed to the lack of Lewis acid sites (based on Pyridine absorption experiment), which is essential to promote the transformation from glucose to fructose. Sucrose, which is made up of one fructose and one glucose unit, was converted to 5-HMF with a yield close to 50 %, furthering indicating the drastically different activity of MNO-S-300 for fructose


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and glucose conversion. Since water is required for the hydrolysis of sucrose, one equivalent water was added into the reaction system to test the effect of water (Table 2 entry 13). Indeed, the yield of HMF increased significantly from 45.6 % to 72.6 %, indicating a small amount of water is beneficial to the production of HMF when glycosidic bond exists in the substrate, plausibly by accelerating sugar hydrolysis. Table 2. Sugar dehydration over MNO-S-300 under different reaction conditions.a

Entry

Substrate

solvent

Time (h)

Temp. (oC)

Yield (mol%)

1

Fructose

NMP

2

90

11.7

2

Fructose

DMF

2

90

0.18

3

Fructose

H2O

2

90

0.22

4

Fructose

DMA

2

90

1.6

5

Fructose

DMSO

2

90

62.5

6

Fructose

DMSO

2

110

76.7

7

Fructose

DMSO

2

120

82.0

8

Fructose

DMSO

5

120

88.1

9

Glucose

DMSO

2

110

1.1

10

Glucose

DMSO

2

120

1.7

11

Glucose

DMSO

5

120

5.2

12

Sucrose

DMSO

5

110

45.6

13b

Sucrose

DMSO

5

110

72.6

14

Inulin

DMSO

5

110

59.8

15

Cellobiose

DMSO

5

120

10.2

a Reaction conditions used: 0.018 g catalyst, 0.18 g substrate, 2 mL solvent. b 1 eq. water was added before the reaction.


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4. CONCLUSIONS The effectiveness of MNO-based catalysts in the sugar dehydration reaction was investigated and the acidity and morphology of the catalyst were characterized and studied. The sulfated MNO catalyst, calcinated at 300 º C, was found to be highly effective in catalyzing the dehydration of fructose into 5-HMF in DMSO, with a yield as high as 88%, and excellent recyclability. MNO-S-300 can catalyze both the hydrolysis and the dehydration reaction, enabling the transformation of disaccharide, oligosaccharides and polysaccharides into 5-HMF in a one-pot manner. The work presented here provides an effective solid acid catalyst for sugar dehydration, enriching the catalyst toolbox for bio-refinery. Due to the lack of Lewis acid sites, MNO-S cannot effectively promote the isomerization reaction between glucose and fructose. Incorporation of Lewis acid sites in the material might be a solution to further expand the substrate scope of the catalyst in 5-HMF production. ASSOCIATED CONTENT Supporting Information. Some TEM and SEM images with high resolution and comparison of catalytic activity were supplied as Supporting Information. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author * E-mail: [email protected] Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. ‡These authors contributed equally.


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ACKNOWLEDGMENT We sincerely thank Prof. Huachun Zeng for guiding the catalyst synthesis and we acknowledge the PSF funding from A*Star, Singapore (WBS: R-279-000-403-305) and a Tier-1 project from Ministry of Education, Singapore (WBS: R-279-000-387-112) for the financial support.


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REFERENCES (1)

Huber, G. W.; Iborra, S.; Corma, A. Synthesis of Transportation Fuels from Biomass:

Chemistry, Catalysts, and Engineering. Chem. Rev. 2006, 106, 4044-4098. (2)

Yan, N.; Dyson, P. J. Transformation of biomass via the selective hydrogenolysis of CO

bonds by nanoscale metal catalysts. Curr. Opin. Chem.Eng. 2013, 2, 178-183. (3)

Ragauskas, A. J.; Williams, C. K.; Davison, B. H.; Britovsek, G.; Cairney, J.; Eckert, C.

A.; Frederick, W. J.; Hallett, J. P.; Leak, D. J.; Liotta, C. L.; Mielenz, J. R.; Murphy, R.; Templer, R.; Tschaplinski, T. The Path Forward for Biofuels and Biomaterials. Science 2006, 311, 484489. (4) Gallezot, P. Conversion of biomass to selected chemical products. Chem. Soc. Rev. 2012, 41, 1538-1558. (5)

Tong, X.; Ma, Y.; Li, Y. Biomass into chemicals: Conversion of sugars to furan

derivatives by catalytic processes. Appl. Catal. A: Gen. 2010, 385, 1-13. (6)

Wang, T.; Nolte, M. W.; Shanks, B. H. Catalytic dehydration of C6 carbohydrates for the

production of hydroxymethylfurfural (HMF) as a versatile platform chemical. Green Chem. 2014, 16, 548-572. (7)

Meng, X.; Ragauskas, A. J. Recent advances in understanding the role of cellulose

accessibility in enzymatic hydrolysis of lignocellulosic substrates. Curr. Opin. Biotechnol. 2014, 27, 150-158. (8)

Yabushita, M.; Kobayashi, H.; Fukuoka, A. Catalytic transformation of cellulose into

platform chemicals. Appl. Catal. B: Environ. 2014, 145, 1-9.


23


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(9)

Page 24 of 33

Zhang, J.; Asakura, H.; Van Rijn, J.; Yang, J.; Duchesne, P.; Zhang, B.; Chen, X.; Zhang,

P.; Saeys, M.; Yan, N. Highly efficient, NiAu-catalyzed hydrogenolysis of lignin into phenolic chemicals. Green Chem. 2014, 16, 2432-2437. (10) Zhang, J.; Teo, J.; Chen, X.; Asakura, H.; Tanaka, T.; Teramura, K.; Yan, N. A Series of NiM (M = Ru, Rh, and Pd) Bimetallic Catalysts for Effective Lignin Hydrogenolysis in Water. ACS Catal. 2014, 4, 1574-1583. (11) Gao, Y.; Zhang, J.; Chen, X.; Ma, D.; Yan, N. A Metal-Free, Carbon-Based Catalytic System for the Oxidation of Lignin Model Compounds and Lignin. ChemPlusChem 2014, 79, 825-834. (12) Zakzeski, J.; Bruijnincx, P. C. A.; Jongerius, A. L.; Weckhuysen, B. M. The catalytic valorization of lignin for the production of renewable chemicals. Chem. Rev. 2010, 110, 35523599. (13) Chen, X.; Chew, S. L.; Kerton, F. M.; Yan, N. Direct conversion of chitin into a Ncontaining furan derivative. Green Chem. 2014, 16, 2204-2212. (14) Pierson, Y.; Chen, X.; Bobbink, F. D.; Zhang, J.; Yan, N. Acid-Catalyzed Chitin Liquefaction in Ethylene Glycol. ACS Sustainable Chem. Eng. 2014, 2, 2081-2089. (15) Kerton, F. M.; Liu, Y.; Omari, K. W.; Hawboldt, K. Green chemistry and the oceanbased biorefinery. Green Chem. 2013, 15, 860-871. (16) Gupta, P.; Singh, S. K.; Pathak, A.; Kundu, B. Template-directed approach to solid-phase combinatorial synthesis of furan-based libraries. Tetrahedron 2002, 58, 10469-10474.


24

Page 25 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(17) West, R. M.; Liu, Z. Y.; Peter, M.; Dumesic, J. A. Liquid Alkanes with Targeted Molecular Weights from Biomass-Derived Carbohydrates. ChemSusChem 2008, 1, 417-424. (18) 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. (19) Zhou, X.; Rauchfuss, T. B. Production of Hybrid Diesel Fuel Precursors from Carbohydrates and Petrochemicals Using Formic Acid as a Reactive Solvent. ChemSusChem 2013, 6, 383-388. (20) Cai, C. M.; Zhang, T.; Kumar, R.; Wyman, C. E. Integrated furfural production as a renewable fuel and chemical platform from lignocellulosic biomass.

J. Chem. Technol.

Biotechnol. 2014, 89, 2-10. (21) Siankevich, S.; Savoglidis, G.; Fei, Z.; Laurenczy, G.; Alexander, D. T. L.; Yan, N.; Dyson, P. J. A Novel Platinum Nanocatalyst for the Oxidation of 5-Hydroxymethylfurfural into 2,5-Furandicarboxylic Acid under Mild Conditions. J. Catal. 2014, 315, 67-64. (22) Dutta, S.; De, S.; Saha, B. A Brief Summary of the Synthesis of Polyester Building-Block Chemicals and Biofuels from 5-Hydroxymethylfurfural. ChemPlusChem 2012, 77, 259-272. (23) Nie, J.; Xie, J.; Liu, H. Efficient aerobic oxidation of 5-hydroxymethylfurfural to 2,5diformylfuran on supported Ru catalysts. J. Catal. 2013, 301, 83-91. (24) Ma, J.; Wang, M.; Du, Z.; Chen, C.; Gao, J.; Xu, J. Synthesis and properties of furanbased imine-linked porous organic frameworks. Polym. Chem. 2012, 3, 2346-2349.


25


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 33

(25) Moreau, C.; Belgacem, M.; Gandini, A. Recent Catalytic Advances in the Chemistry of Substituted Furans from Carbohydrates and in the Ensuing Polymers. Top. Catal. 2004, 27, 1130. (26) Bicker, M.; Hirth, J.; Vogel, H. Dehydration of fructose to 5-hydroxymethylfurfural in sub- and supercritical acetone. Green Chem. 2003, 5, 280-284. (27) Salak Asghari, F.; Yoshida, H. Acid-Catalyzed Production of 5-Hydroxymethyl Furfural from d-Fructose in Subcritical Water. Ind. Eng. Chem. Res. 2006, 45, 2163-2173. (28) Jiang, N.; Huang, R.; Qi, W.; Su, R.; He, Z. Effect of Formic Acid on Conversion of Fructose to 5-Hydroxymethylfurfural in Aqueous/Butanol Media. BioEnerg. Res. 2012, 5, 380386. (29) Siankevich, S.; Fei, Z.; Scopelliti, R.; Laurenczy, G.; Katsyuba, S.; Yan, N.; Dyson, P. J. Enhanced Conversion of Carbohydrates to the Platform Chemical 5-Hydroxymethylfurfural Using Designer Ionic Liquids. ChemSusChem 2014, 7, 1647-1654. (30) Zakrzewska, M. E.; Bogel-Łukasik, E.; Bogel-Łukasik, R. Ionic Liquid-Mediated Formation of 5-Hydroxymethylfurfural—A Promising Biomass-Derived Building Block. Chem. Rev. 2010, 111, 397-417. (31) Guo, X.; Cao, Q.; Jiang, Y.; Guan, J.; Wang, X.; Mu, X. Selective dehydration of fructose to 5-hydroxymethylfurfural catalyzed by mesoporous SBA-15-SO3H in ionic liquid BmimCl. Carbohydr. Res. 2012, 351, 35-41.


26

Page 27 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(32) Wang, H.; Kong, Q.; Wang, Y.; Deng, T.; Chen, C.; Hou, X.; Zhu, Y. Graphene Oxide Catalyzed Dehydration of Fructose into 5-Hydroxymethylfurfural with Isopropanol as Cosolvent. ChemCatChem 2014, 6, 728-732. (33) Yang, F.; Liu, Q.; Bai, X.; Du, Y. Conversion of biomass into 5-hydroxymethylfurfural using solid acid catalyst. Bioresour. Technol. 2011, 102, 3424-3429. (34) Chen, J.; Li, K.; Chen, L.; Liu, R.; Huang, X.; Ye, D. Conversion of fructose into 5hydroxymethylfurfural catalyzed by recyclable sulfonic acid-functionalized metal-organic frameworks. Green Chem. 2014, 16, 2490-2499. (35) Tian, C.; Zhu, X.; Chai, S.-H.; Wu, Z.; Binder, A.; Brown, S.; Li, L.; Luo, H.; Guo, Y.; Dai, S. Three-Phase Catalytic System of H2O, Ionic Liquid, and VOPO4–SiO2 Solid Acid for Conversion of Fructose to 5-Hydroxymethylfurfural. ChemSusChem 2014, 7, 1703-1709. (36) Nowak, I.; Ziolek, M. Niobium Compounds: Preparation, Characterization, and Application in Heterogeneous Catalysis. Chem. Rev. 1999, 99, 3603-3624. (37) Tanabe, K. Catalytic application of niobium compounds. Catal. Today 2003, 78, 65-77. (38) Ziolek, M. Niobium-containing catalysts—the state of the art. Catal. Today 2003, 78, 47-64. (39) Takagaki, A.; Sugisawa, M.; Lu, D.; Kondo, J. N.; Hara, M.; Domen, K.; Hayashi, S. Exfoliated Nanosheets as a New Strong Solid Acid Catalyst. J. Am. Chem. Soc. 2003, 125, 5479-5485.


27


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 33

(40) Carniti, P.; Gervasini, A.; Marzo, M. Absence of expected side-reactions in the dehydration reaction of fructose to HMF in water over niobic acid catalyst. Catal. Commun. 2011, 12, 1122-1126. (41) Nakajima, K.; Fukui, T.; Kato, H.; Kitano, M.; Kondo, J. N.; Hayashi, S.; Hara, M. Structure and Acid Catalysis of Mesoporous Nb2O5·nH2O. Chem. Mater. 2010, 22, 3332-3339. (42) Okumura, K.; Yamashita, K.; Hirano, M.; Niwa, M. The active and reusable catalysts in the benzylation of anisole derived from a heteropoly acid. J. Catal. 2005, 234, 300-307. (43) Li, C. C.; Dou, J.; Chen, L.; Lin, J.; Zeng, H. C. Antisolvent Precipitation for the Synthesis of Monodisperse Mesoporous Niobium Oxide Spheres as Highly Effective Solid Acid Catalysts. ChemCatChem 2012, 4, 1675-1682. (44) Luo, W.; Li, Y.; Dong, J.; Wei, J.; Xu, J.; Deng, Y.; Zhao, D. A Resol-Assisted CoAssembly Approach to Crystalline Mesoporous Niobia Spheres for Electrochemical Biosensing. Angew. Chem. Int. Ed. 2013, 52, 10505-10510. (45) Ghosh, S. C.; Li, C. C.; Zeng, H. C.; Ngiam, J. S. Y.; Seayad, A. M.; Chen, A. Mesoporous Niobium Oxide Spheres as an Effective Catalyst for the Transamidation of Primary Amides with Amines. Adv. Synth. Catal. 2014, 356, 475-484. (46) Wei, X.; Wang, Z.; Wu, Y.; Yu, Z.; Jin, J.; Wu, K. Fast pyrolysis of cellulose with solid acid catalysts for levoglucosenone. J. Anal. Appl. Pyrolysis 2014, 107, 150-154. (47) Holtzberg, F.; Reisman, A.; Berry, M.; Berkenblit, M. Chemistry of the Group VB Pentoxides. VI. The Polymorphism of Nb2O5. J. Am. Chem. Soc. 1957, 79, 2039-2043.


28

Page 29 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(48) Forghany, S. K. E.; Anderson, J. S. Reduction and polymorphic transformation of BNb2O5. J. Chem. Soc., Dalton Trans. 1981, 255-261. (49) Le Viet, A.; Jose, R.; Reddy, M. V.; Chowdari, B. V. R.; Ramakrishna, S. Nb2O5 Photoelectrodes for Dye-Sensitized Solar Cells: Choice of the Polymorph. J. Phys. Chem. C 2010, 114, 21795-21800. (50) Ko, E. I.; Weissman, J. G. Structures of niobium pentoxide and their implications on chemical behavior. Catal. Today 1990, 8, 27-36. (51) Michalkiewicz, B.; Sreńscek-Nazzal, J.; Tabero, P.; Grzmil, B.; Narkiewicz, U. Selective methane oxidation to formaldehyde using polymorphic T-, M-, and H-forms of niobium(V) oxide as catalysts. Chem. Pap. 2008, 62, 106-113. (52) Chai, S.-H.; Wang, H.-P.; Liang, Y.; Xu, B.-Q. Sustainable production of acrolein: Gasphase dehydration of glycerol over Nb2O5 catalyst. J. Catal. 2007, 250, 342-349. (53) Znad, H.; Kawase, Y. Synthesis and characterization of S-doped Degussa P25 with application in decolorization of Orange II dye as a model substrate. J. Mol. Catal. A: Chem. 2009, 314, 55-62. (54) Zhao, H.; Bennici, S.; Shen, J.; Auroux, A. The influence of the preparation method on the structural, acidic and redox properties of V2O5-TiO2/SO42− catalysts. Appl. Catal. A: Gen. 2009, 356, 121-128. (55) Appay, M.-D.; Manoli, J.-M.; Potvin, C.; Muhler, M.; Wild, U.; Pozdnyakova, O.; Paál, Z. High-resolution electron microscopic, spectroscopic, and catalytic studies of intentionally sulfided Pt/ZrO2–SO4 catalysts. J. Catal. 2004, 222, 419-428.


29


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 30 of 33

(56) Özer, N.; Chen, D.-G.; Lampert, C. M. Preparation and properties of spin-coated Nb2O5 films by the sol-gel process for electrochromic applications. Thin Solid Films 1996, 277, 162168. (57) Aufray, M.; Menuel, S.; Fort, Y.; Eschbach, J.; Rouxel, D.; Vincent, B. New Synthesis of Nanosized Niobium Oxides and Lithium Niobate Particles and Their Characterization by XPS Analysis. J. Nanosci. Nanotechno. 2009, 9, 4780-4785. (58) O'Neill, S. A.; Parkin, I. P.; Clark, R. J. H.; Mills, A.; Elliott, N. Atmospheric pressure chemical vapour deposition of thin films of Nb2O5 on glass. J. Mater. Chem. 2003, 13, 29522956. (59) García-Sancho, C.; Moreno-Tost, R.; Mérida-Robles, J. M.; Santamaría-González, J.; Jiménez-López, A.; Maireles-Torres, P. Niobium-containing MCM-41 silica catalysts for biodiesel production. Appl. Catal. B: Environ. 2011, 108–109, 161-167. (60) Wang, F.; Wu, H.-Z.; Liu, C.-L.; Yang, R.-Z.; Dong, W.-S. Catalytic dehydration of fructose to 5-hydroxymethylfurfural over Nb2O5 catalyst in organic solvent. Carbohydr. Res. 2013, 368, 78-83. (61) Denofre, S.; Gushikem, Y.; de Castro, S. C.; Kawano, Y. Stability and surface acidity of niobium(V) oxide grafted on a silica gel surface. J. Chem. Soc., Faraday Trans. 1993, 89, 1057-1061. (62) Wang, Y.; Tong, X.; Yan, Y.; Xue, S.; Zhang, Y. Efficient and selective conversion of hexose to 5-hydroxymethylfurfural with tin–zirconium-containing heterogeneous catalysts. Catal. Commun. 2014, 50, 38-43.


30

Page 31 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(63) Huang, Z.; Pan, W.; Zhou, H.; Qin, F.; Xu, H.; Shen, W. Nafion-Resin-Modified Mesocellular Silica Foam Catalyst for 5-Hydroxymethylfurfural Production from D-Fructose. ChemSusChem 2013, 6, 1063-1069. (64) Qi, X.; Watanabe, M.; Aida, T. M.; L. Smith Jr, R. Sulfated zirconia as a solid acid catalyst for the dehydration of fructose to 5-hydroxymethylfurfural. Catal. Commun. 2009, 10, 1771-1775. (65) Qi, X.; Guo, H.; Li, L. Efficient Conversion of Fructose to 5-Hydroxymethylfurfural Catalyzed by Sulfated Zirconia in Ionic Liquids. Ind. Eng. Chem. Res. 2011, 50, 7985-7989. (66) 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. (67) Crisci, A. J.; Tucker, M. H.; Lee, M.-Y.; Jang, S. G.; Dumesic, J. A.; Scott, S. L. AcidFunctionalized SBA-15-Type Silica Catalysts for Carbohydrate Dehydration. ACS Catal. 2011, 1, 719-728. (68) Zhao, Q.; Wang, L.; Zhao, S.; Wang, X.; Wang, S. High selective production of 5hydroymethylfurfural from fructose by a solid heteropolyacid catalyst. Fuel 2011, 90, 22892293. (69) Liu, X.-Y.; Huang, M.; Ma, H.-L.; Zhang, Z.-Q.; Gao, J.-M.; Zhu, Y.-L.; Han, X.-J.; Guo, X.-Y. Preparation of a Carbon-Based Solid Acid Catalyst by Sulfonating Activated Carbon in a Chemical Reduction Process. Molecules 2010, 15, 7188-7196.


31


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Page 32 of 33

(70) Lee, Y.-Y.; Wu, K. C. W. Conversion and kinetics study of fructose-to-5hydroxymethylfurfural (HMF) using sulfonic and ionic liquid groups bi-functionalized mesoporous silica nanoparticles as recyclable solid catalysts in DMSO systems. Phys. Chem. Chem. Phys. 2012, 14, 13914-13917. (71) Román-Leshkov, Y.; Dumesic, J. Solvent Effects on Fructose Dehydration to 5Hydroxymethylfurfural in Biphasic Systems Saturated with Inorganic Salts. Top. Catal. 2009, 52, 297-303. (72) Musau, R. M.; Munavu, R. M. The preparation of 5-hydroxymethyl-2-furaldehyde (HMF) from d-fructose in the presence of DMSO. Biomass 1987, 13, 67-74.


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