Macroporous Niobium Phosphate-Supported Magnesia Catalysts for

Subscriber access provided by University of South Dakota

Article

Macroporous niobium phosphate-supported magnesia catalysts for isomerization of glucose-to-fructose Da-Ming Gao, Yong-Bing Shen, Bohan Zhao, Qian Liu, Kazuki Nakanishi, Jie Chen, Kazuyoshi Kanamori, Huaping Wu, Zhiyong He, Maomao Zeng, and Haichao Liu ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.9b00292 • Publication Date (Web): 21 Mar 2019 Downloaded from http://pubs.acs.org on March 24, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 47 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

ACS Sustainable Chemistry & Engineering

Macroporous niobium phosphate-supported magnesia catalysts for isomerization of glucose-to-fructose

Da-Ming Gao1*, Yong-Bing Shen2, Bohan Zhao3, Qian Liu1, Kazuki Nakanishi4, Jie Chen1, Kazuyoshi Kanamori4, Huaping Wu5, Zhiyong He1, Maomao Zeng1, Haichao Liu3*

1

State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China

2

Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Sendai 980-8578, Japan

3

Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China

4

Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan

5

Key Laboratory of Special Purpose Equipment and Advanced Manufacturing

Technology, Zhejiang University of Technology, Ministry of Education and Zhejiang Province, Hangzhou 310014, China

* Corresponding authors. Tel.: +86 51085329032; Fax: +86 51085919069. 1

ACS Paragon Plus Environment

ACS Sustainable Chemistry & Engineering 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

E-mail: [email protected] (Da-Ming Gao),

[email protected] (Haichao Liu)

Keywords: Glucose; isomerization; supported magnesia; fructose; niobium phosphate; hierarchically porous material.

Abstract The catalytic performance of hierarchically porous niobium phosphate (NbP) supported magnesia for the glucose isomerization to fructose, was investigated under atmospheric air atmosphere. Porous NbP showed improved support effects on MgO in comparison to other metal oxides tested for glucose isomerization. Also, the amount and distribution of basic sites were largely changed by supporting magnesia on NbP. Although the textural properties were reduced and solid acids formed on the MgO/NbP catalysts, glucose isomerization was promoted by increasing magnesium content. The maximum yield of fructose reached ca. 24.6% over 40%MgO/NbP-500 with selectivity of 65.7% for 1.0 wt.% glucose at 120 °C. The fructose productivity peaked as high as 13.6 g gcatalyst‒1 h‒1 over 40%MgO/NbP-700 catalyst. The leaching of cations and anions resulted in a homogeneous system for glucose isomerization. Regeneration almost fully reactivated the catalyst to its initial activity. The MgO/NbP showed high stability under air atmosphere for 15 days, and high potential use for glucose isomerization. 2


Page 2 of 47

Page 3 of 47 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


INTRODUCTION Sustainable development urgently requires new energy matrices and novel synthetic material resources in view of the diminishing fossil resources. Utilization of biomass has been considerably boosted, giving its CO2 neutrality and renewable character.1 Lignocellulosic biomass, including cellulose, hemicellulose, and lignin, consists of major biomass components of appreciable potential usages.2‒8 Cellulose, in particular, as the main component of lignocellulosic biomass, has been already converted to many valuable products, from industrial intermediates to final products.9‒ 13

Effective conversion of cellulose under catalytic process often undergoes hydrolysis

to glucose, isomerization of glucose to fructose, and further reactions of fructose to other products such as hydroxymethylfurfural (HMF). Success in isomerization of glucose to fructose can significantly improve the utilization of cellulose and reduce the energy consumption.14,15

The isomerization of glucose to fructose can be carried out by enzymatic and chemical methods.16‒21 The enzymatic catalysis affords a nearly thermodynamic equilibrium yield of fructose with a small amount of mannose as byproduct. Several disadvantages of this process, such as tedious purification of substrate and irreversible deactivation of the enzyme restrict its application in the biomass conversion. Homogeneous catalysis is often corrosive and generate large amount of by-products, which inhibited its practical use.21‒29 3



Solid catalysts are, on the other hand, more practical when compared to enzymes and homogeneous catalysts, due to their wide range of operating temperatures, and ease of separation and recovery. It has been reported that solid acidic oxides and phosphates of transition metals, such as titanium and niobium, exhibit strong Lewis acidity for isomerize of glucose into fructose.30‒32 Sn-β-zeolite can isomerize glucose to fructose in a high yield of ca. 30% in aqueous solutions.28,33 Alcoholysis have been employed to shift the chemical equilibrium of glucose isomerization to increase the fructose, as exemplified by methanolysis over H-USY, Al-BEA, and Sn-SPP catalysts.34‒36 However, some problems such as low yield, sluggish synthesis of the catalysts, low solubility of substrate, or high catalyst loading significantly restrict their practical application.

Alternatively, solid bases have been investigated as green catalysts for the production of fructose and other ketoses.23,37‒40 For example, anion-echange resins can afford high fructose yields of 72% and have been also used to synthesize some rare ketoses, such as tagatose and psicose.41 Nonetheless, the use of resins encounters problems associated with their poor thermal stability and recyclability. Solid basic metal oxides, which are thermally stable and can be easily regenerated by calcination, can catalyze the isomerization of glucose, thus attracting much attention.23,38‒40 The most extensively studied solid bases for glucose isomerization in aqueous phase include hydrotalcites, zirconium oxide, alkaline ion-exchanged zeolites, and MgO. 4


Page 4 of 47

Page 5 of 47 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


Hydrotalcites and ZrO2-based solid base were also limited in practical use due to their low activity, low selectivity, or harsh reaction condition. Among the ion-exchanged zeolites reported, KA and CsA zeolites exhibited high performance for glucose isomerization with fructose yields of 21% and 23%, respectively. However, leaching of Mg ion and destroy of the structure of the zeolites lead to the deactivation of the catalysts, which limits their practical application.

MgO, however, a nontoxic solid base with high intrinsic basicity, can isomerize glucose to fructose in water without the necessity of inert gas protection.42−44 Marianou et al. have reported fructose production with yields between ca. 26 and 33% as well as high selectivity, by using doped-MgO catalysts.43,44 It was also illustrated that the strong basicity of MgO promotes side reactions leading to low selectivity of fructose.43‒47 Moreover, MgO tends to rehydrate at its surface and surfer leaching of Mg2+ in the aqueous reaction solutions, leading to its low reaction efficiency.48‒50

Recently, the catalytic performance of MgO was improved by anchoring on Nazeolites.51,52 Still, the reaction had to undergo N2 purging and the leaching of Mg2+ was not effectively inhibited. Such leaching problem might be addressed by effective condensation reaction of hydroxyl groups between MgO and its support. In a previous work, we have synthesized a hierarchically porous niobium phosphate (NbP)-based monoliths through a sol-gel process accompanied by phase separation.53 Such NbP sample is amorphous, and retains large amounts of hydroxyl groups with a high 5



specific surface area (~140 m2·g‒1) even after calcination at 600 ºC. In addition this macroporous co-continuous material has low back pressure when used in packed bed for flow reaction. Herein, we use such high-area NbP support to prepare the MgO catalysts (MgO/NbP) for the isomerization of glucose to fructose. We characterize the crystal growth, distribution of basic sites, change in microstructure, and chemical bond formation of the MgO/NbP catalyst, aiming to understand the supporting effects on the surface properties of MgO. The MgO activities on different supports are also compared under different experimental conditions. It is found that the MgO/NbP catalysts show high stability during the glucose isomerization reaction in water and air atmosphere.

EXPERIMENTAL SECTION Materials

Ammonium niobium oxalate hydrate (NH4-Nb) as niobium precursor, concentrated phosphoric acid (>85 wt.% in water), polyacrylamide (PAAm, Mw = 1.0 × 104), poly(ethylene glycol) (PEO, Mw = 3.5 × 104) and citric acid were all purchased from Sigma-Aldrich Co. USA. Glucose, fructose, mannose, niobium(V) oxide, silica, alumina, titania, zirconia, magnesium nitrate hexahydrate, 28 wt.% ammonia solution

6


Page 6 of 47

Page 7 of 47 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


and 35 wt.% aqueous hydrogen peroxide (H2O2) were purchased from Sinopharm Chemical Reagent Co., Ltd., Shanghai, China.

Synthesis of the monolithic co-continuous macroporous NbP The monolithic NbP was synthesized by our previous reported method.53 Briefly, NH4-Nb and citric acid were dispersed in H2O2 and digested at 80 °C until the hydrogen peroxide was completely decomposed. The phase separation inducers, PAAm and PEO, were dissolved at 25 °C. Finally, the concentrated phosphoric acid was added under vigorous stirring for ca. 3 min and the resultant solution was allowed to gel.

After gelation and aging for 24 h, the wet gel was subjected to solvent-exchanges at room temperature using methanol, 40 vol.% hexane in methanol, and pure hexane for 12 h, respectively. The resultant gel was vacuum-dried to obtain crack-free niobium phosphate monolith. The obtained NbP monolith was further calcined at 600 °C for 8 h and crashed for using as catalyst support.

Synthesis of MgO/support samples

7



Page 8 of 47

The supported MgO catalysts with different MgO content (10–60 wt.%, weight ratio of MgO to each support) on different inorganic oxide supports were prepared by impregnating

each

support

with

aqueous

magnesium

nitrate

hexahydrate

(Mg(NO3)2·6H2O). Typically, for 10%MgO/NbP catalysts, 1.0 g of the crashed NbP powder was firstly dispersed in water. Then, 0.69 g of the Mg salt was added under vigorous stirring for ca. 12 h. After that, samples were dried at 120 °C overnight, and finally calcined at 500–1000 °C for 5 h. The obtained samples were respectively denoted as XMgO/NbP-Y, where X was the weight ratio of MgO to porous NbP, and Y was the pretreatment temperature.

Bulk magnesium oxide was prepared by precipitating magnesium nitrate hexahydrate using 28 wt.% ammonia solution at room temperature. After precipitating, MgO was washed with water and ethanol until the pH reached ca. 7.5. The resulting wet MgO gel was then calcined at the predetermined temperatures.

All the supported and non-supported MgO were immediately used after preparation to avoid deactivation in air, and the commercial MgO sample was precalcined at 500 °C for 2 h prior to use.

Characterization

8


Page 9 of 47 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


Morphology of the dried NbP gel was observed using a scanning electron microscope (SEM: JSM-6060S, JEOL, Ltd., Japan, with Pt coating). The crystal structure was confirmed by using powder X-ray diffraction (XRD, RINT Ultima III, Rigaku Co., Japan) with Cu Kα (λ = 0.154 nm) as incident beam. Mesopore size distributions were calculated from the adsorption branch of the N2 sorption isotherm, using the BJH (Barrett-Joyner-Halenda) method. The temperature‒programmed‒desorption of carbon dioxide (CO2-TPD) was measured on a TP-5080 (Tianjin Xianquan, China) flow unit to evaluate the total basicity of the MgO/NbP samples. Before the CO2-TPD measurements, the samples were preheated at 500 °C for 1 h in helium gas (30 mL·min–1). After the sample was cooled to 50 °C, CO2 adsorption was performed at CO2 pressure of 0.15 MPa for 15 min. Then, the gas phase and physically adsorbed CO2 was purged by helium gas (30 mL·min–1) for 1 h at the same temperature. The sample was then heated at a constant rate of 10 °C·min–1 from 50 to 800 °C under helium flow at 30 mL·min–1.

The structure of CO2 chemisorbed on the supported MgO surface was determined by infrared spectroscopy (IR). The experiments were carried out using an inverted Tshaped cell containing a MgO/NbP sample pellet fitted with CaF2 windows. Data were obtained using a Bruker Tensor 27 spectrophotometer after CO2 adsorption at 25, 100, 200, and 300 °C. Spectra were taken at 25 °C after desorption at each

9



predetermined temperature. The absorbance scales were normalized to 30-mg pellets for comparison.

Transmission electron microscopy (TEM) was carried out by using a JEM-2100 Transmission Electron Microscope (JEOL, Ltd., Japan), operating at 200 kV. The samples were prepared by uniformly dispersing MgO/NbP in ethanol and then placing on the carbon-coated grids.

The coke deposition on the catalyst surface was analyzed by using thermogravimetric analysis (TGA, TGA/SDTA851e, Mettler Toledo, Sweden). The samples were heated up from room temperature to 800 °C, at 5 °C·min–1., under oxygen gas flow of 20 mL·min–1.

Catalytic reactions

Isomerization of glucose at various reaction conditions was performed to investigate the catalytic performance of the supported MgO catalysts. The initial concentration of glucose was adjusted to be in the range 1.0–20.0 wt.%. The reactions were carried out in a 15 mL glass reactor containing a small magnetic stirring bar. The glass reactor was sealed, using a crimp top and was placed in a temperature-controlled silicone oil bath. After reaction, the glass reactor was immediately put into a water

10


Page 10 of 47

Page 11 of 47 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


bath to quench the reaction. The catalyst loading was set to be 0.0025–0.02 g·gsolution–1. The catalysts were regenerated by calcination at 600 °C for 4 h.

In order to analyze the components after reaction, the reactant was centrifuged at 10,000 rpm for 15 min, removed using a syringe, and filtered using a 0.45 μm filter into an HPLC vial for analysis. The compositional analysis was performed on an HPLC system, equipped with RI refractometer and UV detector with an Agilent HiPlex Ca column (7.7 mm I.D. × 300 mm length, Agilent Technologies, Germany). The HPLC chromatogram of glucose, mannose, fructose and reactant of glucose with 40%MgO/NbP-500 catalyst was provided in Fig. S1. The productivity of fructose was defined that the weight amount of fructose produced from 1 kg solution of glucose per hour.

Leaching of cations from the catalysts to the reaction mixture was measured, using a Perkin-Elmer Optimal 2000 DV inductively coupled plasma (ICP) system (NexION 350, Perkin-Elmer, USA).

RESULT AND DISCUSSION Catalyst characterization

The detailed characterization of the NbP sample was reported in our previous work.53 Figure S2 briefly shows the SEM images, XRD patterns, and N2 adsorption‒ 11



desorption isotherms of the as-dried and calcined NbP samples. The co-continuous macroporous NbP was synthesized by sol‒gel method accompanied with phase separation in the presence of both PAAm and PEO as phase separation inducers, and crack-free monolith were obtained after drying in vacuum. The as-dried NbP sample exhibited low crystallinity as shown by the broad and weak diffraction peaks, and then turned to amorphous structure, and α-NbOPO4 crystalline phase after calcined at 600 °C and 1000 °C for 8 h, respectively. The as-dried NbP sample had low BET surface area and then increased to ca. 140 m2·g–1 after calcining at 600 °C for 8 h, due to the formation of mesopores, ranging from 4 to 10 nm with average pore size of 9 nm and micro/mesopore volume as 0.33 cm3·g–1. Higher temperature-treatment resulted in much lower specific surface areas, such as 5 m2·g–1, for the sample after heat treatment at 800 °C.

The powder XRD diffractogram of MgO/NbP-500 catalysts with various MgO content, were shown in Fig. 1. Clearly, MgO was highly dispersed on the NbP surface particularly for 20%MgO/NbP-500 catalyst. The absence of the characteristic peaks of NbP crystal indicates that phase transformation of NbP samples did not occur during preparation of MgO/NbP-500 catalysts. A weak peak corresponding to the (111) plane of MgO crystal was detected for the MgO contents in the range of 20‒60 wt.%. A peak corresponding to the (200) plane was detected when MgO content exceeded 40 wt.%, indicating preferential growth of (111) plane in comparison to the 12


Page 12 of 47

Page 13 of 47 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


(200) plane of MgO on the NbP surface. However, when MgO loading exceeded 40 wt.%, the growth of the (200) plane was enhanced on the NbP surface, similarly to pure MgO growth. These observations indicate that the growth of MgO was influenced by the underlying NbP when the loading amount was small, and isotropic growth was enhanced when the loading amount became higher. It can also be confirmed from the TEM micrographs that the mesopores in the macropore skeletons were fully filled and that the MgO crystals began to grow on the outermost surface of the skeletons of NbP with larger particle size (Fig. S3). The MgO growth was different from that of magnesium-impregnated zeolites, in which MgO was not identified by XRD analysis, due to the small size or the amorphous structure.51 Large mesopores in the NbP samples allow the growth of the magnesia crystals, therefore enabling their detection by XRD. Besides, a peak of Nb2O5 (2θ = 76.4°) was also found, implying ion exchange or leaching of Nb during the catalyst preparation.

The dependence of texture properties on MgO content and calcination temperature was investigated by using N2 adsorption-desorption measurements, and the results are summarized in Table 1. Increasing MgO content decreased the BET surface areas and mesoporous volumes of the MgO/NbP samples. Impregnating NbP with 20 wt.% MgO did not significantly change the textural properties, i.e., SBET decreased by only ca. 7.2% compared with the NbP sample without impregnation. However, when MgO content was increased above 30 wt.%, SBET decreased by ca. 13



40%‒84%. Likewise, changes of mesoporous volumes (see Vp, Table 1) were observed. The mesopores persisted after incorporating 20 wt.% of MgO, although sizes (Dp) slightly changed from 9 nm to 7 nm.

The amount and strength distribution of basic sites on the NbP supported MgO catalysts were measured by CO2-TPD, and compared with those of pure MgO catalysts. Fig. 2 shows the typical CO2-TPD profiles of pure MgO and MgO/NbP-500 catalysts with 20‒60 wt.% MgO loading. Basic sites were not identified on the NbP surface by CO2-TPD. The strength of basic sites was classified according to the desorption temperature of the adsorbed CO2. Most of the desorption of CO2 on pure MgO-500 was in the temperature range of 180–450 °C, likely due to the strong basic sites and small amount of intermediate basic sites. However, the MgO/NbP-500 catalysts revealed the presence of weak and intermediate basic sites, as confirmed by the lower desorption temperatures assigned to a small amount of strong basic sites. In particular, weak basic sites were dominant for 20–40 wt.% MgO samples; meanwhile, a gradual increment of intermediate and strong basic sites are observed when MgO contents were incremented to 50 wt.% and 60 wt.%.

Fig. 3 typically shows the FT-IR spectra of MgO, 40%MgO/NbP-500, and 40%MgO/NbP-700 after adsorption of CO2 at 25 °C and sequential desorption at 100, 200, and 300 °C to illustrate the structure of CO2 chemisorbed on the catalyst surfaces. Cosimo, Iglesia, and Belin et al. demonstrated that CO2 was adsorbed on the surface 14


Page 14 of 47

Page 15 of 47 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


of MgO mainly through bicarbonate, bidentate, and unidentate carbonates species, which refer to the low-, medium-, and high-strength basic sites, respectively.53‒57 The formation of bicarbonates requires the presence of hydroxyl groups on the MgO surface, which exhibit a C‒OH bending mode at ca. 1220 cm‒1 as well as asymmetric and symmetric O‒C‒O stretching modes at ca.1650 and 1480 cm‒1, respectively. Formation of bidentate and unidentate carbonates were both attributed to the presence of surface basic oxygen atoms (low-coordinated oxygen anions). Bidentate carbonates exhibit sharp symmetric and asymmetric O‒C‒O stretching modes, at ca. 1320‒1340 cm‒1 and 1610‒1630 cm‒1, respectively. Unidentate carbonates show symmetric and asymmetric stretching of O‒C‒O at ca. 1360‒1400 cm‒1 and 1510‒1560 cm‒1, respectively. Accordingly to the FT-IR spectra of MgO and 40%MgO/NbP-500 samples, it was also clearly shown that the distribution of basic sites was shifted to the medium-strength ones after supporting MgO on NbP sample.

By elevating the pretreatment temperature of the MgO and MgO/NbP catalysts to 700 °C, significant changes on the amount and distribution of basic sites were observed (Fig. 2b and Fig. 3a). Multiple strong basic sites on MgO-700 were generated. Considering the MgO/NbP-700 catalysts, the desorption bands peaked at 260‒280 °C were smaller as compared with those of MgO/NbP-500 sample. The proportion of peaks at ca. 135 °C decreased, whereas weak basic sites peaked at 85 °C, and additional features at high temperatures emerged. The presence of strong basic 15



sites on MgO/NbP-700 surface may be ascribed to the inhibition of the rearrangement of MgO on the NbP surface by the formation of chemical bonding between MgO and NbP, as a new phase of Mg3(PO4)2 was detected by XRD analysis, which will be discussed later in this paper. Further, Fig. 3 also shows that the intensities of all the bands decreased with increasing evacuation temperature. In particular, bands assigned to the medium-strength basic sites decreased more quickly than those assigned to the high-strength ones. It was realized that only unidentate carbonate bands remained after evacuation at or above 100 °C for MgO-500 and it is not the case for the NbP supported MgO. Altogether these results reinforce the idea that MgO basicity is significantly altered by using NbP as support.

Effect of support on isomerization of glucose

Isomerization of glucose over different metal oxides supported MgO catalysts (40 wt.% of MgO), was conducted to probe support effects on the parameters listed in Table 2. The isomerization of glucose over pure MgO was also performed for comparison. In contrast to high glucose conversions, MgO afford significantly low fructose yield and selectivity, reaching 65.1% conversion with 16.4% of fructose yield and 25.2% of selectivity at 90 °C. The reaction efficiency decayed with increasing the reaction temperature to 120 °C, even at a shorter reaction time. The low efficiency of the reaction may be due to the decomposition of monosaccharides, as suggested by 16


Page 16 of 47

Page 17 of 47 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


the dark brown color of the reaction solution after the experiment. This also implies that strong basicity is not desirable for isomerization of glucose in aqueous conditions. Meanwhile, niobium oxide and the other oxides tested as support, also improved the yield and selectivity of fructose comparing with pure MgO; particularly, Al2O3 provided the fructose yield as high as 28.1%. However, comparing the NbP support, the tested oxides afford relatively lower selectivity of fructose and total sugar yield. These results clearly confirm NbP as a suitable support for MgO, in order to maintain its reactivity and improve its selectivity towards glucose isomerization in aqueous solution.

Effect of MgO content and reaction temperature on isomerization of glucose

The catalytic performance of MgO/NbP depends on its MgO content in the glucose-to-fructose isomerization. Fig. 4 shows the evolution of glucose isomerization over MgO/NbP-500 as a function of the MgO content. As expected, fructose was not detected in the absence of MgO in the catalyst at 120 °C. It was realized that the conversion is only ca. 1.0% after reacting glucose with NbP at 120 °C for 60 min with ca. 0.1% (mol/mol) HMF as side-product. Glucose was converted faster by increasing the MgO content. Fructose was the dominant product with 50% of fructose was produced from 10.0 wt.% glucose via a homogeneous reaction.50,52 This difference may be attributed to the Na+ and Mg2+ leached from the MgO/NaY zeolite catalyst (582 ppm Na+, 7.9 ppm Mg2+), claimed to have synergistically catalyzed the glucose isomerization.

Dependence of fructose productivity on the initial glucose concentration

Dependence of fructose productivity on the initial glucose concentration was investigated in the glucose concentration range of 1.0‒20.0 wt.% over 40%MgO/NbP700 at 120 °C (Table 4). The conversion of glucose and yield of fructose decreased 22


Page 22 of 47

Page 23 of 47 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


with increasing initial concentrations. As an example, when the initial concentration was increased from 1.0 wt.% to 10.0 wt.% and 20.0 wt.%, the conversion of glucose decreased by ca. 18.8% and 30.2% with the yield of fructose decreased by 2.7% and 10.7%, respectively, at the residence time of 30 min. The results suggest no linear correlation between initial concentration and fructose selectivity. Analogous behavior was also observed when analyzing the total yield of sugars in solution after the reaction time of 30 min.

In terms of productivity of fructose, calculated at the time of 30 min, significant improvement was observed at higher glucose concentrations. An eleven-fold increment (from 4.2 g·kg-solution‒1·h‒1 to 44.3 g·kg-solution‒1·h‒1) was obtained upon the increment of glucose concentration from 1.0 wt.% to 20.0 wt.%. On the other hand, the selectivity of mannose kept lower than 7.0% (yields lower than 2.5%) under even higher reaction times ( up to 4 h), indicated that the formation of mannose was not thermodynamically favorable.

Potential practical application

Effect of the catalyst loading was assessed to further investigate the MgO/NbP catalyst activity in the 40%MgO/NbP-700 to glucose ratio (wt/wt) ranging from 1/40 to 1/5 in 10.0 wt.% glucose solution. According to the results shown in Fig. S5, the 23



amount of catalyst slightly affected the isomerization process of glucose. Glucose conversion only slightly decreased, whereas fructose yields decreased by ca. 1.0% for the catalyst loadings of 1/40 and 1/5. Low reaction efficiency at high catalyst loading such as 1:5 (0.02 g·g-solution‒1), can be attributed to the simultaneous decomposition of the monosaccharides promoted by MgO/NbP. With respect to the yield and selectivity of fructose, the optimal catalyst loading was found to be 40/1–10/1.

The reuse of 40%MgO/NbP-700 was investigated in 10.0 wt.% glucose solution with a catalyst loading of 0.01g·g-solution‒1 at 120 °C and 30 min of reaction time (Fig. 6). When the 40%MgO/NbP catalyst was used without regeneration, deposition of carbonaceous materials on the catalyst surface and leaching of Mg2+ ions during the reaction led to deactivation of the catalyst with increasing numbers of reaction runs. Large decrease in glucose conversion and fructose yield was observed after the first run, likely due to the leaching of Mg2+, as shown in Table 3. It can be also seen from the XRD pattern of the 40%MgO/NbP-700 after regeneration that the intensity of MgO was decreased and those of solid acids increased, in particularly for Mg3(PO4)2. The selectivity of fructose was increased by >20% despite the low activity. Moreover, a relative stabilization of the activity was observed after the second run, at ca. 14.1% to 11.7% for the conversion of glucose from the second to third run without significant change in the selectivity of fructose. When regeneration by thermal treatment was applied to the 40%MgO/NbP-700 catalyst after first and second runs, 24


Page 24 of 47

Page 25 of 47 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


the original catalyst performance was almost fully recovered. This indicates that the 40%MgO/NbP-700 catalyst can be used for at least three times. Loss of stability during reaction can be attributed to the leaching of ions and deposition of coke, since it was observed that coke deposition reached ca. 2.9‒4.1 wt.% (Table 3). Again, NbP supported MgO was less susceptible to coke deposition than pure MgO. These experimental results show that NbP can significantly affect the surface properties of MgO, as also confirmed by the CO2-TPD profiles.

The catalytic performance of MgO/NbP on the isomerization of glucose was compared with those of other solid bases and Ti/Sn-β-zeolites, previously reported in the literature (Table 5). This comparison considered the reaction condition, as well as glucose conversion, fructose yield, fructose selectivity, and catalyst efficiency. Here, the catalyst efficiency was defined as the amount of fructose produced over 1.0 g catalyst per hour at certain reaction conditions. The exact values of the loading of Ti/Sn-β-zeolites were not given in the reported literature; however, the molar ratio of glucose to metal was exactly known. Therefore, the Ti/Sn-β-zeolites loadings were estimated using the molecular weight of SiO2, since the content of Ti or Sn was small in these two zeolites (Ti/Sn:Si ≈ 1:100). It can be seen that the 40%MgO/NbP-700 catalyst has similar, if not superior, efficiency compared to other solid bases. It showed suboptimal values if compared to Ti/Sn-β-zeolites in terms of catalyst efficiency but higher fructose selectivity. 25



CONCLUSIONS The surface properties of MgO, including the amount and distribution of basic sites and resistance to water, were significantly changed by supporting on the synthesized porous niobium phosphate. The MgO/NbP showed improved catalytic performance towards glucose to fructose isomerization at 100‒120 °C. The selectivity of fructose was found to be as high as 65.5% with yield of 18.1% from 10.0 wt.% glucose, in clear contrast to the case of the same reaction carried out over pure MgO. Increasing the pretreatment temperature also enhanced the water tolerance of MgO/NbP. The efficiency of the 40%MgO/NbP-700 catalyst reached as high as 13.6 gfructose·gcatalyst‒ 1

·h‒1 at 120 °C. Overall, the herein synthesized porous NbP showed better support

effects for MgO than other typical inorganic oxides, and the prepared MgO/NbP catalysts demonstrated to be promising solid bases for glucose isomerization to fructose.

26


Page 26 of 47

Page 27 of 47 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


(f)

MgO

Nb2O5

Mg3(PO4)2

Nb1.91P2.82O13

NbOPO4

Nb(P2.02O7)

(e) (d)

(c) (b)

（200）

(a)

（220）

（111）

10

20

30

40

50

60

70

Diffraction angle, 2θ°

Figure 1. XRD patterns of (a) pure MgO prepared by precipitation and calcined at 500 °C, (b) 20%MgO/NbP-500, (c) 40%MgO/NbP-500, (d) 60%MgO/NbP-500, (e) 40%MgO/NbP-700, and (f) 40%MgO/NbP-700 after regeneration.

27



(a)

Intensity

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 47

MgO 20%MgO/NbP 30%MgO/NbP

(b)

intensity × 3

40%MgO/NbP 50%MgO/NbP 60%MgO/NbP

0

200

400

600

Temperature (ºC)

Figure 2. Typical CO2-TPD profiles for MgO/NbP samples with 20‒60 wt.% MgO contents respectively calcined at (a) 500 °C and (b) 700 °C.

28


Page 29 of 47 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


(a)

intensity × 20

(I)

(II) (III) (IV)

(b)

intensity × 4

(I) (II) (III) (IV)

(c)

(I) (II) (III) (IV)

1800

1600

1400

1200

ν (cm-1) Figure 3. IR spectra of CO2 adsorbed on (a) 40%MgO/NbP-700, (b) 40%MgO/NbP500, (c) MgO-500 samples upon increasing evacuation temperatures: (I) 25 °C, (II) 100 °C, (III) 200 °C, and (IV) 300 °C. 29



80

Conversion of glucose, Yield of fructose, Selectivity of fructose (wt%)

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 47

60

40

20

0 20

30

40

50

60

MgO content (wt%, MgO/NbP)

Figure 4. Effect of MgO content in MgO/NbP-500 on glucose isomerization at 120 °C with the catalyst loading of 0.01g g-solution‒1. The initial glucose concentration was 1.0 wt.% and the data were obtained when the maximum yield of fructose reached. (■)glucose conversion, ( ) yield of fructose, and (□) selectivity of fructose. 30


Page 31 of 47

100


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


80

60

40

20

0 500

600

650

700

750

1000

Calcination temperature (ºC)

Figure 5. Effect of calcination temperature on activity of 40%MgO/NbP for glucose isomerization with the reaction time of 30 min. The initial glucose concentration was 10.0 wt.% with the catalyst loading of 0.01 g/g-solution. The symbols were the same as in Fig. 4.

31



100


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 32 of 47

80

60

40

20

0 Run 1

Run 2

Run 3

Without regeneration

Run 1

Run 2

With regeneration

Figure 6. Comparison of glucose isomerization over 40%MgO/NbP-700 after consecutive reactions with and without regeneration at 120 °C after 30 min. The initial glucose concentration was 10.0 wt.% with the catalyst loading of 0.01g/gsolution. The symbols were the same as in Fig. 4. 32


Page 33 of 47 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


Table 1 Textural properties, CO2 adsorption capacity and catalytic performance of catalysts with various MgO contents, calcined at different temperatures. Calcination

Basic site

SBET

TONa

Vp

Dp

CO2

(cm3/g)

(nm)

(μmol/g)

(ºC)

（m2/g ）

NbP

600

140

0.33

9

–

–

‒

MgO

500

8.7

0.09

42

2255

259

0.40b

20%MgO/NbP

500

130

0.28

7

4986

38

0.12

30%MgO/NbP

500

85

0.16

67

4704

55

0.23b

40%MgO/NbP

500

41

0.15

–

2656

65

0.51b

Catalyst

Temp.

density (μmol/m2)

(mol/mol)

b

(2.92c) 50%MgO/NbP

500

28

0.14

–

2761

98

0.47 b

60%MgO/NbP

500

22

0.12

–

2666

121

0.45b

MgO

700

0.4

–

–

857

2141

‒

20%MgO/NbP

700

14

0.054

–

537

38

‒

30%MgO/NbP

700

7

–

–

687

98

‒

40%MgO/NbP

700

4

0.06

–

704

176

1.85b (14.20c)

50%MgO/NbP

700

4

0.04

–

1053

263

‒

60%MgO/NbP

700

8

0.08

–

870

109

‒

a: the TON value was calculated with respect to the maximum yield of fructose. b: the initial concentration of glucose was 1.0 wt.%. c: the initial concentration of glucose was 10.0 wt.%. 33



Page 34 of 47

Table 2 Support effects on MgO performance for the isomerization of glucose.

Temp. Support (ºC) MgO

Glc

Fru

Fru

Man

Total

conversion

yield

(%)

(%)

(%)

(%)

(%)

Time selectivity selectivity sugar yield

(min)

90

60

65.1

16.4

25.2

3.9

53.8

120

30

81.0

17.4

21.6

0

36.4

NbP

120

30

35.3

24.6

69.7

6.6

91.6

Nb2O5

120

30

76.7

20.4

26.7

7.4

49.4

Al2O3

120

30

59.5

27.1

45.6

6.9

71.7

TiO2

120

30

67.2

25.4

37.8

4.3

61.1

ZrO2

120

30

70.9

23.9

33.7

6.1

57.3

SiO2

120

30

75.3

20.8

27.6

6.5

50.3

The initial concentration of glucose was 1.0 wt.%. All the supported MgO samples were calcined at 500 °C for 5 h.

34


Page 35 of 47 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


Table 3 Elements leaching and coke deposition on MgO and MgO/NbP catalysts with and without regeneration.

Catalyst

Run

MgO 40%MgO/NbP500 40%MgO/NbP700

―

Mg leaching (ppm) 426

―

40%MgO/NbP700 with regeneration

―

Nb leaching (ppm) ―

251

61

330

7.2

1 2 3 1

234 130 79 111

61 34 24 44

41 47 17 11

3.2 3.7 4.1 3.0

2

99

36

11

2.9

P leaching (ppm)

Coke (wt.%) 21.5

MgO was reacted with 10.0 wt.% glucose at 90 °C for 30 min; while 40%MgO/NbP catalysts were reacted with10.0 wt.% glucose at 120 °C for 30 min.

Table 4 Effect of initial concentration of glucose on its isomerization over 40%MgO/NbP-700.

Glucose Concentration (wt.%)

Glc Conversion (%)

Fru Yield (%)

Fru Selectivity (%)

Man Selectivity (%)

1.0 5.0 10.0 20.0

46.3 31.0 27.5 16.1

20.8 18.7 18.1 11.1

45.0 60.4 65.5 68.9

6.0 3.5 4.3 6.5

Total Yield of Sugars (%） 77.3 88.8 91.8 96.1

Productivity of fructose (g/kgsolution ·h ) 4.2 18.7 36.3 44.3

Reaction condition: 10.0 wt.% glucose, 120 °C, 30 min, catalyst loading of 0.01 g gsolution‒1. 35



Page 36 of 47

Table 5 Comparison of glucose isomerization over different solid catalysts. 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

Glucose

Catalyst

Reaction

Glucose

Fructose

Fructose

Catalyst

Time

conversion

yield

selectivity

efficiency

(h)

(%)

(%)

(%)

(gfrucose/(gcatalyst·h))

Temp. Catalysts

Protection

Concen.

loading

Ref.

(ºC) (wt.%)

(gcatalyst/gglucose)

Cs exchanged zeolites

N2

9.1

0.2

95

1

10–34

19–22

63–77

0.86–1.00

Hydrotalcite (HT, Mg/Al=2.5)

N2

9.1

0.2

95

1

30

20

66

0.91

HT (Mg/Al=3)

N2

9.1

0.2

95

1

42

25

60

1.14

HT-CO3

‒

1.0

3.33

90

24

41

32

79

0.0041

HT

‒

5.0

2

90

48

31

26

84

0.0027

HT regenerated

‒

10.0

2

90

24

–

10

–

0.0021

Ti-β-zeolite

‒

10.0

~0.67

140

1.5

50

23

45

0.23

Sn-β-zeolite

‒

10.0

~0.67

110

0.5

55

32

58

0.96

Metallosilicates

N2

4.8

0.4

100

2

27–56

21–39

62–84

0.25–0.49

63

10%MgNaY zeolite

N2

10.0

0.2

100

0.5

35

31

87

3.10

51

MgO

–

4.0

0.5

100

1

62

27

44

0.54

43, 44

MgO

–

4.0

0.125

90

0.75

44

33

76

3.52

MgO

–

10.0

0.1

90

0.5

44

21

47

4.20

36


39

23

20

This

Page 37 of 47

1 2 3 4 5 6 7 8 9 10 311 12 413 14 515 16 17 618 19 720 21 822 23 924 25 1026 27 1128 29 1230 31 32 1333 34 1435 36 1537 38 39 40 41 42 43 44 45 46


40%MgO/NbP-700

–

10.0

0.1

120

0.5

28

18

66

3.60

work

40%MgO/NbP-700

–

10.0

0.025

120

0.5

26

17

66

13.60

0

40%MgO/NbP-700 regenerated

–

10.0

0.1

120

0.5

29

19

63

3.80

1 2

37



Page 38 of 47

Supporting Information: The chromatogram of the reference samples and of the reactant of glucose; supplementary characterization of the NbP and Mg/NbP samples; effect of reaction temperature and catalyst loading on the isomerization of glucose.

Corresponding Authors *

D-M. Gao. E-mail: [email protected]

*

H. Liu. E-mail: [email protected]

Acknowledgements Financial support by State Key Laboratory of Food Science and Technology, Jiangnan University (SKLF-ZZB-201811) is gratefully acknowledged.

References (1) Corma, A.; Iborra, S.; Velty, A. Chemical routes for the transformation of biomass into chemicals. Chem. Rev. 2007, 107, 2411−2502. (2) Zhang, X.; Wilson, K.; Lee, A. F. Heterogeneously catalyzed hydrothermal processing of C5– C6 sugars. Chem. Rev. 2016,116, 12328−12368. (3) Makhubela, B. C.; Darkwa, J. The role of noble metal catalysts in conversion of biomass and bio-derived intermediates to fuels and chemicals. Johnson Matthey Technol. Rev. 2018, 62, 4−31.


38

Page 39 of 47 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


(4) Li, H.; Riisager, A.; Saravanamurugan, S.; Pandey, A.; Sangwan, R. S.; Yang, S.; Luque, R. Carbon-increasing catalytic strategies for upgrading biomass into energy-intensive fuels and chemicals. ACS Catal. 2017, 8, 148−187. (5) Lavarack, B. P.; Griffin, G. J.; Rodman, D. The acid hydrolysis of sugarcane bagasse hemicellulose to produce xylose, arabinose, glucose and other products. Biomass Bioenerg. 2002, 23, 367−380. (6) Alonso, D. M.; Wettstein, S. G.; Mellmer, M. A.; Gurbuz, E. I.; Dumesic, J. A. Integrated conversion of hemicellulose and cellulose from lignocellulosic biomass. Energ. Environ. Sci. 2013, 6, 76−80. (7) Xing, R.; Subrahmanyam, A. V.; Olcay, H.; Qi, W.; van Walsum, G. P.; Pendse, H.; Huber, G. W. Production of jet and diesel fuel range alkanes from waste hemicellulose-derived aqueous solutions. Green Chem. 2010, 12, 1933−1946. (8) Zakzeski, J.;

Bruijnincx, P. C.; Jongerius, A. L.; Weckhuysen, B. M. The catalytic

valorization of lignin for the production of renewable chemicals. Chem. Rev. 2010, 110, 3552−3599. (9) Liu Y.; Liu, C. H. Tungsten trioxide promoted selective conversion of cellulose into propylene glycol and ethylene glycol on a ruthenium catalyst. Angew. Chem. Int. Edit. 2012, 124, 3303−3307. (10) Van de Vyver, S.; Thomas, J.; Geboers, J.; Keyzer, S.; Smet, M.; Dehaen, W.; Jacobs, P. A.; Sels, B. F. Catalytic production of levulinic acid from cellulose and other biomass-derived


39


Page 40 of 47

carbohydrates with sulfonated hyperbranched poly (arylene oxindole)s. Energ. Environ. Sci. 2011, 4, 3601−3610. (11) de Beeck, B. O.; Dusselier, M.; Geboers, J.; Holsbeek, J.; Morré, E.; Oswald, S.; Giebeler, L.; Sels, B. F. Direct catalytic conversion of cellulose to liquid straight-chain alkanes. Energ. Environ. Sci. 2015, 8, 230−240. (12) Kobayashi, H.; Komanoya, T.; Guha, S. K.; Hara, K.; Fukuoka, A. Conversion of cellulose into renewable chemicals by supported metal catalysis. Appl. Catal. A−Gen. 2011, 409, 13−20. (13) Alonso, D. M.; Wettstein, S. G.; Dumesic, J. A. Gamma-valerolactone, a sustainable platform molecule derived from lignocellulosic biomass. Green Chem. 2013, 15, 584-595. (14) Yabushita, M.; Kobayashi, H.; Fukuoka, A. Catalytic transformation of cellulose into platform chemicals. Appl. Catal. B−Environ. 2014, 145, 1−9. (15) 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. (16) Lee, H. S.; Hong, J. Kinetics of glucose isomerization to fructose by immobilized glucose isomerase: anomeric reactivity of D-glucose in kinetic model. J. Biotechnol. 2000, 84, 145−153. (17) Izumori, K. Izumoring: a strategy for bioproduction of all hexoses. J. Biotechnol. 2006,124, 717−722.


40

Page 41 of 47 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


(18) Tanase, T.; Takei, T.; Hidai, M.; Yano, S. Substrate-dependent chemoselective aldose– aldose and aldose–ketose isomerizations of carbohydrates promoted by a combination of calcium ion and monoamines. Carbohydr. Res. 2001, 333, 303−312. (19) Topper, Y. J.; Stetten, D. The alkali-catalyzed conversion of glucose into fructose and mannose. J. Biol. Chem. 1951,189, 191−202. (20) Moliner, M.; Román-Leshkov, Y.; Davis, M. E. Tin-containing zeolites are highly active catalysts for the isomerization of glucose in water. PNAS 2010, 107, 6164−6168. (21) Delidovich, I.; Palkovits, R. Catalytic isomerization of biomass-derived aldoses: A review. ChemSusChem. 2016, 9, 547−561. (22) de Bruijn, J. M.; Kieboom, A. P. G.; van Bekkum, H. Alkaline degradation of monosaccharides V: Kinetics of the alkaline isomerization and degradation of monosaccharides. Recl. Trav. Chim. PaysBas. 1987, 106, 35–43. (23) Delidovich, I.; Palkovits, R. Catalytic activity and stability of hydrophobic Mg–Al hydrotalcites in the continuous aqueous-phase isomerization of glucose into fructose. Catal. Sci. Technol. 2014, 4, 4322–4329. (24) Liu, C.; Carraher, J. M.; Swedberg, J. L.; Herndon, C. R.; Fleitman, C. N.; Tessonnier, J. P. Selective base-catalyzed isomerization of glucose to fructose. ACS Catal. 2014, 4, 4295– 4298. (25) Shaw, A. J.; Tsao, G. T. Isomerization of D-glucose with sodium aluminate: mechanism of the reaction. Carbohydr. Res. 1978, 60, 327–325.


41


Page 42 of 47

(26) Despax, S.; Estrine, B.; Hoffmann, N.; Le Bras, J.; Marinkovic, S.; Muzart, J. Isomerization of d-glucose into d-fructose with a heterogeneous catalyst in organic solvents. Catal. Commun. 2013, 39, 35–38. (27) Tang, J.; Guo, X.; Zhu, L.; Hu, C. Mechanistic study of glucose-to-fructose isomerization in water catalyzed by [Al (OH)2 (aq)]+. ACS Catal. 2015, 5, 5097–5103. (28) Choudhary, V.; Sandler, S. I.; Vlachos, D. G. Conversion of xylose to furfural using Lewis and Brønsted acid catalysts in aqueous media. ACS Catal. 2012, 2, 2022–2028. (29) Pagan-Torres, Y. J.; Wang, T.; Gallo, J. M. R.; Shanks, B. H.; Dumesic, J. A. Production of 5-hydroxymethylfurfural from glucose using a combination of Lewis and Brønsted acid catalysts in water in a biphasic reactor with an alkylphenol solvent. ACS Catal. 2012, 2, 930–934. (30) Weingarten, R.; Kim, Y. T.; Tompsett, G. A.; Fernández, A.; Han, K. S.; Hagaman, E. W.; Conner Jr, W. C.; Dumesic, J. A.; Huber, G. W. Conversion of glucose into levulinic acid with solid metal (IV) phosphate catalysts. J. Catal. 2013, 304, 123–134. (31) Kuo, C. H.; Poyraz, A. S.; Jin, L.; Meng, Y.; Pahalagedara, L.; Chen, S. Y.; David, A. K.; Curtis, G.; Anton, G.; Suib, S. L. Heterogeneous acidic TiO2 nanoparticles for efficient conversion of biomass derived carbohydrates. Green Chem. 2014, 16, 785−791. (32) Guo, J.; Zhu, S.; Cen, Y.; Qin, Z.; Wang, J.; Fan, W. Ordered mesoporous Nb–W oxides for the conversion of glucose to fructose, mannose and 5-hydroxymethylfurfural. Appl. Catal. B–Environ. 2017, 200, 611−619.


42

Page 43 of 47 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


(33) Liu, M.; Jia, S.; Li, C.; Zhang, A.; Song, C.; Guo, X. Facile Preparation of Sn-B zeolites by post-synthesis (isomorphous substitution) method for isomerization of glucose to fructose. Chin. J. Catal. 2014, 35, 723−732. (34) Saravanamurugan, S.; Paniagua, M.; Melero, J. A.; Riisager, A. Efficient isomerization of glucose to fructose over zeolites in consecutive reactions in alcohol and aqueous media. J. Am. Chem. Soc. 2013, 135, 5246−5249. (35) Ren, L.; Guo, Q.; Kumar, P.; Orazov, M.; Xu, D.; Alhassan, S. M.; Mkhoyan, K. A.; Davis, M. E.; Tsapatsis, M. Self-pillared, single-unit-cell Sn-MFI zeolite nanosheets and their use for glucose and lactose isomerization. Angew. Chem. Int. Edit. 2015, 54, 10848−10851. (36) de Mello, M. D., Tsapatsis, M. Selective glucose-to-fructose isomerization over modified zirconium UiO-66 in alcohol media. ChemCatChem. 2018, 10, 2417−2423. (37) Langlois, D. P.; Larson, R. F. Interconversion of sugars using anion exchange resins. U.S. Patent 1956, 2746889. (38) Yang, Q.; Zhou, S.; Runge, T. Magnetically separable base catalysts for isomerization of glucose to fructose. J. Catal. 2015, 330, 474–484. (39) Moreau, C.; Durand, R.; Roux, A.; Tichit, D. Isomerization of glucose into fructose in the presence of cation-exchanged zeolites and hydrotalcites. Appl. Catal. A–Gen. 2000, 193, 257–264. (40) Kitajima, H.; Higashino, Y.; Matsuda, S.; Zhong, H.; Watanabe, M.; Aida, T. M.; Smith Jr, R.L. Isomerization of glucose at hydrothermal condition with TiO2, ZrO2, CaO-doped ZrO2 or TiO2-doped ZrO2. Catal. Today 2016, 274, 67−72.


43


Page 44 of 47

(41) Rendleman, J. A.; Hodge, J. E.; Aldose-ketose interconversion on anion-exchange resin (aluminate and hydroxide forms). Carbohydr. Res. 1979, 75, 83−99. (42) López, T.; Gomez, R.; Llanos, M. E.; López-Salinas, E. Acidic–base properties of silica– magnesia sol–gel mixed oxides: use of 2 butanol as test reaction. Mater. Lett. 1999, 38, 283−288. (43) a) Marianou, A. A.; Michail, C. M.; Pineda, A.; Iliopoulou, E. F.; Triantafyllidis, S. K.; Lappas, A. A. Glucose to fructose isomerization in aqueous media over homogeneous and heterogeneous catalysts. ChemCatChem. 2016, 8, 1100−1110; (44) Marianou, A. A.; Michailof, C. M.; Ipsakis, D. K. et al. Isomerization of glucose into fructose over natural and synthetic MgO catalysts. ACS Sustain. Chem. Eng. 2018, 6, 16459−16470. (45) Zhang, X.; Xu, Z.; Li, X.; Guan, J.; Long, J. Chemical isomerization of glucose into fructose. Chem. Ind. Eng. Process 2017, 36, 4575−4585. (46) Knill, C. J.; Kennedy, J. F. Degradation of cellulose under alkaline conditions. Carbohydr. Polym. 2003, 51, 281−300. (47) Yang, B. Y.;

Montgomery, R. Alkaline degradation of glucose: effect of initial

concentration of reactants. Carbohydr. Res. 1996, 280, 27−45. (48) Giordano, L.; Goniakowski, J.; Suzanne, J. Partial dissociation of water molecules in the (3×2) water monolayer deposited on the MgO (100) surface. Phys. Rev. Lett. 1998, 81, 1271−1273.


44

Page 45 of 47 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


(49) Kim, Y. D.; Stultz, J.; Goodman, D. W. Dissociation of water on MgO (100). J. Phys. Chem. B 2002,106, 1515−1517. (50) Johnson, M. A.; Stefanovich, E. V.; Truong, T. N.; Günster, J.; Goodman, D. W. Dissociation of water at the MgO (100)‒water interface: Comparison of theory with experiment. J. Phys. Chem. B 1999,103, 3391−3398. (51) Graça, I.; Iruretagoyena, D.; Chadwick, D. Glucose isomerisation into fructose over magnesium-impregnated NaY zeolite catalysts. Appl. Catal. B−Environ. 2017, 206, 434−443. (52) Graça, I.; Bacariza, M. C.; Chadwick, D. Glucose isomerisation into fructose over Mgimpregnated Na-zeolites: Influence of zeolite structure. Micropor. Mesopor. Mat. 2018, 255, 130−139. (53) Gao, D.-M.; Zhao, B.; Liu, H.; Morisato, K.; Kanamori, K.; He, Z.; Zeng, M.; Wu, H.; Chen, J., Nakanishi, K. Synthesis of a hierarchically porous niobium phosphate monolith by a sol– gel method for fructose dehydration to 5-hydroxymethylfurfral. Catal. Sci. Technol. 2018, 8, 3675−3685. (54) Di Cosimo, J. I.; Díez, V. K.; Ferretti, C. A.; Apesteguía, C. R. Basic catalysis on MgO: generation, characterization and catalytic properties of active sites. Catal. 2014, 26, 1−28. (55) Di Cosimo, J. I.; Díez, V. K.; Xu, M.; Iglesia, E.; Apesteguía, C. R. Structure and surface and catalytic properties of Mg-Al basic oxides. J. Catal. 1998, 178, 499−510.


45


Page 46 of 47

(56) Díez, V. K.; Ferretti, C. A.; Torresi, P. A.; Apesteguía, C. R.; Di Cosimo, J. I. Effect of MgO activation conditions on its catalytic properties for base-catalyzed reactions. Catal. Today 2011,173, 21−27. (57) Belin, T., Mfoumou, C. M.; Mignard, S.; Pouilloux, Y. Study of physisorbed carbon dioxide on zeolites modified by addition of oxides or acetate impregnation. Micropor. Mesopor. Mat. 2013, 182, 109−116. (58) Bhagiyalakshmi, M.; Lee, J. Y.; Jang, H. T. Synthesis of mesoporous magnesium oxide: its application to CO2 chemisorption. Int. J. Greenh. Gas Con. 2010, 4 51−56. (59) Ordomsky, V. V.; Sushkevich, V. L.; Schouten, J. C.; Van der Schaaf, J.; Nijhuis, T. A. Glucose dehydration to 5-hydroxymethylfurfural over phosphate catalysts. J. Catal. 2013, 300, 37−46. (60) García‒Sancho, C.; Sádaba, I.; Moreno‒Tost, R.; Mérida‒Robles, J.; Santamaría‒González, J.; López‒Granados, M.; Maireles‒Torres, P.

Dehydration of xylose to furfural over

MCM‒41‒supported niobium‒oxide catalysts. ChemSusChem 2013, 6, 635‒642. (61) Nakajima, K.; Baba, Y.; Noma, R.; Kitano, M.; Kondo, J. N.; Hayashi, S.; Hara, M. Nb2O5·nH2O as a heterogeneous catalyst with water-tolerant Lewis acid sites. J. Am. Chem. Soc. 2011,133, 4224−4227. (62) 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.


46

Page 47 of 47

(63) Lima, S.; Dias, A. S.; Lin, Z.; Brandão, P.; Ferreira, P.; Pillinger, M.; Rocha, J.; CalvinoCasilda, V.; Valente, A. A. Isomerization of D-glucose to D-fructose over metallosolicate solid bases. Appl. Catal. A‒Gen. 2008, 339, 21‒27.

Graphic Abstract

100

Yield of glucose and fructose Selectivity of fructose (%)

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


H

80

60 MgO/NbP

Yield of Glc

40 Selectivity of Fru 20

Yield of Fru 0 0

50

100

150

200

Reaction time (min) Synopsis Glucose was effectively isomerized over niobium phosphate supported MgO in green condition.


47

Macroporous Niobium Phosphate-Supported Magnesia Catalysts for

Recommend Documents