Fructose Yield Research Articles

Study of glucose isomerisation to fructose over three heterogeneous carbon-based aluminium-impregnated catalysts

Driven by the worldwide demand for sustainable resources and renewable energy, the synthesis of bio-based platform chemicals has attracted broad interest. The isomerisation of glucose to fructose acts as a critical intermediate step among many chemical synthesis routes. In this study, biochar (BC), graphitic oxide (GIO), and graphene oxide (GO) were used as carbon supports to synthesize Al-impregnated heterogeneous catalysts, which were then used for glucose isomerisation under microwave heating in the water at 140 °C. The kinetics model with parameters was used to reveal the interplay of the active sites and compare the activity of the three carbon-based catalysis systems. Catalyst characterisation results showed effective aluminium (Al) impregnation onto the three types of catalysts, and it was found that GIO-Al200 and GO-Al200 showed comparable catalytic activity (fructose yield of 34.3–35.0%) for glucose isomerisation. At the same time, BC-Al200 exhibited slightly lower catalytic activity (fructose yield of 29.4%). The conversion kinetics suggested similar catalytic mechanisms on the three catalysts while BC-Al200 manifested slower kinetics, possibly implying higher activation energy. The fructose selectivity decreased with increasing time due to the formation of side products, yet BC-Al200 resulted in less carbon loss than GIO-Al200 and GO-Al200, probably attributed to its lower catalytic activity and higher pH buffering capacity. A green synthesis route of this study promotes biomass valorisation and makes engineered biochar a promising carbon-based catalyst for sustainable biorefinery.

Ball-milled, solvent-free Sn-functionalisation of wood waste biochar for sugar conversion in food waste valorisation

The use of biomass wastes for biochar production is a promising waste management option, and biochars can be potentially applied in the food waste recycling industry to produce value-added chemicals. In this study, an advanced Sn-functionalised biochar catalyst was synthesised via a novel solvent-free ball milling protocol to facilitate the isomerisation of glucose to fructose. Raw wood biomass (W) and its derived biochars pyrolysed at low (LB, 400 °C) and high (HB, 750 °C) temperatures were investigated as catalyst supports. The interactions between Sn and the carbonaceous supports were related to the surface chemistry of the catalysts. The raw W had a functional group-enriched surface, which provided more active sites for anchoring Sn, resulting in higher metal loading on the support compared to LB and HB. The annealing temperature was another critical factor determining the amount and speciation of loaded Sn. Catalytic conversion experiments indicated that SnW annealed at 750 °C exhibited the best fructose yield (12.8 mol%) and selectivity (20.2 mol%) at 160 °C for 20 min. The catalytic activity was mainly determined by the quantity and nature of active Sn sites. This study elucidated the roles of the carbon support and its surface chemistry for synthesising biochar-supported catalysts, highlighting a simple and green approach for designing effective solid catalysts for sustainable biorefineries.

Green synthesis of aluminum-hydrochar for the selective isomerization of glucose to fructose

Hydrochar microspheres supported Al catalysts with hierarchically porous structure (Al/HPHMs) for glucose to fructose isomerization were fabricated. Superior catalytic selectivity (93.3%) and fructose yield (32.6%) were achieved in aqueous under 160 °C for 20 min. Hierarchically porous structure was formed after KHCO3 and K2CO3 activation and the roles of KHCO3 and K2CO3 in controlling the Al phase and tailoring morphology of hydrochar supported Al were evaluated. The major active sites were characterized as Al hydroxides including β-Al(OH)3, γ-Al(OH)3, γ-AlO(OH), Al-C-O linkages. Active sites by KHCO3 activation with high contents of Al-C-O and Al(OH)3 have better selectivity. Oxygen-containing functional groups including aluminum‑oxygen groups on the hydrochar microspheres have contributed to the formation of hydrogen bond and π-π interactions between glucose and Al species. Green process synthesized aluminum-hydrochars have potential for their application as a variety of stable, recyclable, and efficient catalysts for lignocellulosic biorefining.

Silica supported Sn catalysts with tetrahedral Sn sites for selective isomerization of glucose to fructose

Lewis acid catalyzed isomerization of glucose to fructose is an important reaction for production of renewable chemicals. Here, we show the synthesis of an active and selective Lewis acid catalyst for this reaction by controlling Sn dispersion on SBA15. Sn loading of 1 wt. % over SBA15 (Sn/SBA15) maximized the formation of tetrahedral Sn species on the catalyst surface. Increasing the loading or changing support caused formation of SnO2 clusters which reduced fructose selectivity. A mechanism based on condensation of Sn with silanol group of SBA15 is proposed. The catalyst showed high selectivity of 93 % after 2 h with 57 % fructose yield. The Lewis acid catalyzed isomerization of glucose was proven by isotopic tracer study using d-glucose-2-d. The catalyst deactivated in the third cycle owing to byproduct deposition, but the activity was restored by recalcining the catalyst.

Modified Versions of AM‐4 for the Aqueous Phase Isomerization of Aldo‐Saccharides

The isomerization of aldo‐saccharides to keto‐saccharides is an important transformation in biomass conversion processes. The use of eco‐friendly heterogeneous catalysts for these reactions is most attractive, albeit good catalytic stability continues a challenge. The as‐synthesized Aveiro‐Manchester material number 4 (AM‐4, Na3(Na,H)Ti2O2[Si2O6]2,2H2O) possessed isomerization activity, but limited stability. This versatile precursor material was modified to meet superior performances in the base‐catalyzed isomerization of the monosaccharides d‐glucose and d‐xylose, and the disaccharide d‐cellobiose, at 100 °C. Different alkali and alkaline‐earth metals were introduced into AM‐4, which influenced the catalytic properties. The Mg‐containing material was the most stable, leading to 27 % fructose yield from d‐glucose, 41 % cellobiulose from d‐cellobiose and 39 % xylulose from d‐xylose isomerization, at 2 h reaction.

Heterotrophic cultivation of Ettlia sp. based on sequential hydrolysis of Helianthus tuberosus and algal residue

Heterotrophic cultivation of microalgae results in substantial productivity but requires significant nutrient input. Alternative sources of major nutrients such as C and N should be carefully selected to make heterotrophic production of microalgal biomass feasible. In this study, Helianthus tuberosus and lipid-extracted algae (LEA) were hydrolyzed with sulfuric acid to grow Ettlia sp. YC001. Hydrolysis of H. tuberosus with 0.3 N of sulfuric acid resulted in fructose yield of 0.51 g g−1 and glucose yield of 0.14 g g−1 at 80 °C in 1 h. Proteolysis of algal residue with 2 N of sulfuric acid resulted in amino acid yield of 0.38 g g−1 at 110 °C in 24 h. To simplify the production of hydrolysates, the hydrolysis conditions were combined to establish a tailored sequential hydrolysis process. Then, simultaneous neutralization and salt removal of the hydrolysates were done with barium hydroxide. Consequently, cultivation of Ettlia sp. with the diluted sequential hydrolysate of H. tuberosus and LEA successfully achieved 5.90 g L−1 d−1 of biomass productivity and 1.42 g L−1 d−1 of lipid productivity with Ettlia sp.

Facile Molecular Catalysis for Isomerization of Glucose to Fructose Using KMnO4 in Water

AbstractThis research demonstrates the eco‐friendly conversion of glucose to fructose in an aqueous solution of potassium permanganate (KMnO4) via a hydrothermal method. A series of reactions have been completed at different temperatures, times, and concentrations of the catalyst. The examination of the glucose to fructose transformation was determined by using quantitative HPLC, and 13C‐NMR analyses. 29% fructose yield was found with 68% fructose selectivity, at 90 °C for an 8 h reaction in aqueous solution. The catalytic activity of KMnO4 was correlated with its Lewis acidity. The outcomes of these experiments provided a better understanding of sugar transformations in the KMnO4 aqueous solution. The mechanism of glucose isomerization has been proposed based on supporting transformations utilizing Lewis acids for the isomerization of glucose.

Dehydration of Fructose to 5-HMF over Acidic TiO2 Catalysts.

Different solid sulfonic titania-based catalysts were investigated for the hydrothermal dehydration of fructose to 5-hydroxymethylfurfural (5-HMF). The catalytic behavior of the materials was evaluated in terms of fructose conversion and selectivity to 5-HMF. The surface and structural properties of the catalysts were investigated by means of X-ray diffraction (XRD), N2 adsorption isotherms, thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and acid capacity measurements. Special attention was focused on the reaction conditions, both in terms of 5-HMF selectivity and the sustainability of the process, choosing water as the solvent. Among the various process condition studied, TiO2-SO3H catalyzed a complete conversion (99%) of 1.1M fructose and 5-HMF selectivity (50%) and yield (50%) at 165 °C. An important improvement of the HMF selectivity (71%) was achieved when the reaction was carried out by using a lower fructose concentration (0.1M) and lower temperature (140 °C). The catalytic activities of the materials were related to their acid capacities as much as their textural properties. In particular, a counterbalance between the acidity and the structure of the pores in which the catalytic sites are located, results in the key issue for switch the selectivity towards the achievement of 5-HMF.

Efficient Conversion of Glucose into Fructose via Extraction-Assisted Isomerization Catalyzed by Endogenous Polyamine Spermine in the Aqueous Phase.

In the present study, natural polyamine spermine is demonstrated as a potential basic catalyst for glucose-to-fructose isomerization. For instance, spermine achieves a decent fructose yield (30% wt) and selectivity (74%) during the single-step aqueous phase isomerization under the modest operating conditions (100 °C for 15 min). In addition to the expected reaction byproduct monosugar mannose, spermine also assists in the synthesis of rare and important monosugar, that is, psicose up to 4% wt. Psicose is a zero calorie rare sugar, exhibits a low caloric value, and possesses anti-adipogenic property. A comparative study involving other polyamines concluded that the presence of 20 amines tends to exhibit the most significant impact in improving the target product yield by releasing a higher number of OH– ions, which are responsible for isomerization through the formation of an enediol anion. An attempt was made to further improve the fructose yield through the addition of neutral salts, but it promoted a meager achievement. In an alternate study, a selective extraction strategy was followed for the isolation of fructose from the reaction mixture. The employed aryl monoboronic acid remarkably improved the net fructose concentration, that is, fructose productivity up to 75% wt (cumulative) and 70% selectivity within three consecutive extractions and isomerization cycles, which is comparatively three times shorter than that reported in the literature. Notably, spermine itself provided the essential and necessary basic environment for selective fructose extraction and glucose isomerization, ruling out the use of any external reagents and thus establishing itself as a versatile material suitable for a typical isomerization reaction in an upscaled reactor.

Isomerization Kinetics of Glucose to Fructose in Aqueous Solution with Magnesium‐Aluminum Hydrotalcites

AbstractMg−Al hydrotalcites for catalyzing glucose isomerization to fructose are prepared. Effects of atom ratios of Mg/Al ranging from 1 to 4 and calcination temperatures from 250–650 °C on catalytic performance were examined systematically. It was found that the hydrotalcite (Mg2Al1LDH) calcined at 450 °C with an atom ratio of Mg/Al=2 is an excellent catalyst for glucose isomerization. Characterizations by SEM, EDS, TEM, XRD, FTIR, TG and BET demonstrated that the formed oxide condensed phase as well as the interaction with the alumina helps promote glucose isomerization reaction due to their appropriate basic sites at high calcination temperature. With Mg2Al1‐450 as the catalyst, kinetic model analysis confirmed that the reaction of glucose isomerization to fructose was an exothermal reversible reaction; both the forward and reverse reactions are quasi‐first‐order reactions with activation energies of 71.82 kJ/mol and 48.15 kJ/mol, respectively, while the side reaction is a zero‐order reaction with an activation energy of 94.22 kJ/mol. Therefore, high isomerization reaction temperature is not beneficial to enhance the yield and selectivity of fructose.

MgO-ZrO2 Mixed Oxides as Effective and Reusable Base Catalysts for Glucose Isomerization into Fructose in Aqueous Media.

MgO-ZrO2 mixed oxides prepared with different Mg/Zr atomic ratios (denoted as xMZ: where x is the atomic ratio of Mg/Zr) are investigated for the glucose isomerization to fructose in water at 95 °C. The highest fructose yield of 33 % is obtained over 0.76MZ with ≈74 % selectivity after 3 h. To gain insight into the structure-activity relationships, the prepared catalysts are characterized by N2 physisorption, XRD, FTIR and CO2 -TPD. The results indicate that the addition of MgO drastically changed the textual property of ZrO2 and increased the number of basic sites. The kinetic studies revealed that the Lewis basic sites (cus-O2- ) generated from the highly dispersed MgO are the active sites responsible for the enhanced isomerization activity. Notably, MZ is reusable for four runs without a significant decrease in catalyst activity. Accordingly, this study provides an easily prepared, cheap, and recyclable catalyst that may hold great potential for fructose production.

Glucose Isomerizes to Fructose Catalyzed by the Eco‐Friendly and Biodegradable Ionic Liquids

AbstractIn this study, a new and cost‐effective strategy is proposed for the selective isomerization of glucose to fructose in the aqueous solutions involving eco‐friendly and biodegradable ionic liquids, which consist of a choline cation and natural amino acid anions. The results show that these ionic liquid aqueous solutions demonstrate impressive performances on the glucose isomerization. At the reaction conditions of 70 °C for 30 min and 1.0 MPa N2, a 37.6% fructose yield is obtained with a 77.2% selectivity in the presence of choline proline. It is noteworthy that both of these fructose yield and selectivity are higher than those of many current base‐catalyzed techniques. This high performance should be ascribed to the intensive enhancement of choline cation on the catalytic active centre of proline anion which consequentially facilitates the isomerization of glucose. Furthermore, this robust catalyst of [Ch]Pro is recyclable, where a satisfied catalytic activity is shown even after five consecutive runs, indicating its great potential in both biomass valorization and food industry.

Tailoring acidity and porosity of alumina catalysts via transition metal doping for glucose conversion in biorefinery

Efficient conversion of food waste to value-added products necessitates the development of high-performance heterogeneous catalysts. This study evaluated the use of Al2O3 as a low-cost and abundant support material for fabricating Lewis acid catalysts, i.e., through the in-situ doping of Cu, Ni, Co, and Zr into Al2O3 followed by calcination. The characterisation results show that all catalysts were mainly amorphous. In particular, adding the transition metals to the Al2O3 matrix resulted in the increase of acidity and meso-/micro-pores. The catalysts were evaluated in the conversion of glucose, which can be easily derived from starch-rich food waste (e.g., bread waste) via hydrolysis, to fructose in biorefinery. The results indicate that the Ni-doped Al2O3 (Al-Ni-C) achieved the highest fructose yield (19 mol%) and selectivity (59 mol%) under heating at 170 °C for 20 min, of which the performance falls into the range reported in literature. In contrast, the Zr-doped Al2O3 (Al-Zr-C) presented the lowest fructose selectivity despite the highest glucose conversion, meaning that the catalyst was relatively active towards the side reactions of glucose and intermediates. The porosity and acidity, modified via metal impregnation, were deduced as the determinants of the catalytic performance. It is noteworthy that the importance of these parameters may vary in a relative sense and the limiting factor could shift from one parameter to another. Therefore, evaluating physicochemical properties as a whole, instead of the unilateral improvement of a single parameter, is encouraged to leverage each functionality for cost-effectiveness. This study provides insights into the structure-performance relationships to promote advance in catalyst design serving a sustainable food waste biorefinery.

Highly Efficient Hydrotalcite/1-Butanol Catalytic System for the Production of the High-Yield Fructose Crystal from Glucose

Catalytic isomerization of glucose to fructose is a key step for the synthesis of bioplastics and biofuels as well as sweeteners. In this study, a record fructose yield of greater than 50% with sel...

N-Doped Carbon Materials as Heterogeneous Catalysts for High Efficiency Isomerization Glucose to Fructose in Aqueous Media

Fructose is not only an important food and beverage ingredient, but also a renewable resource for production of bio-chemicals. In this paper, a series of N doped mesoporous carbon materials (MCNs) were prepared and evaluated as heterogeneous catalysts for catalytic isomerization of glucose to fructose. The MCNs were prepared through carbonization of p-phenylenediamine disulfate and the effects of desulfonation with NaOH and hydrogenation treatments were examined. It is found that the molar ratio of H2SO4/pPDA crucially affects the porous structure and the nitrogen content. Desulfonation with NaOH treatment could largely eliminate the sulfonic groups on the carbon edges and thus enhance the basicity of the MCN materials, whereas hydrogenation reduction could modify the N atom species and reinforce the strength of the basic sites, as a result enhancing the catalytic activities in glucose isomerization to fructose. Among all of the prepared MCN samples, MCN-2-DH showed an excellent activity in aqueous solution, which afforded a fructose yield of 31.6% with 84.6% selectivity.

ZIF-8 Metal Organic Framework for the Conversion of Glucose to Fructose and 5-Hydroxymethyl Furfural

Herein, Zeolitic imidazolate framework-8 (ZIF-8) is considered as an easy and cheap to prepare alternative catalyst for the isomerization of glucose and production of 5-hydroxymethyl furfural (HMF). For the synthesis of the ZIF-8 catalysts two preparation methods were evaluated, being room temperature and hydrothermal synthesis at 140 °C. Of these, the hydrothermal synthesis method yields a material with exceptionally high surface area (1967 m2·g−1). As a catalyst, the ZIF-8 materials generated excellent fructose yields. Specifically, ZIF-8 prepared by hydrothermal synthesis yielded a fructose selectivity of 65% with a glucose conversion of 24% at 100 °C in aqueous reaction medium. However, this selectivity dropped dramatically when the reactions were repeated at higher temperatures (~140 °C). Interestingly, greater quantities of mannose were produced at higher temperatures too. The lack of strong Brønsted acidity in both ZIF-8 materials resulted in poor HMF yields. In order to improve HMF yields, reactions were performed at a lower pH of 1.0. At 140 °C the lower pH was found to drive the reaction towards HMF and double its yield. Despite the excellent performance of ZIF-8 catalysts in batch reactions, their activity did not translate well to the flow reactor over a continuous run of 8 h, which was operating with a residence time of 6 min. The activity of ZIF-8 halved in the flow reactor at 100 °C in ~3 h, which implies that the catalyst’s stability was not maintained in the long run.

Tuneable functionalities in layered double hydroxide catalysts for thermochemical conversion of biomass-derived glucose to fructose

Layered double hydroxides (LDHs) with varying crystallite sizes (2.6–43 nm), layer numbers (3–70), specific surface area (18–455 m2 g−1), pore volume (0.025–1.6 mL g−1), and functional groups were synthesised via conventional urea hydrolysis and co-precipitation methods and aqueous miscible organic solvent (AMOST) treatment. They were evaluated as the solid base catalysts for the thermochemical isomerisation of biomass-derived glucose to fructose with the aim of establishing the structure-performance relationships for carbon-efficient biorefinery. The results showed that the fructose yield increased with increasing crystallite size of LDHs due to the enhanced exposure of active sites. However, excessive increase in the structural accessibility could be detrimental because high hydrophilicity potentially resulted in water clusters surrounding the active sites and hindering their interaction with glucose. Nano-sized particles in small quantity that were visually indiscernible may partially account for the catalytic activity. The kinetics test suggested that the conversion of glucose to intermediates may act as the rate-determining step when the reaction temperature increased. The activation energy for the LDH-catalysed glucose conversion was estimated to be 52.8 kJ mol−1. The highest fructose yield of 25 mol% was achieved at 120 °C for 5 min in water. The recycling test suggested that the catalytic performance became stable after the second run, possibly due to the formation of a passive layer. This study elucidates the structure-controlled functionalities of the LDH catalysts to serve a base-catalysed biorefinery reaction, and provides mechanistic insights into the active components and the catalyst transformation during thermochemical biomass conversion.

Tin Grafted on Modified Alumina-Catalyzed Isomerisation of Glucose to Fructose

The present study focuses on designing a catalyst based on hot water treated alumina (Al2O3-HWT) for the conversion of glucose to fructose. The glucose isomerisation reactions are performed with tin incorporated on parent Al2O3 and Al2O3-HWT in methanol. 0.5 wt% Sn/Al2O3-HWT affords a combined yield of fructose and methylfructoside (30.4%) which is two-fold higher than that obtained with 0.5wt% Sn/Al2O3 (15.1%), implying the importance of hot water treatment of Al2O3. Al2O3-HWT shows a very broad peak centred around 3440 cm-1, which could be assigned to OH stretching band of gibbsite, γ-Al(OH)3 which significantly diminished after solid state ion-exchange with SnCl4.5H2O (0.5 wt% Sn/Al2O3-HWT). UV-Vis diffused reflectance spectrum of 0.5 wt% Sn/Al2O3-HWT displays a peak centered at 241 nm, which can be ascribed to the incorporation of tin into the alumina network. XRD patterns of 0.5, 3 and 5 wt% Sn/Al2O3-HWT show that no peak corresponding to SnO2 is formed. Importantly, 0.5wt% SnO2/Al2O3-HWT exhibits a low activity, giving 13.2% of the total yield of fructose and methylfructoside, respectively, compared to 0.5wt% Sn/Al2O3-HWT (30.4% fructose), signifying the role of incorporated tin into the alumina network.

Highly Selective Isomerization of Glucose into Fructose Catalyzed by a Mimic Glucose Isomerase

AbstractAn amphoteric phenolic compound with carboxyl and amino functional groups was synthesized and used as mimic glucose isomerase to catalyze the isomerization of glucose into fructose. The mimic enzyme displayed excellent catalytic activity for isomerization of glucose to fructose under mild conditions. The yield of fructose and selectivity of fructose could reach 33.0 % and 93.5 % after reacting 4 h, respectively, at pH 8.5 and 80 °C. The catalysis reaction rate constant kcat and Michaelis constants KmG, KmF were calculated. The activation energy of glucose to fructose was evaluated as 65.9 kJ mol−1. The possible catalysis reaction mechanism was proposed. The acid‐base groups on the catalyst play an important role in proton extraction and transfer, as well as in the rotation of local carbon chain, which leads to the highly selective isomerization of glucose into fructose under mild conditions.

Tin-Functionalized Wood Biochar as a Sustainable Solid Catalyst for Glucose Isomerization in Biorefinery

This study tailored a novel engineered biochar as a solid catalyst for glucose isomerization by pyrolyzing Sn-functionalized wood waste under varying hypothesis-driven selected conditions (i.e., 650, 750, and 850 °C in N2 and CO2 atmosphere). The results showed that properties of biochar support (e.g., porosity and acid/base property) and chemical speciation of Sn were highly related to their catalytic performance. Variations in pyrolysis temperature and feed gas modified the porous structure and surface functionality of biochar as well as the valence state of doped Sn on the biochar. For the N2 biochars, higher pyrolysis temperature enhanced the fructose yield yet had trivial effect on the selectivity, where 12.1 mol % fructose can be obtained at 150 °C and 20 min using biochar produced at 850 °C. This was plausibly attributed to the increased fraction of amorphous Sn structures and metallic Sn that were more reactive than its oxide form. At the pyrolysis temperature of 750 °C, the use of CO2 increased t...