Isomerization Of Glucose Research Articles

Investigating the impact of micropore volume of aminosilica functionalized SBA-15 on catalytic activity for amine-catalyzed reactions

Mesoporous materials such as SBA-15 are used in many applications since the materials are robust and have tunable properties. Whereas these materials are thought to be ideal, the materials are complex with the common synthesis methods producing materials that contain micropores. This work will investigate the impact of micropores on catalytic activity of aminosilica materials. For comparison, materials are formed using a standard method that produces materials with micropores (REG-SBA-15) and using a modified method that produces materials with negligible micropore volume (NMP-SBA-15). After grafting the calcined support with an aminosilane (either (N-methyl amino propyl) trimethoxy silane (denoted as 2°Am) or (N,N-diethyl-3-amino propyl) trimethoxy silane (3°Am)), catalytic testing experiments reveal that NMP-SBA-15 functionalized materials are more active than REG-SBA-15 functionalized materials for a range of reactions. The reactions include (a) glucose isomerization where amines interacting with surface silanols limit catalytic activity and (b) aldol and Knoevenagel chemistry where amine-silanol interactions increase the reaction rate. For aldol chemistry, the observed difference in rate is further investigated using site quantification experiments. Interestingly, the results reveal that three types of sites exist for each material, including sites that are (1) highly active, (2) intermediate active, and (3) inactive. NMR experiments indicate that amines immobilized on REG-SBA-15 supports are less mobile than amines on NMP-SBA-15. For REG-SBA-15, the materials are found to have aminosilanes that have limited mobility and the largest fraction of inactive sites, which suggests that the inactive catalytic sites are in the micropores. Overall, the design of highly active catalytic materials can be achieved using materials that have limited micropore volumes.

Site isolated Ru clusters and sulfoacids in a yolk-shell nanoreactor towards cellulose valorization to 1,2-propylene glycol

Direct conversion of cellulose to high yield 1,2-propylene glycol (1,2-PG) is amazing in the biomass valorization to diols, since this process is atom-economic, carbon neutral, and the produced 1,2-PG has a large market demand. However, it is very challenging to control cellulose hydrogenolysis owing to high reactivity of intermediates (like glucose) and metal-acid repelling, leading to decreased selectivity of metal-acid multi-functional catalysts. Aimed at this, we herein developed a highly selective metal-acid catalyst (Ru/NC@void@MC-SO3H) with site isolated Ru clusters (1.4 nm) on the core and sulfoacids on the shell in a yolk-shell nanoreactor by a layer-by-layer assembly before chemical transformation. The spatial isolation of metal and acid sites integrated in a mesoporous yolk-shell nanoreactor not only facilitates the metal-acid synergism in hydrolysis, isomerization/hydrogenolysis and hydrogenation cascade reactions, but also provides a designated diffusion pathway that is favorable for reaction species. As expected, the elaborately fabricated Ru/NC@void@MC-SO3H proves to be highly selective to 1,2- PG (38 % yield), delivering a productivity of 342.86 mol h−1 gRu–1 and an extremely high turnover number of 173264, outperforming the state-of-art metal-acid catalysts for cellulose hydrogenolysis to 1,2-PG. Our characterization and performance test suggest that sulfoacids are mainly responsible for cellulose hydrolysis, while N-stabilized Ru centers contribute to the glucose isomerization to fructose and its further hydrogenolysis to dihydroxyacetone, followed by hydrogenation to 1,2-PG on metallic Ru species. The acidity and basicity optimized for site isolated Ru/NC@void@MC-SO3H is beneficial to balance intermediate reactions, rendering a higher selectivity to target 1,2-PG. The concept illustrated in this study will provide a guide for the development of other site isolated multi- functional catalysts towards cellulosic biomass conversion and other cascade reactions.

A 2D metal–organic framework with dual‐acidic sites for the valorization of saccharides to 5‐hydroxymethylfurfural

AbstractThe conversion of macromolecular saccharides (fructose, glucose, sucrose, and inulin) to 5‐hydroxymethylfurfural (HMF) is often limited by the mass transfer resistance of existing catalysts. Herein, a two‐dimensional metal–organic framework (NUS‐8‐PhSO3H) containing high densities of dual acidic sites (Lewis and Brønsted acid sites) was developed for the first time by diazo grafting. Characterization results and reaction kinetics showed that the rapid molecular diffusion leads to an unusual pseudozeroth reaction order and a considerably lower apparent activation energy for the fructose reaction over NUS‐8‐PhSO3H in contrast to the first order and higher activation energy over three‐dimensional counterpart (NUS‐16‐PhSO3H) and reported catalysts. In addition, NUS‐8‐PhSO3H can also produce substantially high HMF yields and has a low activation energy for other saccharides (glucose, sucrose, and inulin) by powerful tandem steps, including polysaccharide hydrolysis, glucose isomerization, and fructose dehydration. The preparation of hydrophobic acidic NUS‐8‐PhSO3H provides an efficient means of synthesizing HMF from various saccharides.

Chromium Oxide-modified Mesoporous Zirconium Dioxide: Efficient Heterogeneous Catalyst for the Synthesis of 5-Hydroxymethylfurfural.

A highly efficient carbohydrate conversion to 5-hydroxymethylfurfural (5-HMF) is a promising method to achieve green and sustainable development. However, most currently reported strategies are energy consuming, and the 5-HMF yield is relatively lower in the aqueous phase. Herein, a facile method is reported to obtain effective Cr/ZrO2 catalysts with high acidity and their catalytic performances were investigated for catalyzing fructose to 5-HMF at different temperatures and times. With the catalysis of 15 % Cr/ZrO2 catalyst, the highest fructose conversion of 98 %, 5-HMF yield of 48.8 %, and 5-HMF selectivity of 49.8 % are achieved in green solvent with good recyclability. The possible reaction process of the improved catalysis performance is attributed to the highly crystalline and strong acidity of the Cr/ZrO2 catalyst. The Lewis acid sites could increase the overall rate of fructose conversion by promoting side reactions and might suppress fructose to glucose isomerization. In addition, Cr leakage during the reaction might act as the Bronsted acids to catalyze the fructose dehydration to 5-HMF. The reported method of introducing chromium oxides into ZrO2 catalyst will open a new avenue to promote the practical application of biomass and sustainable development in the future.

Thermochemical property predictions in biomass transformation to fuel components and value-added chemicals

Biomass transformation to fuel and platform chemicals is of an immense interest in the world. The thermochemical data for various reactions involved during biomass transformations to fuel components, fuels and platform chemicals has been investigated using highly accurate Gaussian-4 (G-4) method. Glucose to 5-hydroxymethyl furfural (5-HMF) conversion is a two-step pathway, where first step, glucose isomerization to fructose is highly endothermic with high activation energies. 5-HMF upgradation can be carried through hydrogenation, oxidation, condensation and rehydration. Upgradation of HMF to fuel and value-added chemicals (VAC) is industrially important process that can reduce the demand of petrochemical based products. Thermochemical calculations predict the hydrogenation of 5-HMF to 2,5 dimethyl furan (2,5 DMF) is feasible and follow either pathways with dihydroxy methyl furan (DHMF) and methyl furan (MF) as intermediates. The total Gibb’s Free energy difference for the 5-HMF transformation to 2,5 DMF is highly exothermic. The condensation, rehydration and oxidation reactions of 5- HMF also predicted to be feasible and highly exothermic in nature, that can have potential application in industrial processes. Ethanol is mixed with petrol to run the vehicle on reduced fuel. Ethanol can be obtained from glucose following glycolysis pathway, breaking C-6 sugar to two C-3 sugars. Glyceraldehyde and pyruvic acid are the intermediates in the glycolysis cycle with positive Gibbs free energy change, hence require high temperature.

DFT and dynamic analysis of glucose alcoholysis conversion to 5-ethoxymethylfurfural and ethyl levulinate

An effective catalytic strategy for the conversion of glucose to 5-ethoxymethylfurfural (EMF) catalyzed by ultrastable Y zeolite (USY) in a co-solvent system was developed. Effects of co-solvent and reaction conditions were first investigated. Tetrahydrofuran (THF) with low dipolarity/polarizability (π*) was screened as the appropriate co-solvent, and a higher EMF yield of 41.46% was obtained as the ratio of ethanol to THF was 7:3. The macroscopic reaction kinetic study indicated that THF can protect EMF from easy degradation to EL. Moreover, the reusability and the characterization of USY verified the feasibility of USY as an efficient solid acid catalyst. In this study, density functional theory (DFT) calculations for the catalytic mechanism and solvent effect at the molecular scale were performed for the first time. The extra-framework aluminum species (EFAL), in which Al3+ played an essential role in the reaction as the preferred EFAL species, and THF can reduce the energy barrier of USY-catalyzed glucose isomerization. Meanwhile, the inhibitory effect of THF on EMF alcoholysis was explored via the frontier molecular orbital theory. The results showed that THF increased the LUMO energy of EMF compared with ethanol and γ-valerolactone, which decreased its susceptibility to nucleophilic attack and reduced the adverse alcoholysis of EMF and humins formation. This study provided an enlightening reference for the efficient synthesis of EMF from carbohydrates catalyzed by solid acid catalyst under solvent effect.

Exploring Acrylamide and 5-Hydroxymethylfurfural Formation in Glucose-Asparagine-Linoleic Acid System With a Kinetic Model Approach.

In the “glucose-asparagine-linoleic acid” ternary system, a kinetic model approach was used to explore formation and elimination law of target hazards, including acrylamide (AA) and 5-hydroxymethylfurfural (5-HMF), and their related precursors and intermediate products. The results showed that the elimination of glucose and asparagine and the formation of fructose (generated from glucose isomerization), 3-deoxyglucosone (3-DG), methylglyoxal (MGO), and glyoxal (GO), AA and 5-HMF followed first-order reaction kinetics with high fit coefficients (R2 > 0.9). In addition, the kinetic reaction rate constants increased as the increasing temperature, and all models followed the Arrhenius law. Results of statistical correlations analysis suggested that at lower temperature, the generic amino acid route and the specific amino acid route may paly crucial roles for the formation of AA and 5-HMF, while at high temperature a linoleic acid pathway may be predominantly involved.

Aluminum‐Containing Metal‐Organic Frameworks as Selective and Reusable Catalysts for Glucose Isomerization to Fructose

AbstractFructose is a versatile precursor for food and chemicals. Currently, catalytic production of fructose is achieved by enzymatic isomerization of glucose from renewable lignocellulose. Although the catalyst, glucose isomerase, is selective, it is not stable. Here, aluminum‐containing metal‐organic frameworks (Al‐MOFs) are shown to be active, selective, stable, and reusable for glucose isomerization in ethanol. Al‐MOFs achieved 64% fructose selectivity with 82% glucose conversion at 120 °C, superior performance compared with most other solid catalysts. The amino groups in Al‐MOFs enhance Lewis acid strength, which is responsible for the high fructose selectivity at high glucose conversion. Moreover, the Al‐MOF catalyst is stable and reusable at least four times without losing either activity or fructose selectivity. These findings illustrate compelling opportunities for Al‐MOFs in fructose production and other organic reactions, such as fructose conversion to 5‐hydroxymethylfurfural and levulinic acid.

Electron-enriched Lewis acid-base sites on red carbon nitride for simultaneous hydrogen production and glucose isomerization

Glucose isomerization into fructose is a key process in industry for biomass valorization to produce value-added biofuels and biochemicals. Herein, considering the essential role of Lewis acid-base sites in proton transfer during glucose isomerization and hydrogen evolution process, a bifunctional polymeric red carbon nitride (PRCN) is rationally designed and fabricated by the salt-template-induced carbon incorporation strategy. The incorporation of carbon and potassium in the PRCN leads to the transient redistribution of photogenerated charges, acting as the electron-enriched Lewis base site and acid site for the deprotonation of O2-H and activation of aldehyde group of glucose, respectively. Besides, the interfacial Schottky junction boosts H2 production under visible light irradiation. This work demonstrates the feasibility of biomass photorefinery with H2 and value-added chemicals co-production under mild condition.

Production of high-yield 5-hydroxymethylfurfural from crystalline cellulose via one-pot conversion in molten salt hydrate/acetone and separation

5-hydroxymethylfurfural (5-HMF) is a crucial biomss-derived fuel precursor with versatile conversion pathways to advanced fuels. However, direct production of 5-HMF from crystalline cellulose is critical challenging due to the inefficient deconstruction of recalcitrant cellulose structure. Molten salt hydrates (MSHs) are unique in cellulose deconstruction and dissolution. In this work, a biphasic system of LiBr hydrate/acetone was established. It was found that 93.4% yield of 5-HMF can be efficiently converted from fructose without any catalysts. With the addition of AlCl3 to adjust Lewis acidity, an enhanced 5-HMF yield of 75.1% together with 13.7% of glucose were directly produced from cellulose, showing a promising carbon balance of 88.8%. A proposed mechanism for cellulose conversion was studied by density functional theory (DFT) calculations, demonstrating that the isomerization of glucose to fructose rather than crystalline cellulose hydrolysis was the rate-determining step. After reaction, the formed 5-HMF can be efficiently recycled from solvent via hyper-cross-linked polymer adsorption and the reaction system can be recycled for more than 5 times without reducing 5-HMF selectivity.

Oxygen affinity of transition metal cations: A coherent descriptor elucidating catalytic oxygenate transformations

This work reports a complementary descriptor to acidity for metal cations - oxygen affinity, to scale the interaction strength of metal cations with oxygenate groups. A method for measuring oxygen affinity is developed in alkyl methylimidazolium chloride solvents using in-situ far infrared (FIR) spectroscopy. The relative oxygen affinity values of metal cations in metal chlorides with model compounds including cyclopentanol (for alcohols), cyclohexanone (for ketones), ethylene glycol diethyl ether (for ethers), and H2O are measured from the dissociation kinetics of the metal-oxygenate complexes. The concentrations of metal-chloride and metal-oxygenate complexes are determined during evaporative removal of oxygenate molecules according to the FIR absorbance of metal-Cl bonds. The oxygen affinity values are shown to reasonably account for the catalytic performances of metal cations in furfural-acetone condensation and glucose isomerization reactions. The oxygen affinity descriptor could be potentially exploited as an intrinsic property of metal cation broadly for metal chloride or metal oxide.

Conversion of glucose to fructose over Sn and Ga-doped zeolite Y in methanol and water media

In this study, we use zeolite Y as a support for the synthesis of Sn and Ga doped zeolites aimed at the isomerization of glucose to fructose. Though these materials are inactive in water, they are active in methanol and we could ascertain a reaction pathway involving a hydride shift for the interconversion of glucose to fructose and mannose, and a Brønsted acid pathway with the formation of a methyl fructoside intermediate and its hydrolysis to fructose if water was added afterwards. By using characterizations comprising: chemisorption, XPS, XRD, HAADF-STEM and EXAFS; it was possible to demonstrate that a straightforward impregnation protocol for the preparation of our catalysts, led to Sn/Y mainly consisting of small SnO2 clusters on the external surface of the zeolite, whereas Ga/Y consisting of highly dispersed Ga species mostly inside the zeolite pores; and a catalytic activity that appears to be dominated by Brønsted acid sites.

Production of furfural and 5-hydroxymethyl furfural from Camellia oleifera fruit shell in [Bmim]HSO4/H2O/1,4-dioxane biphasic medium

The high-value utilization of Camellia oleifera fruit shell (CFS), which is an important waste in edible tea oil processing, is of great significance for the sustainable development of Camellia oleifera industry. In this study, the CFS after being simply pretreated (PCFS) to remove crude fat, pigment, et al., was used as material to produce furfural (FF) and 5-hydroxymethyl furfural (5-HMF) catalyzed by 1-butyl-3-methylimidazole hydrogen sulfate ([Bmim]HSO4). On the basis of comparing the superiority of microwave heating and traditional oil bath heating, on the basis of comparing the in-situ extraction of FF and HMF with four common solvents including 1,4-dioxane, methyl isobutyl ketone (MIBK), benzene, and cyclohexane, the [Bmim]HSO4/H2O/1,4-dioxane biphasic catalytic reaction system assisted by microwave irradiation was established. In this reaction system, FF was the chief product and 5-HMF was the chief by-product. The highest yields of FF and 5-HMF were 67.54 mol% and 20.97 mol%, respectively. The yield of FF was much higher than that of 5-HMF under the same reaction conditions. The kinetic analysis indicated that the hemicellulose hydrolysis to xylose catalyzed by [Bmim]HSO4 was the rate-limiting step in the production of FF. The cellulose hydrolysis to glucose and the subsequent isomerization of glucose to fructose were the rate-limiting steps in the production of 5-HMF. The rapid formation of other by-products was also one of the reasons for low yield of 5-HMF. [Bmim]HSO4 still performed excellent stability and catalytic activity after three times of cycles. FF with a purity of 95.26% could be obtained from the 1,4-dioxane phase under vacuum distillation. The relative contents of hemicellulose and cellulose and the crystallinity index of cellulose in PCFS residues decreased with the enhancement of reaction temperature and retention time. The biphasic medium used in this study was efficient for the production of FF from CFS.

One step synthesis of Mo-doped carbon microspheres for valorization corncob to levulinic acid

This work presents the catalytic valorization agricultural waste into levulinic acid over Mo-doped carbon microspheres (MoCMP) in γ-valerolactone/water solvents. The MoCMP with Brønsted and Lewis acid were synthesized by hydrothermal carbonization of uncrystallized cellulose with phosphomolybdic acid in one step, which was in absence of any additional modification. The MoCMP catalyst displayed a peak levulinic acid yield of 33.02% at 195 ℃ for 90 min. The improvement of Lewis acid sites was related by the Mo2C and Mo6+ species to promote the isomerization of glucose to fructose. The enhanced strong Brønsted acid sites were generated by carboxyl groups to facilitate the glucose dehydration to levulinic acid. MoCMP provided a high catalytic efficiency for production of LA from corncob. A simple and green method was proposed to synthesize Mo-doped carbon microspheres for valorization of agricultural biomass into valuable chemicals.

Investigation of cascade valorization of Pistia stratiotes L. by hydrothermal treatment

Aquatic plant Pistia stratiotes L. has widely dispersed around the world and is known for rapid reproduction in water system. However, over reproduction could generate serious issues such as clogging the waterways and results in secondary environmental pollution. Therefore, developing an economical and value-added route to valorize aquatic plants not only solves environmental pollution, but also provides novel utilization values. In this study, Pistia stratiotes L. was hydrothermal treated from 200 to 280℃, which can obtain hydrochar, light bio-oil and supernatant fractions. The surprising results showed that a large amount of alkali calcium (5.50 wt%) was enriched on the surface of hydrochar. And the hydrochar could be used as a catalyst for glucose isomerization to fructose after limited oxygen calcination. The yield of light bio-oil increases with the temperature and the composition contains a large amount of cyclopentene derivatives, which can be further refined to chemicals. The hydrothermal supernatant contains a large amount of calcium, magnesium, iron and other nutrients. The seed germination test showed that the supernatant liquid had certain bioactivity and had the potential of developing liquid fertilizer. This study provides basic reference for comprehensive and novel utilization of aquatic plants with abundant yield.

Síntesis benigna y sencilla de dímeros de tipo lignano usando peroxidasa cruda de rábano rojo (Raphanus sativus var sativus)

Nowadays, immobilized enzymes are utilized in several food industry applications. Some researches use apparent kinetic parameters in immobilized enzyme reactor systems, which are limited to such case studies. To enhance productivity in a packed bed reactor (PBR), a clear description of all the mechanisms (kinetic, intra-particle diffusive mass transport, fluid-particle convective mass transport, and axial dispersion) affecting the process should be established. The objective of this study was to model the isomerization of glucose in a PBR with calcium alginate beads (CAB), using an approach where the kinetic and diffusional mechanisms are described independently. The convective mass transfer (kL) and axial dispersion (Dz) coefficients were calculated from correlations. Validation was performed comparing predictions against experimental data (R2 = 0.907) of glucose conversion at the reactor’s outlet once steady state was reached. Under the study conditions, in contrast to the effect exerted by diffusive mass transport on fructose specific productivity, the effect of axial dispersion and convective mass transport is negligible. Analyzing different operation parameters via simulation, the particle size had the highest impact on the glucose bioconversion. By reducing the CAB size, the surface area is increased and thus the conversion. It is recommended to test new immobilizing agents or decreasing the CAB size, monitoring that immobilizing support preserves its stability and functionality.

Optimized HY via Thermal Modification as a Green Catalyst for One-Pot Synthesis of Fructose from Glucose Isomerization in Methanol/Water Medium

Optimized HY via Thermal Modification as a Green Catalyst for One-Pot Synthesis of Fructose from Glucose Isomerization in Methanol/Water Medium

Identification of Crucial Intermediates in the Formation of Humins from Cellulose-Derived Platform Chemicals Under Brønsted Acid Catalyzed Reaction Conditions.

Humins are one of the undesirable products formed during the dehydration of sugars as well as the conversion of 5-hydroxymethylfurfural (HMF) to value-added products. Thus, reducing the formation of humins is an important strategy for improving the yield of the aforementioned reactions. Even after a plethora of studies, the mechanism of formation and the structure of humins are still elusive. In this regard, we have employed density functional theory-based mechanistic studies and microkinetic analysis to identify crucial intermediates formed from glucose, fructose, and HMF that can initiate the polymerization reactions resulting in humins under Brønsted acid-catalyzed reaction conditions. This study brings light into crucial elementary reaction steps that can be targeted for controlling humins formation. Moreover, this work provides a rationale for the experimentally observed aliphatic chains and HMF condensation products in the humins structure. Different possible polymerization routes that could contribute to the structure of humins are also suggested based on the results. Importantly, the findings of this work indicate that increasing the rate of isomerization of glucose to fructose and reducing the rate of reaction between HMF molecules could be an efficient strategy for reducing humins formation.

The effectiveness of precipitation pH and temperature of Mg/Al Hydrotalcite synthesis on the glucose isomerization

Mg/Al Hydrotalcite as the catalyst in isomerization of glucose into fructose was made by coprecipitation of Mg(NO3)2.6H2O and Al(NO3)3.9H2O. Operating condition of precipitation including the temperature and pH was determined by Response Surface Method (RSM). The catalyst synthesis was carried out in the mole ratio of Mg/Al 3:1 for 18 h and the catalyst was activated by calcination for 3 h at 500°C. Catalyst characterization was done by FTIR, BET, and XRD. The highest mass product of Hydrotalcite Mg/Al 4.52 g, reached at the precipitation conditions of pH 9 and temperature of 45ºC. The catalytic activity of hydrotalcite Mg/Al was tested by the isomerization of Glucose into Fructose. The highest yield and selectivity were 20.14%, 62.40%, respectively. It was reached in pH 9 and 45ºC. While the highest conversion, 53.47%, was achieved in the pH 11.12 with a precipitation temperature of 45ºC. By the RSM analysis, neither the mass of catalyst product nor the catalytic activity from the isomerization (yield, conversion, and selectivity) were affected significantly by the pH and temperature precipitation.

Insights into the synergistic effect of catalyst acidity and solvent basicity for effective production of pentose from glucose

Controllable and effective transformation of glucose to high value-added products by regulating catalysts and solvents is significant and challenging. Herein, sodium lignosulfonate (SL) as a by-product of papermaking industry, was directly employed to convert glucose into pentose and formic acid (FA) with high efficiency due to the presence of both Lewis acid and weak Brønsted acid on the -SO3- group. The synergistic effect of catalyst and solvent on selective conversion of glucose to pentose, hydroxymethylfurfural (HMF) and furfural was innovatively revealed and it demonstrated that the product distribution can be regulated by varying the Brønsted acid strength and solvent basicity. The 13C-isotope labelling experiments suggested that glucose was firstly isomerized into fructose, the C1-C2 bond of which was then selectively breaking to form pentose and FA. Being consistent with the 13C-isotope experiment results, molecular dynamics simulation indicated that γ-butyrolactone-H2O (GBL-H2O) (19:1, w/w) changed SL arrangement around glucose predominantly to C1-OH and C6-OH, whose change contributed to the isomerization of glucose into fructose starting at C1-OH, and thus inhibited the dehydration of glucose to HMF starting at C2-OH, C3-OH and C4-OH. The degradation of pentose was also inhibited due to solvent regulation for SL distribution around glucose instead of pentose. The highest yield reached 86.5% pentose (60.2% xylose, 26.3% arabinose) and 93.1% FA with the aid of microwave (400 W, 413 K, 1 h). This strategy offered new insights into high-efficient production of platform chemicals from glucose and facilitated the green and sustainable development of modern bio-refinery and papermaking industry.