The dehydration of fructose to 5-hydroxymethylfurfural efficiently catalyzed by acidic ion-exchange resin in ionic liquid

5-Hydroxymethylfurfural and its Downstream Chemicals: A Review of Catalytic Routes

Biomass assumes an increasingly vital role in the realm of renewable energy and sustainable development due to its abundant availability, renewability, and minimal environmental impact. Within this context, 5-hydroxymethylfurfural (HMF), derived from sugar dehydration, stands out as a critical bio-derived product. It serves as a pivotal multifunctional platform compound, integral in synthesizing various vital chemicals, including furan-based polymers, fine chemicals, and biofuels. The high reactivity of HMF, attributed to its highly active aldehyde, hydroxyl, and furan ring, underscores the challenge of selectively regulating its conversion to obtain the desired products. This review highlights the research progress on efficient catalytic systems for HMF synthesis, oxidation, reduction, and etherification. Additionally, it outlines the techno-economic analysis (TEA) and prospective research directions for the production of furan-based chemicals. Despite significant progress in catalysis research, and certain process routes demonstrating substantial economics, with key indicators surpassing petroleum-based products, a gap persists between fundamental research and large-scale industrialization. This is due to the lack of comprehensive engineering research on bio-based chemicals, making the commercialization process a distant goal. These findings provide valuable insights for further development of this field.

Dehydration of Xylose to Furfural over Imidazolium-Based Ionic Liquid with Phase Separation

An environmentally friendly catalyst and task-specific ionic liquid (IL), 1-(4-sulfonic acid) butyl-3-cetyl-2-methyl imidazolium hydrogen sulfate, was applied to the dehydration of xylose to furfural. Its structure was determined by FT-IR, 1H NMR technologies. The solubility of IL in water changed with the temperature, and had the advantages of homogeneous and heterogeneous catalysts. At the given conditions, xylose conversion of 95.3% and furfural yield of 67.5% were achieved over IL.

Pretreatment of lignocellulosic biomass: A review on recent advances

Depleting fossil reserves and growing energy needs have raised the demand for an alternative and clean energy source. The use of ubiquitously available lignocellulosic biomass for developing economic and eco-friendly large scale biorefinery applications has provided the much-needed impetus in this regard. The pretreatment process is a vital step for biomass transformation into added value products such as sugars, biofuels, etc. Different pretreatment approaches are employed to overcome the recalcitrance of lignocellulosic biomass and expedite its disintegration into individual components- cellulose, hemicellulose, and lignin. The conventional pretreatment methods lack sustainability and practicability for industrial scale up. The review encompasses the recent advances in selective physical and chemical pretreatment approaches such as milling, extrusion, microwave, ammonia fibre explosion, eutectic solvents etc. The study will allow a deeper understanding of these pretreatment processes and increase their scope as sustainable technologies for developing modern biorefineries.

Sugar dehydration to 5-hydroxymethylfurfural in mixtures of water/[Bmim]Cl catalyzed by iron sulfate

Stabilization effect of [Bmim]Cl on HMF is demonstrated, which can suppress the rehydration and polymerization side-reactions and enhance HMF yield.

Catalytic Transfer of Fructose to 5-Hydroxymethylfurfural over Bimetal Oxide Catalysts

Direct conversion of fructose into 5-hydroxymethylfurfural (HMF) is achieved by using modified aluminum-molybdenum mixed oxide (S-AlMo) as solid acid catalysts. The synthesized catalyst was characterized by powder XRD, nitrogen adsorption-desorption isotherm, NH3-TPD, and SEM. As a result, the presence of strong acidity, mesostructures, and high surface area in the S-AlMo catalyst was confirmed by nitrogen adsorption-desorption isotherm and NH3-TPD studies. A study by optimizing the reaction conditions such as catalyst dosage, reaction temperature, and time has been performed. Under the optimal reaction conditions, HMF was obtained in a high yield of 49.8% by the dehydration of fructose. Moreover, the generality of the catalyst is also demonstrated by glucose and sucrose with moderate yields to HMF (24.9% from glucose; 27.6% from sucrose) again under mild conditions. After the reaction, the S-AlMo catalyst can be easily recovered and reused four times without significant loss of its catalytic activity.

Efficient production of 5-hydroxymethylfurfural from fructose over CuAPO-5 molecular sieves synthesized using an ionothermal method

A group of CuAPO-5 molecular sieves with trace Cu were successfully synthesized via an ionothermal method and used for fructose dehydration to 5-hydroxymethylfurfural (HMF) in [BMIM]Br ionic liquid. The 0.06-CuAPO-5 sample displayed excellent performance and a HMF yield of 93.8% was obtained, which could be ascribed to the balance between acid strength and mass transfer efficiency. This work demonstrates that the ionothermal synthesized CuAPO-5 molecular sieve was also a good candidate for the efficient production of HMF.

The high yield of 5-hydroxymethylfurfural was achieved in the dehydration of fructose on the CuAPO-5 catalyst synthesized by the ionothermal method.

Catalytic Dehydration of Fructose to 5-Hydroxymethylfurfural (HMF) in Low-Boiling Solvent Hexafluoroisopropanol (HFIP)

A mixture of hexafluoroisopropanol (HFIP) and water was used as a new and unknown monophasic reaction solvent for fructose dehydration in order to produce HMF. HFIP is a low-boiling fluorous alcohol (b.p. 58 °C). Hence, HFIP can be recovered cost efficiently by distillation. Different ion-exchange resins were screened for the HFIP/water system in batch experiments. The best results were obtained for acidic macroporous ion-exchange resins, and high HMF yields up to 70% were achieved. The effects of various reaction conditions like initial fructose concentration, catalyst concentration, water content in HFIP, temperature and influence of the catalyst particle size were evaluated. Up to 76% HMF yield was attained at optimized reaction conditions for high initial fructose concentration of 0.5 M (90 g/L). The ion-exchange resin can simply be recovered by filtration and reused several times. This reaction system with HFIP/water as solvent and the ion-exchange resin Lewatit K2420 as catalyst shows excellent performance for HMF synthesis.

Microwave-Assisted Conversion of Fructose to 5-Hydroxymethylfurfural Using Sulfonated Porous Carbon Derived from Biomass

In this study, a series of sulfonated carbon solid acid catalysts was prepared by a template method using fructose as the carbon source and zinc chloride as the catalyst and template. The reaction involving fructose dehydration to 5-hydroxymethylfurfural (5-HMF) was investigated using these catalysts with microwave assistance in dimethyl sulfoxide. The influence of different catalysts, catalyst amount, microwave power, fructose content, and reaction temperature, as well as the reusability of the catalyst, were investigated. The prepared catalysts were characterised by X-ray diffraction, FT-IR spectroscopy, scanning electron microscopy, nitrogen adsorption–desorption measurement, and temperature-programmed desorption of ammonia gas, and the total numbers of surface acid sites of these carbon-based solid acid catalysts were analysed by chemical adsorption–desorption of ammonia along with the standard curve for ammonia. The results revealed that the C2-SO3H catalyst exhibited the best activity. A 5-HMF yield of 87 % and fructose conversion of 99 % were achieved at 170°C in DMSO after 3 min. The microwave-assisted synthetic strategy was advantageous compared with the traditional method because this approach could shorten the total reaction time.

Synthesis of a hierarchically porous niobium phosphate monolith by a sol–gel method for fructose dehydration to 5-hydroxymethylfurfural

A new type of niobium phosphate (NbP) with a hierarchically porous structure was synthesised via a sol–gel method accompanied by phase separation and effectively acted as a solid acid for fructose dehydration to HMF.

Acidic Zeolite L as a Highly Efficient Catalyst for Dehydration of Fructose to 5-Hydroxymethylfurfural in Ionic Liquid

Zeolite L was synthesized by the hydrothermal method and post-treated by NH₄ exchange to adjust its acidity. The samples were systematic characterized by various techniques including XRD, X-ray fluorescence spectroscopy, N₂ adsorption-desorption, scanning electron microscopy, pyridine IR spectroscopy, and NH₃ temperature-programmed desorption. The results demonstrated that the NH₄ -exchange post-treatment increased the surface area, micropore volume, and acidity of zeolite L. The catalytic performance of the samples was tested in the dehydration of fructose to 5-hydroxymethylfurfural (HMF) in ionic liquid (1-butyl-3-methylimidazolium bromide, [bmim]Br). 99.1 % yield of HMF was obtained when the KL-80 °C-1 h sample (KL zeolite treated with 1 m NH₄ NO₃ solution at 80 °C for 1 h) was used. The high efficiency could be attributed to the appropriate acid properties of the catalyst. The zeolite catalyst could be reused four times without significant decrease in activity.

Efficient dehydration of 6-gingerol to 6-shogaol catalyzed by an acidic ionic liquid under ultrasound irradiation

6-Gingerol and 6-shogaol are the main bioactive compounds in ginger. Although 6-shogaol has more and better bioactivities than its precursor 6-gingerol, the low content of 6-shogaol in ginger restricts its bioactive effects in functional foods. The traditional preparation methods of 6-shogaol are defective because of the environmental hazards and low efficiency of the processes. In this study, an efficient, easy and eco-friendly dehydration conversion of 6-gingerol to 6-shogaol is presented using an acidic ionic liquid 1-butyl-3-methylimidazolium hydrosulfate ([Bmim]HSO4) under ultrasound irradiation. The key parameters, including reaction temperature, reaction time, mass ratio of catalyst to substrate and ultrasonic power in each reaction process, were investigated. The yield of 6-shogaol reached as high as 97.16% under optimized condition. The catalyst could be separated from the reaction mixture and reused five times with only a slight loss of activity.

Synergy of Lewis and Brønsted acids on catalytic hydrothermal decomposition of carbohydrates and corncob acid hydrolysis residues to 5-hydroxymethylfurfural

5-hydroxymethylfurfural (HMF) is an important platform molecule in the synthesis of various chemicals and materials. Herein, we reported a simple and effective dehydration of glucose-based carbohydrates to HMF in a biphasic system containing cyclopentyl methyl ether as the organic phase and AlCl₃ with minute amounts of HCl as co-catalysts. The results showed that the mixed catalysts had a positive synergistic catalytic effect on glucose conversion to HMF compared with single AlCl₃ or HCl catalyst. For glucose, the highest HMF yield of 54.5% was achieved at 175 °C for 20 min. More importantly, the optimal catalytic system was so efficient that it achieved one of the highest reported yields of HMF (30.5%) directly from corncob acid hydrolysis residues. Thus, the catalytic system can become a promising route for effective utilization of biomass in future biorefineries.

p-Hydroxybenzenesulfonic acid–formaldehyde solid acid resin for the conversion of fructose and glucose to 5-hydroxymethylfurfural

SPFR solid acids. Novel solid acid resins were synthesized by an energy and time efficient hydrothermal method.

One-pot synthesis of 2,5-diformylfuran from fructose using a magnetic bi-functional catalyst

A magnetic bi-functional WO₃HO-VO(salten)-SiO₂@Fe₃O₄nanocatalyst was prepared to directly synthesize 2,5-diformylfuran (2,5-DFF) from fructose.

Critical design of heterogeneous catalysts for biomass valorization: current thrust and emerging prospects

Catalysis in the heterogeneous phase plays a crucial role in the valorization of biorenewable substrates with controlled reactivity, efficient mechanical process separation, greater recyclability and minimization of environmental effects.

Formation and reduction of 5-hydroxymethylfurfural at frying temperature in model system as a function of amino acid and sugar composition

5-Hydroxymethylfurfural (HMF) is formed during heat treatment of carbohydrate-containing foods, especially in a deep-fat frying process. This study aimed to investigate the effect of amino acids on the formation and reduction of HMF from glucose, fructose and sucrose at frying temperature in model systems containing binary mixtures of an amino acid and a sugar in equal concentrations (0.3M). The results revealed that the formation of HMF from sugars accelerated in the presence of acidic amino acids (i.e. glutamic and aspartic acids). Conversely, the presence of basic amino acids (i.e. lysine, arginine and histidine) led to reduced concentrations of HMF to non-detectable levels in model systems. The results showed that both pH and heating time significantly affected the formation of HMF from fructose in the presence of glutamic acid. In this regard, a higher amount of HMF was formed at lower pH.

Glucose dehydration to 5-hydroxymethylfurfural in ionic liquid over Cr3+-modified ion exchange resin

Cr³⁺-D001-cc resin shows excellent catalytic performance for the dehydration of glucose to 5-hydromethylfurfural, which is prepared by a simple ion-exchange method.

5-hydroxymethyl-2-furfural and derivatives formed during acid hydrolysis of conjugated and bound phenolics in plant foods and the effects on phenolic content and antioxidant capacity

A common protocol for the extraction of phenolic aglycons or bound phenolics in plants generally involves hydrothermal hydrolysis in an aqueous methanol or ethanol solution containing 2-4 N HCl. However, as shown in the present study, this process also forms 5-(hydroxymethyl)furan-2-carbaldehyde (HMF) and its derivative products 5-(methoxymethyl)furan-2-carbaldehyde (MMF) and 5-(ethoxymethyl)furan-2-carbaldehyde (EMF), as identified by HPLC-DAD-ESI-MS/MS and NMR. These compounds are commonly misidentified as phenolics due to similar UV absorption at 280 nm. In this study, production of HMF, MMF, and EMF was shown to be dependent on the solvent condition and duration and temperature of hydrolysis. Fruits and vegetables produced HMF more readily than grains. HMF and its derivatives were subjected to various spectrophotometric antioxidant assays [2-diphenyl-1-picryhydrazyl radical scavenging activity (DPPH), ferric-reducing antioxidant power (FRAP), and oxygen radical absorbing capacity (ORAC)] and displayed antioxidant activity mainly in the ORAC assay. Results of this study help avoid overestimation of phenolic content and antioxidant activities of plant foods.