HMF Yield Research Articles

Hf-β zeolites as highly efficient catalysts for the production of 5-hydroxymethylfurfural from cellulose in biphasic system

In this work, a series of (x)Hf-β zeolite catalysts were prepared by a simple wet impregnation method and used as bifunctional catalysts with Lewis and Brønsted acid sites for synthesizing 5-hydroxymethylfurfural (5-HMF) from cellulose in H2O(NaCl)-THF biphasic system. Characterization analysis of (x)Hf-β zeolite catalysts with ICP-OES, N2 adsorption-desorption isotherm, XRD, FTIR, SEM, NH3-TPD and Py-FTIR indicated that the catalysts possessed favorable pore structure, appropriate acid strength and acidity. A superior 86.3 % cellulose conversion and 53.4 % 5-HMF yield could be obtained at 200 °C for 4 h by using (5 %)Hf-β zeolite as the catalyst. In addition, the catalytic system provided a favorable 5-HMF yield from other carbohydrates, including glucose (85.1 %), sucrose (80.6 %), starch (65.1 %), maltose (65.0 %), dextran (59.9 %), and Moso bamboo (21.9 %). Nevertheless, the recyclability of (5 %)Hf-β zeolite catalyst was unsatisfactory and the 5-HMF yield showed a downtrend from 53.4 % to 24.4 % after 5 cycles. The catalyst has promising potential for converting biomass materials into high-value platform compounds.

Introduction of acid mine drainage in the direct production of 5-hydroxymethylfurfural from raw biomass and expanding the use of biomass conversion residue

Direct production of 5-hydroxymethylfurfural (HMF) through biomass always needs the addition of exogenous catalysts and causes extra costs. Herein, acid mine drainage (AMD), one of the traditional wastewaters, was introduced as a natural catalyst to produce HMF directly from lignocellulosic biomass. Key factors in the biomass conversion were optimized and investigated by the response surface methodology (RSM), and the HMF yield reached 13.51 wt% under optimal conditions. The metal elements and the acidic environment in AMD activated the Fenton reaction to effectively destroy the lignocellulose structure and synergistically promote the formation of HMF. Furthermore, the biomass substrate in the biomass conversion was indirectly modified by the AMD during this process. The biomass conversion residue could be prepared by pyrolysis to obtain a functional metal-loaded carbon material with good adsorption of thiamethoxam (THX), which provides a sustainable solution for the disposal of biomass conversion residue.

Niobium and Zirconium Phosphates as Green and Water-Tolerant Catalysts for the Acid-Catalyzed Valorization of Bio-Based Chemicals and Real Lignocellulosic Biomasses

Commercial niobium and synthesized zirconium phosphates were tested as water-tolerant heterogeneous acid catalysts in the hydrothermal conversion of different bio-based substrates. Different acid-catalyzed reactions were performed using biomass-derived model compounds and more complex real lignocellulosic biomasses as the substrate. The conversion of glucose and cellulose was preliminarily investigated. Then, a wide plethora of raw lignocellulosic biomasses, such as conifer wood sawdust, Jerusalem artichoke, sorghum, miscanthus, foxtail millet, hemp and Arundo donax, were valorized towards the production of water-soluble saccharides, 5-hydroxymethylfurfural (HMF), levulinic acid (LA) and furfural. The different catalytic performances of the two phosphates were explained on the basis of their acid features, total acidity, Brønsted/Lewis acid sites ratio and strength. Moreover, a better insight into their structure–acidity relationship was proposed. The different acid properties of niobium and zirconium phosphates enabled us to tune the reaction towards target products, achieving from glucose maximum HMF and LA yields of 24.4 and 24.0 mol%, respectively. Remarkably, when real Jerusalem artichoke biomass was adopted in the presence of niobium and zirconium phosphate, maximum yields of furanic compounds and cellulose-derived sugars of 12.7 and 50.0 mol%, respectively, were obtained, after only 1 h of reaction. The synthesized hydrolysates, which were found to be rich in C5 and C6 carbohydrates, can be better exploited for the cascade production of more added-value bio-products.

One-pot synthesis of 5-hydroxymethylfurfural from cellobiose and sucrose using niobium-modified montmorillonite catalysts

The synthesis of platform chemical 5-hydroxymethylfurfural (5-HMF) provides favorable and efficient paths for the utilization of renewable biomass resources. In this work, highly active niobium-modified montmorillonite (Nb-Mont) catalysts were synthesized by a facile and ion-exchange method and were used for the one-pot conversion of cellobiose and sucrose to 5-HMF with optimal results. 5-HMF yield of 68.6% was obtained from cellobiose in a methyl isobutyl ketone (MIBK)/saturated salt water (SSW) biphasic solvent at 170 °C after 3 h. With sucrose as substrate in DMSO at 140 °C after 2 h, 5-HMF yield was 65.4%. The presence of Lewis and Brønsted acid sites on Nb-Mont facilitate the hydrolysis of cellobiose and sucrose and play essential roles in the subsequent isomerization of glucose monomer and the dehydration of fructose monomer. A possible reaction mechanism was proposed for the transformation of cellobiose and sucrose into 5-HMF, and the isomerization process of glucose monomer was the most critical step, confirmed by density functional theory (DFT) calculations. [NbO(OH)2]+ species as active sites could effectively reduce the activation energy of the isomerization process, which accelerated the synergetic proton transfer process. Nb-Mont was recycled at least four times without a prominent loss in the catalytic activity. In this study, a promising catalytic strategy was provided for heterogeneous Nb containing catalysts used in the effective synthesis of 5-HMF from carbohydrates.

Lignin-derived biochar solid acid catalyst for fructose conversion into 5-ethoxymethylfurfural

Lignin-derived biochar materials with acid functional groups (-COOH, –SO3H and –OH) were synthesized by carbonization of lignin (LigT) at T = (300, 400, 500) °C and mix ball-milling of the carbonized solids with thiomalic acid and partial oxidation of the functional solids with H2O2. Mix ball-milling promoted interactions between biochar CO and alkoxy C–O groups and thiomalic acid –COOH groups, which allowed H2O2 to convert covalently-bonded sulfur-containing functional groups on the biochars into Brønsted acid sites. The lignin-derived biochar solid acid materials were applied as catalysts to convert fructose into 5-ethoxymethylfurfural (EMF) and ethyl levulinate (EL) via 5-hydroxymethylfurfural (HMF) intermediate in ethanol solvent. Yields of HMF, EMF and EL reached 11%, 62% and 22%, respectively at 115 °C and 6 h with 100% conversion of fructose when the reaction was conducted with Lig300(S/C = 2)-SO3H, which had the highest total acidity in this work. The activation energy (70.9 kJ/mol) for conversion of fructose into HMF was lower than that for conversion of HMF into EMF (90.2 kJ/mol). The method for synthesizing sulfonated-containing biochars is green and efficient and the lignin-derived biochar solid acid catalysts are effective for converting renewable resources into platform chemicals.

An eco-friendly acidic catalyst phosphorus-doped graphitic carbon nitride for efficient conversion of fructose to 5-Hydroxymethylfurfural

An eco-friendly and stable metal-free acidic catalyst phosphorus-doped graphitic carbon nitride (P–UCN) synthesized for the highly efficient dehydration of fructose to 5-Hydroxymethylfurfural (HMF) was presented. The acidic sites (P sites) were introduced into the g-C3N4 structure via a simple thermal polycondensation of urea. A 91.7% HMF yield was achieved with optimal P–UCN catalyst under mild reaction conditions (160 °C, 3 h). XPS and NMR characterizations of P–UCN catalysts suggested that the P atoms may replace the corner and bay carbon sites, which could provide stable acidic sites for fructose dehydration into HMF. NH3-TPD analysis indicated that a moderate amount of P doped would provide higher catalytic activity for the dehydration reaction. Furthermore, the 1.0P–UCN (real content 1.83 wt%) catalyst was demonstrated high stability in the dehydration system and retained high reactivity after being recycled 5 times. The characterization results of recovered 1.0P–UCN further confirmed that the morphology and structure of the catalyst remained well after the dehydration reaction.

Effects of Acid Modulators on the Microwave-Assisted Synthesis of Cr/Sn Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) have attracted remarkable attention for their distinguished structural designability. Precisely controlling the particle size and improving the structural stability of MOF nanoparticles influence their catalytic activity significantly. In this study, six acids (nitric, hydrochloric, formic, acetic, succinic, and citric acids) were used as modulators to prepare bimetallic MIL-101 (Cr, Sn) (MIL stands for Materials of Institut Lavoisier) via a microwave-assisted hydrothermal method. Changes in volumetric, structural, stability, and catalytic properties, size, and shape of MIL-101 (Cr, Sn) were examined using scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and N2 adsorption–desorption measurements. All modulators altered the MOF properties. Compared with other samples, acetic acid as a modulator mildly altered the MOF morphology by narrowing their particle size distribution, enhancing the specific surface area, and significantly improving their water and thermal stabilities. The addition of acetic acid was suitable for the catalytic conversion of glucose to 5-hydroxymethylfurfural (5-HMF), achieving a 43.1% 5-HMF yield with 91.4% glucose conversion in a mixed solution of γ-valerolactone and saturated salt water at 150 °C after 30 min.

Multigram Synthesis of Pure HMF and BHMF.

5-Hydroxymethylfurfural (HMF) is a bio-based platform chemical that can be used as a building block to produce several compounds with diverse applications. Even though HMF synthesis holds promise for a greener future, the current state of technology and the high production cost limit its competitiveness on an industrial scale. In this prospect, we have developed a multigram-scale procedure for HMF by reacting d-fructose with Purolite CT275DR—an acidic resin—in a dimethyl carbonate (DMC)/tetraethyl ammonium bromide (TEAB) biphasic system. Reactions performed in an autoclave for 2 h at 110 °C using up to 40 gram of d-fructose resulted in an overall HMF yield of 70%. HMF was purified by a custom-made procedure leading to ca 50% of the pure crystalline product; meanwhile, the residual HMF-rich oil was directly reduced to bis(hydroxymethyl)furan (BHMF). Green metrics and the Ecoscale algorithm were used to evaluate the sustainability of the herein-proposed procedure in comparison with previously reported works.

Eco-friendly preparation of phosphated gallia: A tunable dual-acidic catalyst for the efficient 5-hydroxymethylfurfural production from carbohydrates

To develop an efficient catalyst/process for the production of 5-hydroxymethylfurfural (HMF), bifunctional phosphated gallia (GaP) catalysts were prepared by solid-state grinding, an eco-friendly method, and applied for glucose-to-HMF transformation. Strong Lewis (L) acid sites for isomerization of glucose-to-fructose were introduced by unsaturated Ga3+, while Bronsted (B) acid sites for dehydration of fructose-to-HMF were originated from P-OH group. The glucose-to-HMF process was optimized by response surface methodology to maximize the HMF yield. Complete glucose conversion and 65.72 ± 2.3% HMF yield were obtained at 175 °C, 2.75 h in THF/H2O biphasic-system. This catalytic performance can be attributed to the high surface area/porosity, sufficient total acidity, and well-balanced B/L acid sites of the GaP. Reusability/stability of the catalyst was demonstrated in 4 consecutive experiments. This catalyst also proved to be active in transforming other carbohydrates to HMF, obtaining ∼ 57%, ∼ 50%, and ∼ 31% yield with sucrose, starch, and cellulose, respectively.

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.

Postsynthetic acid modification of amino-tagged metal-organic frameworks: Structure-function relationship for catalytic 5-hydroxymethylfurfural synthesis

A hydrophobic acidic MOF is synthesized via the condensation of amino-tagged MOFs with mercapto carboxylic acids and subsequent oxidation. Developing an efficient and selective catalyst for the dehydration of fructose to 5-hydroxymethylfurfural (HMF) is significant for biomass conversion. Herein, a metal-organic framework (MOF) with acidity and strong hydrophobicity is first reported by the condensation of amino-tagged MOFs with mercapto carboxylic acids and subsequent oxidation. The hydrophobic acidic MOFs possess acid densities ranging from 0.2−1.0 mmol·g −1 , H 2 O contact angles of 114°−125°, and specific surface areas above 260 m 2 ·g −1 . Compared to the methyl sulfo-functionalized MOF, the benzene sulfo-functionalized MOF with a strong hydrophobicity shows much higher activity and selectivity for the conversion of fructose to 5-hydroxymethylfurfural. In particular, 2.99% (mass) UiO-PhSO 3 H shows the best catalytic performance with a 90.4% HMF yield due to its suitable hydrophobicity and abundant acidic sites. Moreover, the catalyst shows great stability after recycling for 5 runs. This work provides an interesting design strategy for the preparation of hydrophobic acidic MOFs and shows the powerful synergistic effect of acidity and hydrophobicity.

Effective Production of 5-Hydroxymethylfurfural from Fructose over a Highly Active Sulfonic Acid Functionalized SBA-15 Catalyst

Utilizing sugar compounds (such as fructose) as feedstock for conversion to HMF is very appealing, because it makes the production processes sustainable and improves the economic viability of platform molecules derived from biomass. Here, SBA-15 with sulfonic acid functionalization was created as a heterogeneous base catalyst for fructose hydrolysis reactions to create significant platform chemicals. A fructose conversion rate as high as 100%, along with a 78.7% yield of HMF, were obtained in DMSO at 130 °C after 1 h. The excellent catalytic performance of SBA-15-SO3H in fructose hydrolysis reactions was confirmed by the activation energy’s low value (56.99 kJ/mol). The mild conditions, fast rate of reaction, and simple operation are worth mentioning for other catalysts. SBA-15-SO3H has the potential to promote fructose conversion at lower temperatures.

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.

Synergistic catalytic effect of zirconium chloride and Brønsted acid salt for conversion of agarose to 5-hydroxymethylfurfural in aqueous media

A facile and highly efficient method for converting seaweed-derived agarose to 5-hydroxymethylfurfural (HMF) in aqueous media using combined metal salts as catalysts is proposed. A series of combined metal salts were investigated under different conditions. The combination of ZrCl4 and KHSO4 was the most efficient catalyst; it was capable of achieving a high HMF yield of 71.4% under optimized conditions. The charge density or counter anion possibly affected the ionization degree of the metal cations in the aqueous solution, thereby influencing the HMF yield. ZrCl4 promoted the cleavage of the C–O–C bond in agarose and galactose to ketose isomerization, which is the key step for HMF formation. KHSO4 increased the conversion rate of ketose to HMF. This work offers a convenient method for converting seaweed-derived agarose to HMF and improve the utilization of marine biomass.

Semisynthetic transformation of banana peel to enhance the conversion of sugars to 5-hydroxymethylfurfural

This study aimed to efficiently convert banana peels (BP) into 5-hydroxymethylfurfural (HMF) by using an integrated mechanoenzymatic/catalytic approach. There is no report on HMF production using mechanoenzymatic hydrolysis. Moreover, this method enables saccharification of lignocellulose without bulk solvents or pretreatment. The effects of the reaction volume, milling time, and reactive aging (RAging) on the mechanoenzymatic hydrolysis of BP were studied. The solvent-free enzymatic hydrolysis of BP under RAging conditions was found to provide higher glucose (40.5 wt%) and fructose (17.2 wt%) yields than chemical hydrolysis. Next, the conversion of the resulting monosaccharides into HMF in the presence of the AlCl3·H2O/HCl-DMSO/H2O system resulted in 71.9 mol% yield, which is so far the highest HMF yield obtained from cellulosic food wastes. Under identical reaction conditions, direct conversion of untreated BP to HMF yielded 22.7 mol% HMF, suggesting that mechanoenzymatic hydrolysis greatly promotes the release of sugars from BP to improve HMF yield.

Valorization of dairy by-products: Optimized synthesis of 5-hydroxymethylfurfural and levulinic acid from lactose and whey

Whey is a by-product of the dairy industry that has a high proportion of organic material. To valorize whey, the optimization of the synthesis of 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) from lactose and whey by utilizing a Brönsted acid as a catalyst was performed. The Box-Behnken statistical model was used to analyze and optimize reciprocal interactions between the reaction variables. As a result, 45.6% yield of LA from 0.3 M lactose and 0.6 M HCl catalyst/M substrate was achieved at a reaction temperature of 195 °C for 60 min. In addition, 25.4% yield of 5-HMF was obtained from 0.2 M whey (as lactose) and 0.3 M HCl/M substrate by heating it to 195 °C for 45 min. More 5-HMF was obtained from whey than lactose under identical reaction conditions. While lactose was converted more rapidly than whey to LA. A nonlinear sigmoid model producing high coefficient of determination values adequately explained the effects of combined severity factor levels on 5-HMF and LA yields from lactose. On the other hand, the case of whey was not well-matched with low R2 values. These findings imply that the use of lactose and whey as feedstocks for platform chemical synthesis will continue.

Dimethyl carbonate solvent assisted efficient conversion of lignocellulosic biomass to 5- hydroxymethylfurfural and furfural

An efficient, economic, and one-pot process has been developed for the direct conversion of untreated biomass feedstock such as corn-cob, sugarcane bagasse, rice-straw, and corn-straw into 5-HMF and furfural (FF) synthesis in dimethyl carbonate (DMC) solvent conditions under a pressurized hydrothermal steel vial system. The use of DMC as a green solvent under acidic medium was explored first time for the transformation of complex lignocellulosic biomass into furanic compounds. Moreover, the DMC solvent under acidic environment partially produced CO2 that facilitates the depolymerization of recalcitrant biomass substrate and subsequently participates in conversion under the set conditions. Notably, the influence of various parameters such as temperature, time, solvents, and the synergistic functions of AlCl3 and HCl was examined to optimize the reaction conditions. After optimization, the maximum yield of 5-HMF and furfural from various biomass feedstock was recorded as 35–60% and 61–98% respectively within 6 h at 180 °C. Furthermore, we have described the relative compositions of biopolymers (cellulose, hemicellulose, and lignin), moisture/and ash content in each biomass substrate. The SEM analysis provided information about particle size and shape via calculating aspect ratio of mechanical grinded lignocellulosic biomass. Subsequently, the quantification of products was scrutinized through UPLC and further reconfirmed via NMR and ESI-MS analysis techniques.

Synthesis and utilization of meso and microporous catalysts for the valorization of newspaper waste to bio-based chemicals using Choline chloride as biodegradable solvent

The present study develops an effective and sustainable catalytic system using mesoporous (KIT-6 and NbKIT-6) and microporous catalysts (ZIF-8) for the conversion of newspaper waste to value-added products such as TRS (Total reducing sugars) and 5-HMF (5-Hydroxymethyl furfural). The bio-based products were produced using green and biodegradable solvent Choline chloride in presence of sustainable catalysts under mild operating conditions at 1 atm pressure. The study demonstrated the potential of monophasic (Choline chloride and Catalyst) and biphasic (Choline chloride, Catalyst and Extracting solvent) system and revealed their comparative insights. It was observed that both the systems were highly effective but the purity and stability of products were higher in the biphasic system compared to the monophasic system. The synthesised catalysts possess high surface area 588.528, 534.414 and 351.85 m2/g with pore volume 0.7587, 0.3574 and 0.2362 cc/g for KIT-6, NbKIT-6 and ZIF respectively. The selected extracting solvents were found to be promising and the maximum 5-HMF yield was found to be 62.12%, 73.45% and 79.66% in DMSO medium using KIT-6 (160 °C, 135 min), NbKIT-6 (140 °C, 90 min) and ZIF-8 (140 °C, 105 min) catalysts respectively. Also, all the catalysts are reusable for up to five runs with minimal loss in catalyst activity. The proposed catalytic system will help to resolve the challenges associated with biorefineries in terms of product separation and recyclability of catalysts.

Titanium Phosphate Grafted on Mesoporous SBA-15 Silica as a Solid Acid Catalyst for the Synthesis of 5-Hydroxymethylfurfural from Glucose

The grafting of titania on SBA-15 followed by its phosphation was presented to prepare a mesoporous Lewis–Brønsted bifunctional solid acid catalyst for the tandem conversion of glucose via fructose to 5-hydroxymethylfurfural (HMF). Titania was dispersed on SBA-15 as an amorphous surface layer containing abundant coordinatively unsaturated tetrahedral Ti ions, which was reactive and readily transformed upon phosphation into a new titanium phosphate phase with the chemical formula identified as Ti2O3(H2PO4)2·2H2O. The ordered mesoporous structure was well maintained after three modification cycles, affording a desirable surface area of over 300 m2/g. The SBA-15-supported titanium phosphate layer affords higher overall acidity and Brønsted to Lewis acid ratio, compared with the conventional post-phosphated bulk anatase titania. The tetrahedral Ti ions and the adjacent protonated phosphate groups on the titanium phosphate layer could form Lewis–Brønsted acid pairs at molecular level proximity, which largely enhanced the selective tandem catalysis for glucose conversion via fructose to HMF. An optimized HMF yield of 71% was achieved at 160 °C in a water–methyltetrahydrofuran biphasic system over the SBA-15-supported titanium phosphate catalyst. The catalyst exhibited good hydrothermal stability with a rather limited silicon and phosphate leaching, and no distinct pore collapse or performance loss over three sequential reaction runs.

Preparation of Metal-Loaded ZSM-5 Zeolite Catalyst and Its Catalytic Effect on HMF Production from Biomass.

This research work presented the preparation of metal-loading ZSM-5 zeolite catalyst by loading Cu and Cr ions into the ZSM-5 zeolite particles using ion exchange method. Technical conditions of ion exchange processes were investigated to find suitable process for preparation of modified zeolite. The as-obtained zeolite catalyst was then applied for the transformation reaction of biomass-derived glucose into 5-hydroxymethyl furfural (HMF). Glucose hydrolysate that achieved from enzymatic hydrolysis of rice straw was used as feedstock for transformation reaction using Cu-Cr/ZSM-5 catalyst. This metal-loading zeolite exhibited good catalytic activity for lignocellulosic conversion to HMF, a valuable renewable green chemical. The content of loading metals in the zeolite catalyst affected significantly on the HMF yield. Moreover, the influence of transformation conditions such as solvent, temperature, catalyst dosage, and reaction time was investigated. According to the results, the optimum condition leading to the highest yield of HMF of 49.5 ± 0.5% was established. The as-prepared Cu-Cr/ZSM-5 zeolite catalyst showed impressive performance and can be considered a promising catalyst for the transformation of biomass-derived glucose to HMF.