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Efficient production of 5-ethoxymethylfurfural from fructose by sulfonic mesostructured silica using DMSO as co-solvent
Abstract
The use of sulfonic acid-functionalized heterogeneous catalysts in conjunction with the use of dimethyl sulfoxide (DMSO) as co-solvent in the catalytic transformation of fructose in ethanol to produce 5-ethoxymethyl furfural (EMF) is shown as an interesting alternative route for the production of this advanced biofuel. Arenesulfonic acid-modified SBA-15 mesostructured silica (Ar-SO3H-SBA-15) has been the most active catalyst, ascribing its higher catalytic performance to the combination of excellent textural properties, acid sites surface concentration and acid strength. Noticeably, DMSO promotes the formation of EMF and HMF, reducing the extent of side reactions. Reaction conditions (temperature, catalyst loading and DMSO concentration) where optimized for Ar-SO3H-SBA-15 via response surface methodology leading to a maximum EMF yield of 63.4% at 116 °C, 13.5 mol% catalyst loading based on starting fructose and 8.3 vol.% of DMSO in ethanol after 4 h of reaction. Catalyst was reused up to 4 consecutive times, without regeneration treatment, showing a slight gradual decay in activity attributed to the formation of organic deposits on the catalyst’s surface.
... rough the sulfonation modification of SBA-15, the catalyst Ar-SO 3 H-SBA-15 was prepared by Morales et al. [66]. A maximum EMF yield (63.4%) was obtained from fructose over Ar-SO 3 H-SBA-15 at 116°C for 4 h in a cosolvent system with ethanol and DMSO. ...
... It is indicated that the silica-SO 3 H catalyst which had Brønsted acid sites could carry out hydrolysis and etherification reactions but could not isomerize glucose. Morales et al. [66] successfully fabricated a sulfonic acid-functionalized catalyst (Ar-SO 3 H-SBA-15) by loading arene sulfonic acid on modified SBA-15 mesostructured silica. ey used response surface methodology to optimize the catalyst loading, temperature, and cosolvent concentration (DMSO) of reaction by Ar-SO 3 H-SBA-15. ...
... e addition of a suitable cosolvent under the same reaction conditions can significantly increase the EMF yield, and the commonly used cosolvents usually include DMSO, THF, and GVL. It was indicated that the additive of DMSO could promote the formation of EMF and reduce the formation of byproducts [66]. Zhang et al. [111] found that, under the same reaction system, the yield of EMF in the ethanol system was 43.7%, and when the solvent was changed to ethanol/DMSO (8 : 2), the yield of EMF was greatly improved to 78.9%. ...
A new generation of bioplatform molecule 5-ethoxymethylfurfural (EMF) has excellent energy density and combustion performance, which makes it a potential fuel additive. This article reviews the factors that affect the production of EMF from different feedstocks, including platform compounds, monosaccharides, polysaccharides, and raw lignocellulosic biomass. Focus is placed on discussing the catalytic efficiency with pros and cons of different acid catalysts, including homogeneous catalysts (i.e., liquid acids and metal salts), heterogeneous catalysts (i.e., zeolites, heteropolyacid-based hybrids, and SO3H-based catalysts), ionic liquids, mixed acid catalysts, and deep eutectic solvents (DESs). Except for the commonly used ethanol solvent, this review also summarizes the influence of the cosolvent system (e.g., ethanol/dimethylsulfoxide (DMSO), ethanol/tetrahydrofuran (THF), and ethanol/γ-valerolactone (GVL)) on the EMF yield.
... The most used catalysts in the etherification reactions are acid-catalysts, which are identified as the key point in this process [99]. Although some homogeneous acid catalysts have been proposed [101][102][103][104][105][106], the use of heterogeneous catalysts (heteropolyacids [107,108], their supported nanoparticles [109,110], acid-modified mesoporous silica materials [3,111], GO [112], zeolites and resins [113]) seems to be promising and more adequate in order to avoid the well-known disadvantages presented by homogeneous acid catalysts [114]. Recent studies have evidenced that the type and strength of the acid sites, as well as the operating conditions and the used cosolvent, influence the reaction path and the selectivity [111]. ...
... Although some homogeneous acid catalysts have been proposed [101][102][103][104][105][106], the use of heterogeneous catalysts (heteropolyacids [107,108], their supported nanoparticles [109,110], acid-modified mesoporous silica materials [3,111], GO [112], zeolites and resins [113]) seems to be promising and more adequate in order to avoid the well-known disadvantages presented by homogeneous acid catalysts [114]. Recent studies have evidenced that the type and strength of the acid sites, as well as the operating conditions and the used cosolvent, influence the reaction path and the selectivity [111]. ...
... Moreover, they suggest that the existing water in the reaction medium could significantly reduce the EMF yield. [111]. ...
The depletion of fossil resources in the near future and the need to decrease greenhouse gas emissions lead to the investigation of using alternative renewable resources as raw materials. One of the most promising options is the conversion of lignocellulosic biomass (like forestry residues) into bioenergy, biofuels and biochemicals. Among these products, the production of intermediate biochemicals has become an important goal since the petrochemical industry needs to find sustainable alternatives. In this way, the chemical industry competitiveness could be improved as bioproducts have a great potential market. Thus, the main objective of this review is to describe the production processes under study (reaction conditions, type of catalysts, solvents, etc.) of some promising intermediate biochemicals, such as; alcohols (1,2,6-hexanetriol, 1,6-hexanetriol and pentanediols (1,2 and 1,5-pentanediol)), maleic anhydride and 5-alkoxymethylfuran. These compounds can be produced using 5‑hydroxymethylfurfural and/or furfural, which they both are considered one of the main biomass derived building blocks.
... In the DMSO and DMSO-DMF (dimethyl formamide) mixtures (entries 3 and 16 through18), the mass rates of DMSO and DMF increased from 0:1 to 1:2 and 1:1 to 2:1, the HMF yield increased greatly from 2.81% to 33.07%, 45.23%, and 50.49%. The performance of DMSO might be attributed to its interactions with HMF via solation and high solubility for sugars (Dong et al. 2017;Morales et al. 2017;Dou et al. 2018). Note: the rates in brackets of entries 8 to 24 were the mass rates of the before and after compounds and all total masses were 2.5 g; IL was 1-butyl-3-methylimidazolium chloride. ...
... Hence, the main byproducts were unidentified, such as soluble polymers and insoluble humins. Although the structures and formation mechanisms of the unidentified were not explicit, numerous works have argued that the unidentified compounds could be ascribed to the polymerization of HMF and intermediate dehydration products of fructose, in which HMF primarily was a crossing-linking agent (Lane et al. 2016;Martínez-Vargas et al. 2017;Morales et al. 2017;Zhang et al. 2017). According to the results and conclusions, the possible reaction mechanism was proposed and shown in Fig. 9. Furthermore, it was also discovered from Fig. 8 that the conversion of glucose increased with the increased reaction times. ...
With the aim of developing an efficient and inexpensive catalyst for the production of HMF from glucose, a solid Lewis acid catalyst γ-AlOOH, a common industrial catalyst with easy preparation and low price, was used as the sole catalyst to directly synthesize 5-hydroxymethylfurfural (HMF) from glucose in dimethyl sulfoxide. Various reaction parameters, such as catalyst loading, temperature, reaction duration, and solvent, were investigated. An impressive HMF yield of 61.2% was obtained at the reaction conditions of 130 °C for 3 h. Furthermore, HMF yields from other carbohydrates such as fructose (44.8%), cellulose (50.3%), maltose (53.6%) and sucrose (62.2%) could be achieved using γ-AlOOH as a catalyst. More importantly, the catalyst γ-AlOOH could be reused several times without the loss of its catalytic activities. After five reaction runs, an HMF yield of 57.2% was obtained.
... 5, 6 5-ethoxymethylfurfural (EMF), as a representative of the 5alkoxymethylfurfural ether family, has the advantages of high energy density (8.7 kW h L À1 ), high cetane number, high boiling point (508 K), low toxicity, and good uidity at low temperature and can dramatically decrease sulfur dioxide and ne particle matter emissions. [7][8][9][10] Generally, EMF can be obtained by the single-step etherication of 5-hydroxymethylfurfural (HMF), the two-step dehydration-etherication cascade reaction of fructose, the three-step isomerization-dehydration-etherication cascade reaction of glucose, or synthesis from lignocellulosic biomass materials. 11,12 Among these, using HMF or fructose as raw materials to produce EMF can obtain relatively high yields. ...
... This could be ascribed to the fact that the introduction of DMSO can help the dehydration reaction and prevent the polymerization of intermediate products and the side reactions. 9 Nonetheless, a high concentration of DMSO would reduce the relative content of ethanol in the solvent system, thus slowing down the etherication rate of intermediate HMF, which is not conducive to generating EMF. 45 ...
Selective catalytic conversion of carbohydrates to 5-ethoxymethylfurfural (EMF) is a critical approach to the biorefinery. In this work, solid acid catalysts of γ-AlOOH and CeO2@B2O3 were used to convert carbohydrates to EMF in a one-pot process, performed in an ethanol/DMSO solvent system. The synergistic effect of γ-AlOOH and CeO2@B2O3 was studied. Furthermore, the morpho-structural properties of the catalysts were characterized, and the effects of reaction time, reaction temperature, catalyst load, and the amount of cosolvent on the conversion of glucose to EMF were examined and optimized. Under the reaction conditions of 170 °C for 20 h, glucose, sucrose, cellobiose, inulin and starch were used as raw materials, and the EMF yield range was 9.2-27.7%. The results showed that the synergistic effect of γ-AlOOH and CeO2@B2O3 further causes the combination of multiple acid sites with different types and strength distributions. Particularly, the collaboration between weak, medium-strong, and strong acid, as well as between Lewis and Brønsted acidity, is of great significance for EMF generation. The reusability experiments showed that the combined catalytic system was easily separated and maintained catalytic activity for five successive reactions without further intermediate regeneration steps. This work provides a promising route for the catalytic conversion of biomass-derived carbohydrates into EMF.
... As shown in Fig. 2, two pathways of ethyl fructoside (e.g., ethyl fructofuranoside, ethyl fructopyranoside) and HMF intermediate pathway may be the major production route for the production of EMF from fructose. Another research group (Morales et al., 2017) demonstrated through a factorial experiment design that catalytic system might play a pivotal role in choosing the EMF production pathway from fructose. Accordingly, it is thought that the choice of catalytic system could be a critical factor for more efficient production of EMF from fructose. ...
... EtOH; ethanol, EDFF; ethyl-D-fructofuranoside, EMF; ethoxymetylfurfural, HMF; hydroxymethylfurfural. Adapted from the references:(Flannelly et al., 2015;Morales et al., 2017). ...
2,5-Dimethyfuran (DMF) and ethoxymetylfurfural (EMF) are the emerging potential bio-based fuel candidates that can replace petro-based ones. These fuels possess physicochemical properties comparable to those required in gasoline engine performance, but they have more favorable properties than bioethanol. In current, two types of input substrates, hydroxylmethylfurfural (HMF) and fructose-based feedstocks are used to produce these fuel candidates due to their higher production efficiency. This bio-based production process has advantages in the sustainability point of view due to the low-carbon economy and resource renewability, but its economic issue is a significant roadblock in their industrial production mainly due to high production costs. Our proposed strategies afford significant information about their cost-effective production processes. One approach is to apply the direct conversion technology of inulin-rich raw plant biomass to these biofuels. Their direct use eliminates several processing steps required in the production process of both biofuels, contributing to reduction of their production costs The processes proposed can be performed in one-step processing systems consisting of 3–4 reaction elements: Feeding substrate, ionic liquid solvent, selected catalysts, and/or ethanol/additive. Their admixture is directly processed to the final products under the given reaction condition with no separation step of the major intermediates (e.g., HMF) occurring during the processing. The proposed strategies are less complicated and straightforward processes that have not been attempted before. Together with these strategies, bioengineering strategies are introduced for facilitating the efficiency of production processing and improving inulin content of the target plants, which can conduce to reducing their production costs.
... In rethinking aqueous-phase conversion routes for biomass-related compounds such as fructose, use of a non-aqueous solvent (ethanol) for conversion schemes with protonated polar compound additives could simplify the chemistry, because the 5-HMF intermediate is unstable in water and tends to undergo acid-catalyzed side reactions when water is present [9][10][11][12][13]. Use of ethanol as reaction solvent could allow fine control of the conversion steps and it would be possible to study of the stability of the 5-HMF intermediate and its further reaction to 5ethoxymethylfurfural (5-EMF) via etherification [14][15][16]. Furthermore, use of protonated polar additives rather than strong Brønsted acids would be desirable for making the conversion process sustainable and environmental, especially in regards to safety, product separation and recycle of catalyst. ...
... Results reported in the literature for other heterogeneous catalytic systems (Table S1) can be explained by the above mechanism for protonated polar additives. When conversion of fructose in ethanol with additive solvents (DMSO or 1,4-dioxane) is considered, 5-HMF can be efficiently synthesized (Entries 1-9, Table S1) [15,[30][31][32]. Catalytic conversion of fructose with homogeneous catalysts (e.g. ...
... SBA-X (Santa Barbara Amorphous) with thicker wall has become the most popular member of mesoporous silicas and possesses more chemical, thermal, and mechanical stability [20,21]. In particular, sulfonic acid functionalized SBA-15 have been widely investigated for HMF production from different carbohydrates [22][23][24][25][26][27][28]. Compared to SBA-15, which has channel-like ordered mesopores, SBA-16 with cage-like mesoporous framework was found to be more effective in some catalytic processes [29,30]. ...
Catalytic application of propylsulfonic acid modified mesoporous SBA-16 for 5-hydroxymethylfurfural (HMF) production was described for the first time. This material (SO3[email protected]) was produced by a simple two steps method involving the grafting of mercaptopropyl groups to SBA-16 and oxidation to sulfonic acid groups with H2O2. Using a combination of Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), and acid-base titration techniques, the successful immobilization of propylsulfonic acid groups on SBA-16 was assessed. In addition, X-ray diffraction (XRD), N2 adsorption–desorption isotherms, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses confirmed that the mesostructure of SBA-16 was preserved during the grafting of propylsulfonic acid groups. It was found that SO3[email protected] exhibited outstanding catalytic efficiency and recyclability in fructose conversion to HMF. Various reaction conditions were examined and high yield of HMF (91 %) was achieved after 60 min at 110 °C in DMSO/water (2:1, v:v).
... When methanol and ethanol were used, products 10 (MMF) and 11 (EMF), respectively, were obtained in moderate yields using AlCl 3 as catalyst. Ethoxymethylfufural 11 was also synthesized with a similar yield from fructose in ethanol, through a one-pot reaction strategy under microwave irradiation (Morales et al., 2017). Both etherification strategies generate the corresponding alkyl levulinate as the main by-product (12-20%), which cannot be separated by column chromatography. ...
Biomass-derived chemical platforms such as 5-hydroxymethylfurfural (5-HMF) can offer straightforward access to new value-added products. The presence of an aldehyde and hydroxymethyl functional groups in this molecule are interesting structural motifs to explore the synthesis of new bioactive compounds. In this contribution, a strategy to quickly and efficiently synthesize nitrovinylfurans starting from 5-HMF under greener conditions is described and the antiproliferative activity of the synthesized compounds evaluated. 5-HMF obtained by microwave-assisted saturated biphasic dehydration from fructose was used to produce furaldehyde derivatives. Next, through a nitroaldolic condensation, the desired nitrovinylfurans were generated using efficient heating sources, ultrasound, or a non-microwave instant heating reactor, under solvent-free conditions. Most of the newly synthesized compounds showed growth inhibition when assayed for their in vitro antiproliferative activity against six cancer cell lines (A549, HBL-100, HeLa, SW1573, T-47D, and WiDr), with lower toxicity on the human macrophage-like cells (THP-1). Our strategy allowed the rapid identification of nitrovinylfurans 16, 17, 19, and 20 as future candidates for the development of new selective anticancer drugs.
... Interestingly, the co-addition of organic solvents (tetrahydrofuran and dimethyl sulfoxide) or ionic liquids promote reaction rates and improve 5-EMF selectivity in such systems by inhibiting undesirable reactions (further ethanolysis, rehydration, and polymerization). 27,28 In this review, literature on the potential applications of 5-EMF, advantages of 5-EMF as a fuel blend, catalytic pathways of 5-EMF synthesis, mechanistic approaches for 5-EMF synthesis, sustainability assessment of synthesis methods, separation methods for 5-EMF, upgrading of 5-EMF into value-added chemicals, and current technologies for producing 5-EMF from biomass-derived compounds are described. Sustainability indicators (environmental, social, and economic) of reported reaction routes for 5-EMF systems show the preferred reaction routes. ...
Renewable resources must be upgraded to platform chemicals and biofuels, especially furanic compounds such as 5-hydroxymethylfurfural (5-HMF) and 5-ethoxymethylfurfural (5-EMF), to meet the needs of a sustainable society. This review examines chemocatalytic approaches to 5-EMF via alcoholysis of 5-(halomethyl)furfural or etherification of 5-HMF with attention being given to direct catalytic conversion of biomass-derived materials into 5-EMF. Emphasis is placed on the reaction mechanisms and pathways with either homogeneous or heterogeneous catalysts to provide recommendations for catalytic system development. A multicriteria assessment evaluation tool as a sustainability assessment method for the synthesis of 5-EMF routes from biomass is given. Potential research directions include the direct synthesis of 5-EMF from biomass-derived compounds in innovative reaction systems and technoeconomic studies on 5-EMF production.
... Furthermore, the use of EMF instead of fossils could also decrease soot and sulfur oxide emissions, which may have a positive effect in alleviating the air pollution [11][12][13]. Generally, EMF is synthesized through the classical reaction of etherification of 5-hydroxymethylfurfural (HMF) through an acidic catalysis manner [14][15][16][17][18]. Since the catalyst is the core part of the catalytic reaction, the key to achieve high HMF synthetic performance lies in the exploration of highly efficient acid catalysts. ...
The catalytic etherification of 5-hydroxymethylfurfural (HMF) with the waste ethanol into high-energy-density 5-ethoxymethylfurfural (EMF) has been considered as a promising way to simultaneously alleviate the energy crisis and environmental pollution. However, the energy consumption is rather high as the synthesis of EMF requires a high temperature to open the etherification reaction. Herein, we demonstrate a clever design and construction of acidified biomass-derived carbon quantum dots (BCQDs)-modified UiO-66-NH2 that is immobilized on cermasite (H+/BCQDs/UiO-66-NH2@ceramsite), which can use the IR light as driven energy and wasted ethanol to trigger the catalytic conversion of HMF into EMF. The temperature on the surface of the immobilized catalyst could reach as high as 139 °C within 15 min IR irradiation. Due to the aforementioned advantages, the as-prepared catalyst exhibited excellent IR-triggered catalytic performance toward EMF production, where the EMF yields and selectivity were as high as 45% and 65%, respectively. The high catalytic performance originates from the outstanding photo-to-thermal conversion by the introduction of BCQDs, as well as the strong interactions between BCQDs and UiO-66-NH2 that boosts the etherification reactions. The immobilization of catalyst on cermasite not only benefits catalyst recycling, but more importantly reduces catalyst loss during practical applications. The conceptual study shown here provides new viewpoints in designing energy-effective materials for the conversion of wastes into high-value-added resources.
... During the conversion of glucose to EMF, water may be produced due to dehydration and etherification, which makes the hydrolysis of HMF into LA inevitable in this system . Since the polar co-solvent limits the conversion of HMF to LA (Morales et al., 2017), such as dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and GVL, many studies add cosolvents to this system, which significantly inhibited the production of EL (Yu et al., 2018). The amount of cosolvent also affects the yield of EMF. ...
The conversion of biomass into high-value chemicals through biorefineries is a requirement for sustainable development. Lignocellulosic biomass (LCB) contains polysaccharides and aromatic polymers and is one of the important raw materials for biorefineries. Hexose and pentose sugars can be obtained from LCB by effective pretreatment methods, and further converted into high-value chemicals and biofuels, such as 5-hydroxymethylfurfural (HMF), levulinic acid (LA), γ-valerolactone (GVL), ethyl levulinate (EL), and 5-ethoxymethylfurfural (EMF). Among these biofuels, EMF has a high cetane number and superior oxidation stability. This mini-review summarizes the mechanism of several important processes of EMF production from LCB-derived sugars and the research progress of acid catalysts used in this reaction in recent years. The influence of the properties and structures of mono- and bi-functional acid catalysts on the selectivity of EMF from glucose were discussed, and the effect of reaction conditions on the yield of EMF was also introduced.
... Other catalysts such as deep eutectic solvents, 15 [BMIM] [HSO 4 ], 16 and Ar-SO 3 H-SBA-15 (ref. 17 ) have also been studied for the synthesis of EMF from hexose. While converting hexose to EMF has the advantage of being a low cost, one-pot process, direct synthesis of EMF from carbohydrates still has some disadvantages, such as a long reaction time, high catalyst loading, and low EMF yield. ...
Herein, we investigated catalytic potential of a functionalized porous organic polymer bearing sulfonic acid groups (PDVTA-SO3H) to the etherification of 5-hydroxymethylfurfural (HMF) to 5-ethoxymethylfurfural (EMF) under solvent-free conditions. The PDVTA-SO3H material was synthesized via post-synthetic sulfonation of the porous co-polymer poly-divinylbenzene-co-triallylamine by chlorosulfonic acid. The physicochemical properties of the PDVTA-SO3H were characterized by FT-IR, SEM, TG-DTG, and N2 adsorption isotherm techniques. PDVTA-SO3H had high specific surface area (591 m² g⁻¹) and high density of –SO3H group (2.1 mmol g⁻¹). The reaction conditions were optimized via Box–Behnken response surface methodology. Under the optimized conditions, the PDVTA-SO3H catalyst exhibited efficient catalytic activity with 99.8% HMF conversion and 87.5% EMF yield within 30 min at 110 °C. The used PDVTA-SO3H catalyst was readily recovered by filtration and remained active in recycle runs.
... The second method involves obtaining 5-ethoxymethylfurfural (EMF) by using chloromethylfurfural as an intermediate in the presence of Brønsted acid catalyst such as Ar-SO 3 H-SBA-15 [32]. Utilizing strong Brønsted acid forms ethyl levulinate which is major drawback of this method [33]. The third method, which is considered the most common method for the production of furfuryl alkyl ethers, involves immediate etherification of furan alcoholic group with aliphatic alcohols in the presence of Brønsted acid catalyst. ...
In this study, 5-hydroxymethylfurfural (HMF) was converted into several biofuel additives such as alkox-ymethylfurans (AMFs) and 2,5-bis(alkoxymethyl)furans (BAMFs) through two-step sequential hydrogenation and etherification reactions. In the first step, zinc-iron magnetic nanocatalyst supported on activated carbon (ZnO-Fe 3 O 4 /AC) was prepared for the selective hydrogenation of HMF into BHMF and 5-MFA via Meerwein-Ponndorf-Verley (MPV) reaction in three different hydrogen donor alcohols (ethanol, 1-propanol, and 1-butanol). The important physical properties of the catalyst such as crystallinity, chemical composition, morphology, reduction behavior, and surface area were studied by using several analytical techniques. The effect of hydrogenation parameters such as catalyst concentration, temperature, and time on the selectivity of (BHMF and 5-MFA), and HMF conversion were studied. The best hydrogenation results were obtained with 0.2 mmole HMF and 100 mg of catalyst at 200 • C for 12 h. In the second step, three commercial Brønsted acid catalysts were used to convert the hydrogenated products into alkoxymethylfurans (AMFs) and 2,5-bis(alkoxymethyl)furans (BAMFs). At the optimum etherification conditions (65 • C and 10 h), a spectrum of mono-, di-, and tri-ether compounds were obtained. The hydrogenation catalyst (ZnO-Fe 3 O 4 /AC) was recycled and used for five times without a remarkable reduction in its catalytic activity.
... It is urgent to convert renewable biomass resources into advanced biofuels, and platform chemicals, such as polyhydric alcohol, furan compounds, short-chain alkanes, organic acids, and their esters derivatives [1][2][3][4]. Among these biofuels, 5-ethoxymethylfurfural (EMF), as a promising transportation fuel and fuel additive, has been in a center of attention [5][6][7]. The energy density of EMF (30.3 MJ/L) is closed to that of gasoline (31.3 MJ/L) and diesel (33.6 MJ/L), and higher than that of ethanol (23.5 MJ/L) [8,9]. ...
Abstract Biomass-derived 5-ethoxymethylfurfural (EMF) with excellent energy density and satisfactory combustion performance holds great promise to meet the growing demands for transportation fuels and fuel additives to a certain extent. In this review, we summarized the relative merits of the EMF preparation from different feedstocks, such as platform chemicals, biomass sugars and lignocellulosic biomass. Advances for EMF synthesis over homogeneous (i.e. inorganic acids and soluble metal salts), heterogeneous catalysts (i.e. zeolites, heteropolyacid-based hybrids, sulfonic acid-functionalized catalysts, and others) or mixed-acid catalysts were performed as well. Additionally, the emerging development for the EMF production was also evaluated in terms of the different solvents system (i.e. single-phase solvents, biphasic solvents, ionic liquids, and deep eutectic solvents). It is concluded with current challenges and prospects for advanced biofuel EMF preparation in the future.
... Two routes are possible with probiotics beverage powder to EMF in the present reaction system (the reaction network is shown in Scheme 1): (a) hydrolysis of fructan in expired probiotics beverage powder produced fructose, fructose undergoes dehydration to HMF which is then etherified to EMF; or the parallel, (b) etherification of fructose forms ethyl fructoside which then further undergoes dehydration to EMF. The rehydration of EMF, and the esterification of levulinic acid (LA, formed via HMF rehydration) are the main possible pathways for EL production [35,36]. Our target product is EMF, which is an intermediate in the series of consecutive reactions. ...
Valorization of food waste into value-added fuels or chemicals is of considerable significance. Herein, an efficient catalytic approach was developed for transforming expired fructan-rich food (probiotics beverage powder, onion powder and garlic powder that have expired) into the biofuel, 5-ethoxymethylfurfural (EMF), via a carbonaceous solid acid synthesized by hydrothermal carbonization and sulfonation of restaurant food waste. The as-prepared restaurant food waste-derived carbonaceous solid acid catalyst (FW-SO3H) was well-characterized by a series of model physical and chemical technologies, and its catalytic performances were evaluated by the ethanolysis of expired fructan-rich food for EMF synthesis. The effects of reaction process variables were investigated. A considerable EMF yield of 52.1% from expired probiotics beverage powder was obtained in DMSO/ethanol medium at 140 °C for 4 h. EMF yields of 20.4% and 11.7% were achieved from expired onion powder and expired garlic powder, respectively. This work provides a valorization strategy for both expired fructan-rich food and restaurant food waste.
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Synthesis of micro‐mesoporous zeolite composite with optimum micro and mesoporosity is an emerging research area due to its wide applications, especially in bulk chemical or biomass transformations. It offers advantages in preserving zeolite crystallinity, creating mesoporosity and converting bulky molecules into valuable products. This work presents the process of preparing bimodal micro‐mesoporous ZSM‐5 using dual templates (CTMABr and TPABr). XRD, N 2 adsorption–desorption, SEM, TEM, ²⁹ Si, and ²⁷ Al NMR were used to analyze the two‐dimensional micro‐mesoporous ZSM‐5. One‐step synthesis of bimodal micro‐mesoporous ZSM‐5 features dual micro/mesoporosity by a marginal decrease in the crystallinity (71%). Micro‐mesoporous ZSM‐5 composite was found to be dependent on the optimum CTMABr/SiO 2 molar ratio of 0.04 to 0.06. The micro‐mesoporous ZSM‐5 zeolite composite was evaluated for cascade synthesis of 5‐EMF (methoxymethyl furfural‐ biofuel additive) from fructose and exhibited a five fold increase in 5‐EMF yield to 24.2% as compared with parent ZSM‐5 (4.6%).
Recently, levulinic acid as an important bio-based platform compound has attracted wide attention, and its potential application value is very high. This article focuses on chem-catalytic produced ethyl levulinate (EL) from biomass-derived carbohydrates (C6 carbohydrates) via multiple reaction pathways, which has an energy density comparable to gasoline and has great potential as a fuel additive. This review focuses on recent examples of the synthesis of EL from various materials using homogenous or heterogeneous catalysts. Special emphasis is placed on the understanding of the reaction mechanism and pathways. This review also summarizes the future opportunities and challenges associated with the applications of EL as a fuel additive and in other fields.
Realising sustainability within the chemical industry necessitates a shift from the traditional linear approach, based on crude oil, to a circular economy using alternative feedstock such as biomass, from which 5-hydroxymethylfurfural (HMF) is a potentially highly interesting platform chemical. While its production is relatively straightforward via the dehydration of fructose, derived from either saccharides or lignocellulosic biomass, its production is hindered by undesirable side reactions, which decrease the selectivity of the intended reaction to HMF, hence diminishing the overall yield. Here we report a green, highly selective approach to producing 5-hydroxymethylfurfural (HMF) from fructose based on the co-deployment of a biphasic reaction medium, microwave radiation, and a commercial solid acid catalyst (FAU Y zeolites). Following an initial evaluation of catalyst–solvent interactions and diffusion, a hierarchical mesoporous Y zeolite was chosen and deployed within a range of reaction media and process conditions for process optimisation, identifying a biphasic system consisting of ((6 : 4 water : DMSO)/(7 : 3 MIBK : 2-BuOH)) as the optimal reaction medium. This solvent combination facilitated an HMF yield of ∼73.9 mol% with an excellent selectivity of ∼86.1% at 160 °C after only 45 minutes under microwave irradiation. These, in turn, result in optimal energy efficiency and excellent green credentials relative to conventional heating.
Lignin-derived biochar materials with acid functional groups (-COOH, –SO3H and –OH) were synthesized by carbonization of lignin (LigT) at T = (300, 400, 500) ºC 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 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.
Ethoxymethylfurfural (EMF) is a promising fuel additive and biofuel which can be produced via catalytic direct alcoholysis of fructose. In this work, microwave-responsive catalysts were prepared by carbonization of cellulose (via either hydrothermal treatment or calcination) then functionalized with SO3H group (via impregnation using concentrated sulfuric acid), which exhibit remarkable performances in one-pot catalytic conversion of fructose to EMF with ethanol. After a 8 h reaction under microwave irradiation at 75 °C, about 80.3% fructose conversion was achieved with the EMF yield of 61.2% for the carbon catalyst prepared by the hydrothermal treatment, which is much higher than that achieved by the catalysis promoted by conventional heating. Further investigation showed that with a microwave-responding catalyst, microwave irradiation encourages the formation of local hot-spots on the catalyst surface, thus facilitating the collision of reactant molecules with catalysts to improve the catalytic efficiency. This work demonstrates the potential of microwave-responsive heterogeneous catalysts for process intensification of valorization of bio-derived chemicals under microwave irradiation.
The catalytic transformation of biomass derived compounds into valuable liquid fuels has received considerable attention in past years. In this work, a sulfonic acid grafted halloysite nanotubes (HNTs-SO3H) was facilely...
The tautomer structure of monosaccharides plays an important role in its conversion and utilization, which is mainly manifested in the selectivity of the product and the reaction mechanism. The tautomer distributions of N-acetyl-d-glucosamine (GlcNAc), a natural nitrogen-containing monosaccharide were investigated by quantitative ¹H NMR (¹H qNMR) and ¹³C NMR (¹³C qNMR) at 298 K under the condition commonly utilized for biorefinery. Catalysts used for biorefinery, i.e. BaCl2, KCl, ZnCl2, MgCl2, B(OH)3, SnCl4•5H2O and amino acid ionic liquid were introduced into D2O or DMSO-d6 to explore the tautomer distributions of GlcNAc. The introduction of ZnCl2 and SnCl4•5H2O promoted the conversion of α-pyranose to β-pyranose. The introduction of amino acid ionic liquid has little effect on the percentage of tautomers in D2O. However, when the amino acid ionic liquid, such as [Thr]Cl, was introduced into DMSO-d6, the proportion of β-pyranose increased to 29.06%, compared with no catalyst introduced. Besides, we also studied the tautomer distributions of GlcNAc in commonly utilized reaction solvents for biorefinery, such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidinone, ethylene and glycerol. In these solvents, the proportion of β-pyranose in N,N-dimethylformamide and glycerol was reduced to 25.84% and 38.38%, respectively. This study provides the basic experimental data of tautomer distributions of GlcNAc, and guided the conversion and utilization of GlcNAc in the future.
Hydrothermal liquefaction (HTL) as a waste management technology has been investigated to produce renewable bio-crude and other valuable products from wet biomass and bio-waste. However, carbohydrates as a vital component in biomass have shown to increase the complexity of the process. Undesirable solid yields produced by the carbonisation/re-condensation of reactive carbohydrate intermediates could limit the renewable crude yield and recovery. In the present study, the reaction mechanism and kinetic models for the HTL of monosaccharides and polysaccharides are investigated using gas chromatography–mass spectrometry (GC–MS) and high-performance liquid chromatography (HPLC) to characterise, validate and quantify the most abundant organic species in the aqueous phase. The experimental data and models presented provide an unbiased understanding of the carbohydrate decomposition during HTL conversion, while the analysis of solid products clarifies solid transformations and integrates both phases into a more comprehensive reaction mechanism approach, including a shrinking core model for cellulose. Finally, ethanol and acetic acid were added as co-solvents to elucidate the effects of a fully renewable hydrogen donor solvent system to generate 5-ethoxymethyl furfural and ethyl levulinate (validated with GC–MS), two renewable fuel additives and promising tunable monomers candidates. Experiments were conducted with glucose, fructose, and cellulose in a batch reactor with 20% by mass premixed feedstock at 250 ◦C and 300 ◦C.
The transformation of aldose-based carbohydrates into 5-ethoxymethylfurfural (EMF) is very challenging as compared to ketose-based carbohydrates, but the formers are more abundant and cheaper. Here, a series of sulfated complex metal oxides were synthesized for the conversion of aldose-based mono-, di-, and poly-saccharides, as well as starchy food waste into EMF. The catalysts were carefully characterized and the results showed that the type and strength of the acid sites were more important than their concentration. It was also shown that the efficiency of these catalysts was significantly affected by the metal species in the catalyst composition and followed the order tetra- > tri- > bi- > mono-component metal oxides based catalyst. Among the prepared catalysts, Zr-Sn-Fe-Al-O-S exhibited superior catalytic activity, with an EMF yield of 33.1 % from glucose, and yields ranging from 4.1 - 26.3 % for di-, poly-saccharides and starchy food waste in ethanol/dimethyl sulfoxide solvent system under glucose/catalyst mass ratio of 4. The role of co-solvent in the reaction pathway was also studied. It was found that the predominant reaction pathway for EMF production was closely related to the co-solvent amount. A kinetic model of glucose conversion to EMF was developed and the thermodynamic analysis was performed, the main features of the experimental observations can be described by the model. Zr-Sn-Fe-Al-O-S was reused for four runs without intermediate regeneration steps, showing a slight decay in activity. After reactivation by calcination before the fifth cycle, the catalyst recovered its activity, indicating good reusability and thermal stability.
We report a sulfonated hydrophobic mesoporous organic polymer (MOP-SO3H) as a highly efficient heterogeneous catalyst for one-pot 5-ethoxymethylfurfural (EMF) production from fructose in ethanol solvent. MOP-SO3H was fabricated by co-polymerization of divinylbenzene (DVB) and sodium p-styrene sulfonate (SPSS) followed by ion exchange with dilute H2SO4, and its pore structure and acid density could be tuned easily by varying the mole ratio of SPSS to DVB. 31P MAS NMR analysis using trimethylphosphine oxide as a base probe molecule indicated that MOP-SO3H possessed a weaker Brønsted acid site than conventional cation-exchange resins. The superhydrophobic properties of MOP-SO3H were retained even after incorporating a greater number of sulfonic acid groups into the polymer framework, while conventional solid acid resins exhibited hydrophilic properties. MOP-SO3H exhibited a superior catalytic performance in comparison with conventional acid resins, a mesoporous acid catalyst, and homogeneous acid catalysts in EMF production from fructose. After optimization of various reaction conditions using MOP-SO3H, a high EMF yield of 72.2% at 99.3% fructose conversion was achieved at 100 °C in a very short reaction time of 5 h. Notably, MOP-SO3H showed a much higher EMF formation rate than the Amberlyst-15 catalyst (53.5 vs. 6.1 μmol g-1 min-1). This superior performance of the MOP-SO3H catalyst was attributed to its unique feature of large surface area containing a large quantity of readily accessible acid sites distributed throughout the hydrophobic polymer framework. In addition to its high catalytic activity, the notable stability of the MOP-SO3H catalyst was also confirmed by leaching and recyclability tests. Thus, owing to its excellent catalytic performance and easy scalability, MOP-SO3H can potentially be used as an industrial heterogeneous catalyst to produce EMF from various fructose-containing biomass.
This chapter compiles the main biofuels produced from lignocellulosic biomass. It discusses their physicochemical properties and the catalysts employed in their production. The lignocellulosic biomass is mainly composed of polymeric carbohydrates (cellulose and hemicellulose) and aromatic polymer lignin with smaller amounts of pectin, proteins, and inorganic salts. The composition of hemicellulose, cellulose, and lignin in lignocellulosic biomass is 25–35%, 40–50%, and 15–20%, respectively. A wide variety of biofuels can be obtained by using lignocellulosic biomass as feedstock. Biofuels such as bioethanol, biobutanol, biohydrogen, or biomethane have been largely studied in the literature, and they are produced via bioconversion processes from lignocellulosic biomass. However, other biofuels can be produced by chemical transformation using lignocellulosic biomass as sustainable low‐cost feedstock. The chapter discusses recent advances in procedures to obtain different furanic‐derived fuels including 5‐ethoxymethylfurfural, ethyl levulinate, 2,5‐dimethylfuran, 2‐methylfuran, and γ‐valerolactone.
As a very promising biofuel or fuel additive, the synthesis of 5-ethoxymethylfurfural (EMF) directly from renewable carbohydrates is an important biomass transformation process. Herein, a novel bifunctional catalyst has been successfully synthesized via a Pickering high internal phase emulsion (HIPE) template and pore-filled strategy and employed for the production of EMF from glucose in a one-pot manner. Catalytic results indicated that the grafted Cr³⁺ by the atom transfer radical polymerization (ATRP) method smoothly processed the isomerization of glucose to intermediate fructose and that the accessible -SO3H and Cr³⁺ active sites coexisted in the obtained bifunctional catalyst possessing synergistic effects. A high EMF yield of 48.1% was achieved under optimal reaction conditions in an ethanol/tetrahydrofuran (THF) medium. Besides, employing inulin, sucrose, cellobiose, maltose, and starch as the starting materials excellent EMF yields were also obtained over the developed bifunctional catalyst. This study offers new insights into the design of functional catalysts anchoring desirable active sites, and also highlights their applications for biomass transformation.
In this paper, sulfonic groups functionalized annealed bio-based carbon microspheres loaded polytetrafluoroethylene (A-BCMSs-SO3[email protected]) fibers with high activity, high stability, and easy regeneration were successfully fabricated by a simple method using low-cost raw materials. The characterization results showed that the annealed biomass carbon microspheres derived from waste Camellia oleifera shells were evenly distributed on the polytetrafluoroethylene fibers and the sulfonic groups can be successfully loaded on the surface of annealed biomass carbon microspheres by room temperature sulfonation. Subsequently, the as-prepared A-BCMSs-SO3[email protected] fibers were applied to the acid-catalyzed synthesis of liquid biofuel 5-ethoxymethylfurfural. The catalytic experiment results indicated that the annealing temperature and time during catalyst preparation have a significant effect on the activity and selectivity of A-BCMSs-SO3[email protected] fibers. The results of catalytic reaction kinetics showed that the yield of 5-ethoxymethylfurfural can reach more than 60% after 72 h of acid-catalyzed reaction. The stability test showed that the as-prepared A-BCMSs-SO3[email protected] fibers still maintained a stable acid catalytic activity after four recycles.
Dehydration followed by alcoholysis of glucose/fructose to 5-ethoxymethylfurfural (EMF) was carried over SBA-15 supported tin modified heteropoly silicate (SnSTA) catalysts. The physico-chemical properties of the catalysts were employed by X-ray diffraction, Fourier-transform infrared spectroscopy (FT-IR), pyridine adsorbed FT-IR, Transmission electron microscopy (TEM), N2-physisorption, Laser Raman and NH3-temperature programmed desorption techniques. Characterization results confirmed that Sn exchanged STA species have been productively embedded inside SBA-15 pores without disturbing parent hexagonal structure. The high conversion and selectivity towards EMF was achieved with 20 wt% Sn0.75STA on SBA-15. The catalyst high activity is accountable to well disperse intact Keggin Sn0.75STA on support, which led in generation of sufficient Bronsted and Lewis acidic sites. Influence of various reaction parameters for instance catalyst weight, reaction temperature, time were studied along with the stability and reusability.
Efficient synthesis of promising biofuel 5-ethoxymethylfurfural (EMF) directly from starch was developed over a mixed-acid system composed of Al2(SO4)3 and H3PO4 in ethanol−DMSO co-solvent medium. The reaction proceeds through the depolymerization of starch to form glucose over Brønsted acidic H3PO4, which is then isomerized to fructose by Al2(SO4)3, a Lewis acid catalyst. The mixed-acid system then synergistically catalyzes the formation of EMF. At 170 °C, 36.9%, 39.8%, and 34.7% yields of EMF can be captured from corn starch, amylose and amylopectin, respectively. Moreover, the conversion of cellobiose and wood pulp cellulose produces 38.5% and 9.5% yields of EMF.
Increasing energy demand and various problems associated with fossil fuels such as environmental pollution, global warming and diminishing petroleum reserves have greatly stimulated production of fuels and chemicals from renewable sources. Lignocellulosic biomass has been considered as one of the potential sources for a variety of fuels and industrial chemicals. 5-Hydroxymethylfurfural (HMF) has been identified as an excellent platform molecule because it is a flexible intermediate for the synthesis of bio-renewable fuels and materials. HMF can be easily obtained from acid-catalyzed hydration of biomass-derived carbohydrates (hexoses) in various media. HMF can be converted to energy products such as 2,5-bis(alkoxymethyl)furans (BAMFs), monomers for high-value polymers such as 2,5-bis(hydroxymethyl)furan (BHMF), and valuable intermediates for fine chemicals. Recently, magnetic nanoparticle based catalysts attracted more attention due to their good stability and easy separation from the reaction mixture by a permanent magnet. This unique magnetic separation property makes MNPs more effective than conventional filtration or centrifugation as it prevents loss of the catalyst.
This dissertation work focuses on, firstly, studying the effectiveness of silica coated magnetite (Fe3O4) nanoparticles MNPs supported with sulfonic acid groups (Fe3O4@SiO2-SO3H) on the dehydration of glucose to HMF. Secondly, preparing a cost-effective catalytic transfer hydrogenation system for the selective transformation of HMF into BHMF via Meerwein-Ponndorf-Verley (MPV) reaction over the copper iron magnetic catalyst supported on activated carbon in ethanol solvent with the absence of molecular hydrogen. Thirdly, producing alkoxymethylfurans (AMFs) which are considered a potential biofuels by using two-step sequential reactions with cheap heterogeneous zinc-iron oxides magnetic nanocatalyst for the hydrogenation of HMF to furfuryl alcohols in various alcohols solvents in the absence of molecular hydrogen followed by solid Brønsted acid catalyst for the etherification reaction of furfuryl alcohol derivatives. All prepared heterogeneous catalysts were characterized by FTIR, XRD, H2-TPR, XPS, ICP-OES, HRTEM-EDX, and N2 adsorption-desorption isothermal analyses (BET and BJH) and were tested for recyclability. The chemical products were identified by high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), and products quantities were calculated by using calibration curves of chemical standards. Various reaction conditions such as reaction temperature, reaction time, catalyst amount, and alcohol type were optimized.
In this work, catalytic transformation of sugar into 2-Formyl-5-ethoxymethylfuran (EMF) was studied using Zn-trapped sulfonated carbon (SO3H-Zn-SC) catalyst. The catalyst was easily prepared via impregnation-pyrolysis and sulfonation. The physical and chemical properties of as-prepared catalyst were tested and discussed in details. For upgrading experiment, EMF synthesis from glucose transformation via isomerization, dehydration and etherification processes was performed using ultrasonic system. The increasing of ultrasonic power and ultrasonic duty cycle promoted the formation of EMF product, providing a maximum EMF yield of 97.8%. The ultrasonic application promoted the selectivity for EMF formation at shorter-faster reaction rate. Moreover, SO3H-Zn-SC also exhibited good reusability with low amount of acid leaching in each cycle. This research provided alternative way for improving the yield of EMF at short reaction time.
Heterogeneous catalysis plays a key role in promoting green chemistry through many routes. The functionalizable reactive silanols highlight silica as a beguiling support for the preparation of heterogeneous catalysts. Metal active sites anchored on functionalized silica (FS) usually demonstrate the better dispersion and stability due to their firm chemical interaction with FSs. Having certain functional groups in structure, FSs can act as the useful catalysts for few organic reactions even without the need of metal active sites which are termed as the covetous reusable organocatalysts. Magnetic FSs have laid the platform where the effortless recovery of catalysts is realized just using an external magnet, resulting in the simplified reaction procedure. Using FSs of multiple functional groups, we can envisage the shortened reaction pathway and, reduced chemical uses and chemical wastes. Unstable bio‐molecules like enzymes have been stabilized when they get chemically anchored on FSs. The resultant solid bio‐catalysts exhibited very good reusability in many catalytic reactions. Getting provoked from the green chemistry aspects and benefits of FS‐based catalysts, we confer the recent literature and progress focusing on the significance of FSs in heterogeneous catalysis. This review covers the preparative methods, types and catalytic applications of FSs. A special emphasis is given to the metal‐free FS catalysts, multiple FS‐based catalysts and magnetic FSs. Through this review, we presume that the contribution of FSs to green chemistry can be well understood. The future perspective of FSs and the improvements still required for implementing FS‐based catalysts in practical applications have been narrated at the end of this review.
This study uses numerical modeling to provide a mechanistic discussion of the synthesis of the advanced biofuel candidates, ethyl levulinate and 5-ethoxymethylfurfural, from α/β-d-fructopyranose (d-fructose) in a condensed phase homogeneous ethanol system at 351 K catalyzed by hydrogen cations. A mechanistic comprehension is pursued by detailed measurements of reactant, intermediate, and product species temporal evolutions, as a function of H2SO4 (0.09, 0.22, and 0.32 mol/L) and d-fructose (0.14, 0.29, and 0.43 mol/L) concentrations, also considering the addition of water to the ethanol media (0, 12, and 24 mass % of water in ethanol). d-Fructose, 5-hydroxymethylfurfural, 5-ethoxymethylfurfural, ethyl levulinate, and several other intermediate species are quantified as major species fractions at 45-85% of the initial d-fructose mass. To inform the mechanistic discussion, mass-conserved chemically authentic kinetic models and empirical rate constants are derived, each assuming a first-order relationship to the hydrogen cation concentration. The optimal synthesized fractions of ethyl levulinate and 5-ethoxymethylfurfural considered as fuel components achieve a mass yield of 63% with respect to the fructose mass and a volumetric energy valorization (ΔHcombustion, kcal/mL) of 215% with respect to the ethanol consumed, indicating the viability of the synthesis.
Acid catalysis plays an important role in biomass conversion processes for producing chemicals and fuels. We report a relatively simple procedure for synthesizing versatile, strong acid catalysts based on carbon and carbon–silica composites with sulfonic acid groups. The process involves chemical activation of a sulfonic acid organic precursor at low temperature. The synthesis conditions can be modified to tune the surface composition, texture, and the acid properties of the materials towards superior catalytic performances. Molecular level insights into the nature and strength of the acid sites were gained by combining high resolution XPS and 1H-decoupled 31P MAS NMR spectroscopy of adsorbed triethylphosphine oxide. These materials are effective acid catalysts for the conversion of different biomass-derived chemicals to useful bio products such as furanic ethers and levulinate esters.
A series of acid base bifunctional hybrid nanospheres prepared from the self-assembly of basic amino acids and phosphotungstic acid (HPA) with different molar ratios were employed as efficient and recyclable catalysts for synthesis of liquid biofuel 5-ethoxymethylfurfural (EMF) from various carbohydrates. A high EMF yield of 76.6%, 58.5%, 42.4%, and 36.5% could be achieved, when fructose, inulin, sorbose, and sucrose were used as starting materials, respectively. Although, the acid base bifunctional nanocatalysts were inert for synthesis of EMF from glucose based carbohydrates, ethyl glucopyranoside in good yields could be obtained from glucose in ethanol. Moreover, the nanocatalyst functionalized with acid and basic sites was able to be reused several times with no significant loss in catalytic activity.
Using a continuous flow reactor, the dehydration of D-fructose and other carbohydrates to 5-(chloromethyl)furfural (1) is achieved in reaction times as short as 60 s. The biphasic flow process allows for high-yielding multigram scale production of CMF (1) which is obtained with excellent purity after a simple extractive work-up. Efficient conversion of D-fructose into 5-(hydroxymethyl)furfural (2) and levulinic acid (6) is also demonstrated using flow reactor techniques.
Furan derivatives obtained from renewable biomass resources have the potential to serve as substitutes for the petroleum-based building blocks that are currently used in the production of plastics and fine chemicals. We developed a process for the selective dehydration of fructose to 5-hydroxymethylfurfural (HMF) that operates at high fructose concentrations (10 to 50 weight %), achieves high yields (80% HMF selectivity at 90% fructose conversion), and delivers HMF in a separation-friendly solvent. In a two-phase reactor system, fructose is dehydrated in the aqueous phase with the use of an acid catalyst (hydrochloric acid or an acidic ion-exchange resin) with dimethylsulfoxide and/or poly(1-vinyl-2-pyrrolidinone) added to suppress undesired side reactions. The HMF product is continuously extracted into an organic phase (methylisobutylketone) modified with 2-butanol to enhance partitioning from the reactive aqueous solution.
The direct conversion of glucose to 5-ethoxymethylfurfural (EMF) is a promising biomass transformation due to the potential application of the product as a biofuel. Here, the conversion of glucose to EMF was examined over several solid acid catalysts in ethanol between 96 and 125 °C. Among the catalysts employed, dealuminated beta zeolites [DeAl-H-beta-12.5 (700)] gave a moderate yield of EMF (37%) in a single step catalytic process. A combined catalytic system consisting of H-form zeolite and Amberlyst-15 was found to be more efficient for the transformation of glucose to EMF (46%) via a one-pot, two-step reaction protocol. Alternative biomass-based mono-, di- and polysaccharides also gave moderate to good yields of EMF with the catalytic systems, including fructose which yielded 67% of EMF and 4% of ethyl levulinate (ELevu) along with 10% 5-hydroxymethyl furfural (HMF) in the combined reaction protocol. A significant amount of ELevu (1–16%), a rehydrated product of EMF and a promising fuel additive, was observed in this study. Recyclability studies suggested that it was possible to reuse the DeAl-H-beta-12.5 (700) catalyst in consecutive reactions without significant changes in product yields due to its easy recovery and thermal stability during regeneration.
In this study, we have developed an effective method for the conversion of carbohydrates into liquid biofuels 5-ethoxymethylfurfural (EMF) over a magnetic solid acid catalyst (Fe3O4@CSO3H). The as-prepared magnetic Fe3O4@CSO3H catalyst showed high catalytic activity toward the synthesis of EMF from carbohydrates. The etherification of 5-hydroxymethylfurfural (HMF) with ethanol over Fe3O4@CSO3H catalyst produced EMF with a high yield of 88.4%. The Fe3O4@CSO3H catalyst also showed high activity toward the one-pot conversion of fructose based carbohydrates into EMF. EMF was obtained in a yield of 67.8% from fructose, and that was 58.4% from inulin. The Fe3O4@CSO3H catalyst could be easily collected by an external magnet and reused for several times without the significant loss of its catalytic activity.
The etherification of 5-hydroxymethyl-2-furfural (HMF) over ZrO2 and sulfated ZrO2-SBA-15 was chosen as a case study to analyze (i) the quantitative relationship between the concentration of Lewis and Brønsted acid sites and the catalytic behavior in the above reaction, which is also of industrial relevance for the production of biodiesel additives, and (ii) how the location of zirconia nanoparticles inside or outside the mesoporous channels of SBA-15 could significantly influence the specific reactivity in this reaction, both before and after sulfation. Depending on the loading of zirconia (about 10 or 35 wt%), the characterization data by different techniques (TEM, XRD, BET, Dr-UV–vis, and XPS) agree in indicating that zirconia is located predominantly outside the mesoporous channels as small zirconia nanoparticles for the lower loading, and predominantly inside the mesoporous channels for the higher loading. The concentration of medium–strong Lewis and Brønsted acid sites were determined by pyridine chemisorption monitored by IR spectroscopy. While the concentration of Brønsted acid sites (formed after sulfation) is linearly dependent on the amount of zirconia in SBA-15, a marked deviation is observed for Lewis acid sites. The same conclusion was derived from analysis of the dependence of the catalytic activity in Lewis- or Brønsted-acid-site-promoted reactions. The analysis of these results indicated that the characteristics of the zirconia nanoparticles deposited outside or inside the mesoporous silica channels differ in terms of acid features and in turn of catalytic reactivity.
Abstract Sulfonic mesoporous silicas have demonstrated an outstanding catalytic performance in the esterification of levulinic acid with different alcohols to produce alkyl levulinates, a family of chemicals considered to be excellent oxygenated fuel extenders for gasoline, diesel and biodiesel. Catalyst screening indicated that propylsulfonic acid-modified SBA-15 material was the most active one, among tested materials, due to a combination of moderately strong sulfonic acid sites with relative high surface hydrophobicity. Under optimized reaction conditions (T = 117 °C, ethanol/levulinic acid molar ratio = 4.86/1 and catalyst/levulinic acid = 7 wt%) almost 100% of levulinic acid conversion was achieved after 2 h of reaction, being negligible the presence of levulinic acid by-products or ethers coming from intermolecular dehydration of alcohols. The catalyst has been reused, without any regeneration treatment, up to three times keeping almost the high initial activity. Interestingly, a close catalytic performance to that achieved using ethanol has been obtained with bulkier alcohols.
Cellulose is the most widely distributed source of biomass, and its efficient conversion to a variety of chemicals is important for a sustainable future. In this work, sulfur dioxide (SO2) dissolved in hot water has been demonstrated to be an efficient catalyst for the selective conversion of cellulose to chemicals such as glucose and levulinic acid. The selectivity of products can be tuned by the SO2 concentration, temperature, and reaction time. SO2 acts both as a supply of H+ ions through ionization of H2SO3 when dissolved in water and as a Lewis acid catalyst that breaks the hydrogen bonds in cellulose. Importantly, SO2 in the reaction mixture can be recovered completely by stream stripping, thus avoiding the formation of acidic wastewater. This work provides a new, efficient, and environmentally benign way to convert cellulose to chemicals.
Sulfonic acid-functionalized heterogeneous catalysts have been evaluated in the catalytic dehydration of C-6 monosaccharides into 5-hydroxymethylfurfural (HMF) using dimethyl sulfoxide (DMSO) as solvent. Sulfonic commercial resin Amberlyst-70 was the most active catalyst, which was ascribed to its higher concentration of sulfonic acid sites as compared with the other catalysts, and it gave 93 mol% yield of HMF from fructose in 1 h. With glucose as the starting material, which is a much more difficult reaction, the reaction conditions (time, temperature, and catalyst loading) were optimized for Amberlyst-70 by a response surface methodology, which gave a maximum HMF yield of 33 mol% at 147 C with 23 wt% catalyst loading based on glucose and 24 h reaction time. DMSO promotes the dehydration of glucose into anhydroglucose, which acts as a reservoir of the substrate to facilitate the production of HMF by reducing side reactions. Catalyst reuse without a regeneration treatment showed a gradual but not very significant decay in catalytic activity. (c) 2014, Dalian Institute of Chemical Physics, Chinese Academy of Sciences.Published by Elsevier B.V. All rights reserved.
Graphical abstract
Roadmap for conversion of sugars to platform chemicals.Figure optionsView in workspace
Highlights
► Fractionation of lignocellulosic biomass increases process flexibility. ► Integrated processing of C5 and C6 sugars advances biorefinery development. ► Management of mineral acids used in pretreatment steps is a significant challenge. ► Biphasic reactors allow for recovery and recycle of mineral acids during lignocellulose conversion. ► Biphasic reactors increase process yields for conversion of lignocellulose to platform chemicals.
5-Hydroxymethylfurfural (HMF) is an important intermediate chemical for producing valuable chemicals from biomass and can be synthesized with high yield from the dehydration of fructose in dimethyl sulfoxide (DMSO). Here, we investigate the room temperature separation of HMF from DMSO for a cost effective recovery of the product from the reaction mixture that contains unreacted fructose. BP2000, Norit1240, BP1300, BP880 and XC72 were tested as sorbents. BP2000 and Norit1240 exhibit selectivity and capacity for HMF. Depending on relative concentrations, HMF/fructose separation factors up to 45 for BP2000 and 13 for Norit1240 were obtained. Under certain conditions, by increasing the concentration of fructose in the solution, HMF adsorption increased significantly.
5-Alkoxymethylfurfural ethers are synthesized directly from fructose using ionic liquids (imidazolium propanesulfonic acids) and alcohols in a novel biphasic system.
A low energy intensive process for the production of diesel fuel has been delineated from both 5-(hydroxymethyl)furfural (HMF) and its sugar precursor D-(–)-fructose. Alcoholic solutions of the above produced a mixture of potential bio-diesel candidates namely, 5-(alkoxymethyl)furfural, 5-(alkoxymethyl)furfural dialkylacetal, and alkyl levulinate, in the presence of solid acid catalysts. Sulfonic acid functionalized resins, Amberlyst-15 and Dowex DR2030 showed exceptional reactivity and selectivity for these reactions. Production of another potential diesel candidate 2,5-bis(alkoxymethyl)furan has been optimized through both sequential reduction/etherification and one-pot reductive etherification processes. During the metal catalyzed hydrogenation of HMF, platinum showed an exclusive selectivity for the reduction of the carbonyl functionality of HMF. Both Pt and Pt/Sn supported on Al2O3 catalysts have been optimized for the production of 2,5-bis(alkoxymethyl)furan from HMF. The reaction mechanisms of etherification and reductive etherification have been discussed in detail on the basis of intermediates observed during these processes.
SBA-15 mesoporous silica has been functionalized with arenesulfonic acid groups by means of a one-step simple synthesis approach involving co-condensation of tetraethoxysilane (TEOS) and 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane (CSPTMS) in the presence of a poly(alkylene oxide) block copolymer (Pluronic 123) under acid silica-based catalysis. The resultant materials show hexagonal mesoscopic order and pores sizes up to 60 Å, with acid exchange capacities of ca. 1.3 mequiv. H+ per g SiO2 and surface areas up to 600 m2 g−1. The sulfonic groups anchored to the silica surface of the pore walls are thermally stable to temperatures up to 380 °C and resistant to leaching in organic and aqueous solutions under mild conditions. 31P MAS NMR measurements of chemically adsorbed triethylphosphine oxide and the catalytic properties confirm the presence of Brönsted acid centers in these mesoporous materials containing arenesulfonic acid groups that are stronger than those found in propanesulfonic-modified SBA-15 and Al-MCM-41.
Furan derivatives, such as 5-hydroxymethylfurfural (HMF) and furfural, obtained from renewable biomass-derived carbohydrates have potential to be sustainable substitutes for petroleum-based building blocks used in production of fine chemicals and plastics. We have studied the production of HMF and furfural by dehydration of fructose, glucose and xylose using a biphasic reactor system, comprised of reactive aqueous phase modified with DMSO, combined with an organic extracting phase consisting of a 7 : 3 (w/w) MIBK–2-butanol mixture or dichloromethane (DCM). Experiments with the MIBK–2-butanol mixture were conducted at a temperature of 443 K using mineral acid catalysts (HCl, H2SO4 and H3PO4) at a pH from 1.0 to 2.0, whereas experiments with DCM as the extracting solvent were conducted at 413 K and did not require the use of an acid catalyst. The modifiable nature of the biphasic system allowed us to identify preferred DMSO and pH levels for each sugar to maximize the HMF selectivity at high sugar conversions, leading to selectivities of 89%, 91%, and 53% for dehydration of fructose, xylose, and glucose, respectively. Using these reaction conditions for each monosaccharide unit, we can process the corresponding polysaccharides, such as sucrose (a disaccharide of glucose and fructose), inulin (a polyfructan), starch (a polyglucan), cellobiose (a glucose dimer) and xylan (a xylose polysaccharide), with equally good selectivities at high conversions. In addition, we show that the biphasic reactor system can process high feed concentrations (10 to 30 wt%) along with excellent recycling ability. By processing these highly functionalized polysaccharides, that are inexpensive and abundantly available, we eliminate the need to obtain simple carbohydrate molecules by acid hydrolysis as a separate processing step.
Recently, a new processing technique was developed that converts the carbohydrates found in plant biomass into ethyl levulinate, which has properties making it a possible diesel fuel oxygenate additive. Additionally, the new processing technique applied to oil-containing seeds can create a biodiesel fuel at high yields, while possibly enhancing the cold flow properties that commonly plague biodiesel fuels. The first part of this two-part study focused on ethyl levulinate as a possible diesel fuel oxygenate additive, by investigating the volatility of petroleum diesel/ethyl levulinate mixtures. Volatility was measured with the advanced distillation curve (ADC) method for mixtures containing 1, 2.5, 5, 10, and 20% ethyl levulinate (v/v) and compared with unblended petroleum diesel fuel. In addition, the concentration of ethyl levulinate was tracked during the distillation for each mixture by use of the composition explicit data channel. The second part of this study investigated fatty acid−levulinate ester biodiesel fuel blends as viable petroleum diesel fuel extenders/replacements. This was done by measuring their volatilities and comparing them to a commercially available biodiesel fuel, and also to a petroleum diesel fuel. In addition, distillate fractions were withdrawn to measure the changing composition and energy content during the distillation of the fatty acid−levulinate ester biodiesel blends and commercial biodiesel fuel.
Expected increasing biodiesel production during the next few years will lead to an overproduction of glycerol, which is the main byproduct. The use of glycerol-based additives to improve petrol fuel properties is one of the possibilities currently being explored to utilize this renewable feedstock. In this context, sulfonic acid functionalized mesostructured materials have demonstrated an excellent catalytic behavior in the esterification of glycerol with acetic acid to yield acetylated derivates. Diacetylglycerol (DAG) and triacetylglycerol (TAG, also called triacetin) have been shown to be valuable petrol fuel additives leading to either enhanced cold and viscosity properties when blended with diesel fuel or antiknocking properties when added to gasoline. The activities and selectivities achieved using sulfonic acid functionalized mesostructured materials as catalysts are comparable or even superior to those displayed by conventional acid catalysts, providing values up to 90% of glycerol conversion and over 80% of combined selectivity toward DAG and TAG after 4 h of reaction. The acid strength of the sulfonic acid site has also been found to be an important factor affecting the catalytic performance of these materials. Moreover, these sulfonated mesostructured materials have been reused in repeated catalytic runs after a mild solvent-washing regeneration step yielding similar catalytic performance to that of the fresh catalyst.
Mesoporous silica nanoparticles functionalized with both sulfonic acid (HSO(3)) and ionic liquid (ILs) were synthesized and applied as effective and recyclable catalysts for generating 5-hydroxymethylfurfural (HMF) from fructose. For the first time a high HMF yield of 72.5% was achieved in DMSO systems under mild conditions (90 °C and 3 h). We further studied the kinetics of the fructose-to-HMF conversion and compared the rate constants, reaction orders, and activation energies for the systems with and without bi-functional MSN catalysts.
Procedures for the dehydration of fructose in non-aqueous solvents using Amberlyst 15 strong acid resins and amine salts as catalysts have been developed to give hydroxymethylfurfural (HMF), hydroxymethylfurfural ethers and laevulinate esters with high carbon recoveries. These procedures allow of easy ‘scale-up’ and recovery of catalyst and solvent.
5-Hydroxymethyl-2-furaldehyde (HMF, 1) was produced in 92% yield when d-fructose was dehydrated using dimethylsulphoxide (DMSO) at 150°C for 2 h. The optimum conversion occurred at a d-Fructose: DMSO molar ratioof 8.0. In addition to HMF, small quantities ({precedes above almost equal to} 1%) of oxobis (5-methyl-2-furaldehyde), 4, were also obtained from the reaction. The amount of 4 was substantially increased ({precedes above almost equal to} 30%) when the reaction was carried out in toluene as the solvent with borontrifluoride etherate as the catalyst.
A simple procedure has been developed for the syntheses of functionalized mesoporous materials with sulfonic groups involving the co-condensation of tetraethoxysilane and mercaptopropyltrimethoxysilane in the presence of block copolymers and hydrogen peroxide under acidic conditions. The modified SBA-15 materials show hexagonal mesoscopic order and pore sizes up to 60 Å, with acid exchange capacities ranging from 1 to 2 mequiv of H + /g of SiO 2 , surface areas up to 800 m 2 /g, and excellent thermal and hydrothermal stabilities. The formation of the sulfonic groups during co-condensation of the silica species coincides with enhanced mesoscopic ordering and changes in the adsorption properties of the final materials. 31 P MAS NMR measurements of chemically adsorbed triethylphosphine oxide confirm the presence of Brönsted acid centers that are stronger that those found in Al-MCM-41. Finally, this procedure has been generalized to prepare functionalized mesoporous solids containing sulfonic groups and other organic moieties.
The etherification of 5-hydroxymethyl-2-furfural (HMF) with ethanol is studied over a series of mesoporous silica catalysts (Al-MCM-41 materials with different Si/Al ratio, and zirconia or sulfated zirconia supported over SBA-15) and compared with the behavior of H(2)SO(4) and Amberlyst (R) 15. The observed reaction products were 5-(ethoxymethyl)furan-2-carbaldehyde (EMF), 1,1-dietoxy ethane (DE) and ethyl 4-oxopentanoate (EOP). The selectivity to EMF and EOP is closely related to the presence of Lewis and/or Bronsted acidity on the catalyst, while the formation of DE is probably related to defect sites. The latter, being less reactive, catalyze the side reaction to DE only when strong Lewis and/or Bronsted acid sites are absent. Catalysts with only a strong Bronsted acidity react selectively to form EOP. When strong Lewis acid sites are present in the catalyst, e.g. by introducing ZrO(2) in SBA-15 or when extra-framework isolated AI(3+) sites are present in the mesoporous channels, a high selectivity to EMF was observed. The results indicate that EMF, DE or EOP can be obtained selectively by direct reaction of HMF with bioethanol by tuning the acidity of the catalyst. EMF is a value biodiesel component, but the results also evidence the possibility to obtain selectively EOP in a one-step reaction, opening interesting perspectives to produce valeric biofuels by subsequent selective hydrogenation.
Different lipidic wastes and low-grade oils and fats have been characterized and evaluated as feedstocks for the acid-catalyzed production of FAME. The characterization of these materials has revealed significant contents of free fatty acids, Na, K, Ca, Mg, P, unsaponifiable matter and humidity. Arenesulfonic acid-functionalized SBA-15 silica catalyst has provided yields to FAME close to 80% in the simultaneous esterification-transesterification of the different feedstocks, regardless of their nature and properties, using methanol under the following reaction conditions: 160 °C, 2 h, methanol to oil molar ratio of 30, 8 wt.% catalyst loading, and 2000 rpm stirring rate. Nevertheless, reutilization of the catalyst is compromised by high levels of impurities, especially because of deactivation by strong interaction of unsaponifiable matter with the catalytic sites. The conditioning of these materials by aqueous washing in the presence of cationic-exchange resin Amberlyst-15, followed by a drying step, resulted in a lower deactivation of the catalyst.
Local differences in surface hydrophilicities/hydrophobicities of propyl- and arene-sulfonic-acid modified mesoporous silica and organosilica catalysts have been compared and correlated with their bulk catalytic properties for aqueous-sensitive organic reactions. Syntheses of propyl- and arene-SO3H-modified mesoporous silicas and organosilicas yield materials with different hydrophilicities, especially when ethylsiloxane moieties are incorporated into the silica frameworks. Solid-state two-dimensional (2D) 13C{1H} and 29Si{1H} heteronuclear correlation (HETCOR) NMR spectra prove that the incorporation of hydrophobic ethylsiloxane groups into functionalized mesoporous silica frameworks result in reduced interactions of adsorbed water with the silica framework in general and, importantly, in the immediate vicinities of the SO3H active sites. The hydrophilic/hydrophobic character of the surface, as well as the active site properties depend on the functional species attached. Propyl-sulfonic acid moieties are less acidic but more hydrophobic than arene-SO3H species, leading to superior overall activities for water-mediated acid-catalyzed organic reactions. The etherification of vanillyl alcohol (4-hydroxy-3-methoxybenzylalcohol) with 1-hexanol to yield 4-hydroxy-3-methoxybenzyl-1-hexyl ether is shown to proceed significantly more effectively on SO3H-modified mesoporous organosilicas, compared to wholly siliceous mesoporous supports. The correlation of macroscopic adsorption and reaction results with 2D NMR measurements allows the hydrophilic/hydrophobic surface properties of the mesoporous support to be optimized with respect to water-retention capacities and activities for water-sensitive organic reactions.
Sulfonic-acid functionalized mesostructured silicas have demonstrated an excellent catalytic behavior in the etherification of glycerol with isobutylene to yield tert-butylated derivates. Di-tert-butylglycerols (DTBG) and tri-tert-butylglycerol (TTBG) have shown to be valuable fuel additives leading to decreases in the emission of particulate matter, hydrocarbons, carbon monoxide and unregulated aldehydes. Likewise, said ethers can also act as cold flow improvers for use in biodiesel, reducing also its viscosity. The activities and selectivities achieved over sulfonic acid-functionalized mesostructured silicas are comparable or even superior to those displayed by widely-used macroporous commercial acid resins. Under optimized reaction conditions, these mesostructured catalysts yield a complete glycerol conversion with a combined selectivity towards DTBG and TTBG up to ca. 90%. Furthermore, no formation of undesirable isobutylene oligomers is observed. The acid strength of the sulfonic acid sites has also been found to be an important factor affecting the catalytic performance of these materials.
CMF from biomass ten times faster: Sugars, cellulose, and corn stover are converted into 5-(chloromethyl)furfural (CMF) in only 3 h by digestion with hydrochloric acid in a closed, biphasic reactor at 80–100 °C in >80 % isolated yield. Under the same conditions, chitin gives a mixture of CMF and levulinic acid in a combined yield of 74 %.
The anomeric composition of d-fructose in dimethyl sulfoxide changes when the solution is heated from room temperature to 150 degrees C, with a small increase in the alpha-furanose form at the expense of the beta-pyranose tautomer. Additionally, a small amount of alpha-pyranose form was also observed at 150 degrees C. A mechanism is proposed for the dehydration of D-fructose to 5-hydroxymethylfurfural in DMSO at 150 degrees C, where the solvent acts as the catalyst. A key intermediate in the reaction was identified as (4R,5R)-4-hydroxy-5-hydroxymethyl-4,5-dihydrofuran-2-carbaldehyde by using (1)H and (13)C NMR spectra of the sample during the reaction.
Furane für den Motor: Cellulose lässt sich in zuvor unerreichten Ausbeuten in Furanbiokraftstoffe umwandeln. Dabei kommt ein einfaches, billiges Verfahren mit zeitgleicher Hydrolyse, Dehydrierung und Chlorsubstitution in Kombination mit fortlaufender Extraktion in eine organische Phase zum Einsatz (siehe Schema). Furanether, wie sie aus den gezeigten Produkten erhalten werden können, sind bekannte Dieselzusatzstoffe.
Increasing awareness of the environmental costs of traditional acid-catalyzed chemical processes has created an opportunity for new solid acid catalysts. This review discusses how this opportunity is being addressed through the synthesis and application of these novel acid catalysts based on sulfonic-modified mesostructured materials. Topics discussed include the synthesis of organosulfonic-functionalized mesostructure materials, propylsulfonic-modified mesostructured materials, hydrophobicity control of pore surface in organosulfonic-modified mesostructured materials, tuning the acid strength of anchored sulfonic-acid sites and organosulfonic-functionalized periodic mesoporous organosilica.
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