A heterogeneous catalyst was prepared by immobilizing Zirconyl Schiff base complex on the modified MCM-41 and used in the conversion of fructose to HMF. A higher HMF yield was obtained when fructose as raw material under optimal reaction conditions. 相似文献
A series of mesoporous Nb and Nb‐W oxides were employed as highly active solid acid catalysts for the conversion of glucose to 5‐hydroxymethylfurfural (HMF ). The results of solid state 31P MAS NMR spectroscopy with adsorbed trimethylphosphine as probe molecule show that the addition of W in niobium oxide increases the number of Brønsted acid sites and decreases the number of Lewis acid sites. The catalytic performance for Nb‐W oxides varied with the ratio of Brønsted to Lewis acid sites and high glucose conversion was observed over Nb5W5 and Nb7W3 oxides with high ratios of Brønsted to Lewis acid sites. All Nb‐W oxides show a relatively high selectivity of HMF , whereas no HMF forms over sulfuric acid due to its pure Brønsted acidity. The results indicate fast isomerization of glucose to fructose over Lewis acid sites followed by dehydration of fructose to HMF over Brønsted acid sites. Moreover, comparing to the reaction occurred in aqueous media, the 2‐butanol/H2O system enhances the HMF selectivity and stabilizes the activity of the catalysts which gives the highest HMF selectivity of 52% over Nb7W3 oxide. The 2‐butanol/H2O catalytic system can also be employed in conversion of sucrose, achieving HMF selectivity of 46% over Nb5W5 oxide. 相似文献
A novel, magnetically recoverable carbonaceous solid acid Fe3O4@C-SO3H catalyst for the conversion of carbohydrates to 5-ethoxymethylfurfural (EMF) was developed. The effect of the DMSO fraction in the ethanol-DMSO binary solvent on the distribution of the reaction products was investigated. The catalyst showed an excellent activity in the synthesis of EMF from fructose and 5-hydroxymethylfurfural (HMF). 5- Ethoxymethylfurfural was also obtained with a high yield of 64.2% in an ethanol–DMSO solvent system via one-step conversion of fructose. After reaction, the catalyst could be recovered by exposure of the reaction mixture to external magnetic field and reused several times without a loss of catalytic activity. 相似文献
The aim of this work is to study the production of hydroxymethylfurfural (HMF) from fructose using heterogenous catalysts based on KIT-5. For this propose, Al-KIT-5 and KIT-5-SO3H as the Lewis and Bronsted catalysts were prepared and were characterized using different techniques such as FT-IR, SEM, EDS, TEM, BET, TGA and elemental analysis. With the use of Al-KIT-5 as the catalyst, the appropriate reaction temperature and time were 135 °C and 60 min, respectively. Moreover, with the use of KIT-5-SO3H as the catalyst, the proper reaction conditions were found to be 125 °C and 45 min, respectively. In addition, the corresponding amounts of catalyst weight were 40 and 50 mg for KIT-5-SO3H and Al-KIT-5, respectively. Under these conditions, the conversion of fructose was 93.9 and 88.3%, respectively. These results indicated that, due to its Bronsted acid nature, the KIT-5-SO3H catalyst showed better results when 40 mg catalyst was used at 125 °C for 45 min in DMSO as the solvent. Both catalysts could be recycled and reused several times. 相似文献
Direct conversion of fructose-based carbohydrates to 5-ethoxymethylfurfural (EMF) catalyzed by Lewis acid in ethanol was investigated. It was found that BF3·(Et)2O was favorable for 5-hydroxymethylfurfural (HMF) etherification to EMF. BF3·(Et)2O combination with AlCl3·6H2O with the molar ratio of 1 was an effective catalyst system for synthesis of EMF from fructose-based carbohydrates. 55.0%, 45.4% and 23.9% of EMF yields were obtained from fructose, inulin and sucrose under optimized conditions, respectively. 相似文献
A series of metal‐Al2O3 catalysts were prepared simply by the conventional impregnation with Al2O3 and metal chlorides, which were applied to the dehydration of fructose to 5‐hydroxymethylfurfural (HMF). An agreeable HMF yield of 93.1% was achieved from fructose at mild conditions (100°C and 40 min) when employing Cr(III)‐Al2O3 as catalyst in 1‐butyl‐3‐methylimidazolium chloride ([Bmim]Cl). The Cr(III)‐Al2O3 catalyst was characterized via XRD, DRS and Raman spectra and the results clarified the interaction between the Cr(III) and the alumina support. Meanwhile, the reaction solvents ([Bmim]Cl) collected after 1st reaction run and 5th reaction run were analyzed by ICP‐OES and LC‐ITMS and the results confirmed that no Cr(III) ion was dropped off from the alumina support during the fructose dehydration. Notably, Cr(III)‐Al2O3 catalyst had an excellent catalytic performance for glucose and sucrose and the HMF yields were reached to 73.7% and 84.1% at 120°C for 60 min, respectively. Furthermore, the system of Cr(III)‐Al2O3 and [Bmim]Cl exhibited a constant stability and activity at 100°C for 40 min and a favorable HMF yield was maintained after ten recycles. 相似文献
Due to the increasing concerns about the availability and accessibility of fossil fuel reserves, and the subsequent effect of using them on climate change, production of green energy has recently become a hot area of interest in the research field. As a renewable energy source, biomass conversion to biofuels has shown a great potential towards green fuel production; particularly fructose conversion to 5-hydroxymethylfurfural (5HMF) as a building block material and source of green fuels and other high value chemicals.Herein, we investigate fructose dehydration to 5-hydroxymethylfurfural (5HMF) as a green fuel precursor, using a green self-catalysed environmentally friendly Deep Eutectic Solvent (DES), composed of inexpensive N,N-diethylethanolammonium chloride as organic salt and p-toluenesulfonic acid monohydrate (p-TSA) as a hydrogen bond donor (HBD) and novel medium for the fructose dehydration reaction.The advantage of using this DES is its ability to act as a solvent and catalyst simultaneously. It has shown to actively catalyse the dehydration reaction of fructose under moderate reaction conditions with a high 5HMF yield of 84.8% at a reaction temperature of 80 °C, reaction time of 1 h, DES mixing ratio of 1:0.5 salt to p-TSA (w/w), and initial fructose ratio of 5. 相似文献
Sulfonated carbon dots (SCDs) were synthesized from plant leaves via continuously hydrothermal treatment by hydrogen peroxide and sulfuric acid, used as catalyst for converting fructose to 5-hydroxymethylfurfural (HMF). Owing to nanosize effect and moderate acidic intensity, SCDs could thoroughly distribute in the solvent with an improved interfacial compatibility and selectively convert fructose to HMF. Under the optimal condition, the yield of HMF was 92.6% along with a fructose conversion of 100%, benefiting from a low activation energy of 52.9 kJ/mol when dimethylsulfoxide was used as solvent. The SCDs catalyst can be recovered, after six recycles, the fructose conversion and HMF yield were remained 66.1% and 56.2% under condition with incompletely conversion of fructose, respectively. This work provides a sustainable route to prepare carbon dots with a superior catalytic performance for converting biomass to important biobased platform chemicals. 相似文献
Selective conversion of fructose to 5-hydroxymethyl-furfural (HMF) involves the participation of high-boiling solvents like dimethyl sulfoxide (DMSO). In order to replace DMSO with low-boiling solvents, it is imperative that we understand the effect of DMSO solvation in protecting (i) HMF from rehydration and humins formation reactions and (ii) fructose from side reactions, other than its dehydration to HMF. In the present work, molecular dynamics simulations of HMF and fructose in water and in water-DMSO mixtures are carried out using the OPLS-AA force field. Radial pair distribution functions, coordination numbers and the hydrogen-bond network between the HMF/fructose molecule and the solvent molecules are analysed. The local 3-dimensional picture of the arrangement of solvent molecules around the solute, which cannot be accessed from pair distribution functions, is also computed. We show preferential coordination of DMSO around HMF and explain how this could provide a shielding effect to the HMF molecule, thus protecting it from further rehydration to levulinic acid and formic acid and from humins formation. In the case of fructose, the presence of DMSO also reduces the number of water molecules in the immediate vicinity of fructose. Though fewer water molecules coordinate around fructose, they are bound strongly to it. Analysis of the local 3-dimensional arrangement of DMSO molecules suggests that it protects the fructose molecule from side reactions that would lead to condensation or reversion products. However, the presence of DMSO molecules does not hamper the water molecules coming into contact with the oxygen atom of the hydroxyl groups of fructose, which is required for a proton transfer from water to fructose, to initiate the dehydration reaction to HMF. 相似文献
Four Fe-containing ionic liquids (ILs) were synthesized by coupling of conventional imidazole ionic liquids [Cxmim]Cl (x = 4, 8, 12, 16) with FeCl3 and were characterized by FT-IR, Raman, ESI–MS and TG. All of the Fe-containing ILs were applied to the conversion of fructose into 5-hydroxymethylfurfural (HMF) in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) subsequently and the result showed that [C16mim]FeCl4 exhibited excellent catalytic performance. Then the different reaction parameters with [C16mim]FeCl4 as catalyst were studied in detail. A 92.8% yield of HMF was obtained with 0.03 g [C16mim]FeCl4 and 0.1 g fructose in 1.0050 g [Bmim]Cl at 80 °C for 40 min in fructose/[Bmim]Cl solution. 相似文献
In this paper, we have described a novel route to produce 5-hydroxymethylfurfural (HMF), a valuable platform molecule obtained from biomass. Metal-exchanged Keggin heteropolyacid salts were used as catalysts, in microwave-assisted reactions carried out in a water-ethyl acetate biphasic system. To avoid the use of homogenous Brønsted acid catalysts, which are corrosive and difficult to be reused, we have exchanged the protons of the Keggin heteropolyacids with transition metal cations. These salts were evaluated in the fructose dehydration, being the Cu3/2PW12O40 the most active and selective catalyst, achieving 81% of HMF yield, after 15 min reaction at 413 K under microwave irradiation. The effects of metal cation, anion or heteropolyanion present in the catalyst were evaluated. The greatest efficiency of the Cu3/2PW12O40 was attributed to its high Lewis acidic strength which allows its coordinates with the water molecules, consequently generating H3O+ ions in the reaction medium. In addition, after assessing reactions of fructose dehydration in the presence of other Copper salts [i.e., CuCl2 or Cu(NO3)2], we conclude the anion plays too a key role. The higher softness of phosphotungstic anion should stabilize protonate intermediates better than chloride or nitrate anions, favouring this way the reaction. Finally, although the catalyst has been soluble, it was easily reused by removing the aqueous phase and adding a new load of the substrate dissolved in ethyl acetate. The runs were successfully repeated without the loss of activity of the catalyst.
Fructose was converted to 5-hydroxymethylfurfural (HMF), an important biomass-derived platform chemical, under mild conditions (100–130 °C) with several organic acids including p-toluene sulfonic (pTSA), oxalic, maleic, malonic and succinic acids as the catalysts. The process kinetics was compared considering fructose dehydration to HMF as the objective reaction and condensation of fructose and HMF to humin and rehydration of HMF as the main side reactions. DMSO was found to be the most effective solvent reaction medium to obtain high fructose conversion and HMF yield. Observed kinetic modeling illustrated that the rehydration and condensation of HMF in DMSO actually could be neglected, especially for the oxalic acid catalyzed system. The determined observed activation energy for fructose conversion to HMF and humin in DMSO medium was 33.75 and 24.94 kJ/mol for pTSA catalyzed system, and 96.51 and 78.39 kJ/mol for oxalic acid-catalyzed system, respectively. HMF yields of 90.2% and 84.1% were obtained for pTSA and oxalic acid catalyzed systems, respectively. 相似文献
Sulfonic acid-functionalized heterogeneous catalysts have been evaluated in the catalytic dehydration of C(,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. 相似文献
The utilization of 5‐(hydroxymethyl)furfural (HMF) for the large‐scale production of essential chemicals has been largely limited by the formation of solid humin as a byproduct, which prevents the operation of stepwise batch‐type and continuous flow‐type processes. The reaction of HMF with 1,3‐propanediol produces an HMF acetal derivative that exhibits excellent thermal stability. Aerobic oxidation of the HMF acetal with a CeO2‐supported Au catalyst and Na2CO3 in water gives a 90–95 % yield of furan 2,5‐dicarboxylic acid, an increasingly important commodity chemical for the biorenewables industry, from concentrated solutions (10–20 wt %) without humin formation. The six‐membered acetal ring suppresses thermal decomposition and self‐polymerization of HMF in concentrated solutions. Kinetic studies supported by DFT calculations identify two crucial steps in the reaction mechanism, that is, the partial hydrolysis of the acetal into 5‐formyl‐2‐furan carboxylic acid involving OH? and Lewis acid sites on CeO2, and subsequent oxidative dehydrogenation of the in situ generated hemiacetal involving Au nanoparticles. These results represent a significant advance over the current state of the art, overcoming an inherent limitation of the oxidation of HMF to an important monomer for biopolymer production. 相似文献
In this study, we have developed a new and green method for the synthesis of 5-hydroxymethylfurfural (HMF) and 5-ethoxymethylfurfural (EMF) from fructose using cellulose sulfuric acid as catalyst. Firstly, HMF was synthesized from fructose, and a high yield of 93.6 % was obtained in DMSO for 45 min in the presence of cellulose sulfuric acid. Cellulose sulfuric acid also showed high catalytic activity for the synthesis of EMF. EMF was obtained in a high yield of 84.4 % by the etherification of HMF under the optimal reaction conditions. More importantly, a high EMF yield of 72.5 % was also obtained from fructose through one-pot reaction strategy, which integrated the dehydration of fructose into HMF and the followed etherification of HMF into EMF. The reaction work-up was very simple and the catalyst could be reused several times without the loss of its catalytic activity. 相似文献