Furan Compounds Research Articles

Investigation of the hydrothermal carbonization process of furan compounds derived from cellulose using molecular dynamics

The conversion of biomass, such as cellulose, into carbonaceous materials by hydrothermal carbonization (HTC) has great potential as an energy source. This study was conducted to investigate the effects of temperature, water, and reactants on product distribution during the HTC process. The carbonization reaction mechanism was determined using the ReaxFF method, and the results showed that high temperature accelerated the HTC charring process. Although the rate of reactant polymerization increased at high temperatures, this also led to an increase in the decomposition of gaseous products. Simulation results showed that water played a dual role as both a solvent and reactant in HTC; this role hindered the formation of certain carbon-containing gases, which in turn facilitated the HTC process. It was also observed that 5-hydroxymethylfurfural (HMF) and furfural did not interact, but furfural was converted at a faster rate. At 2200 K, HMF polymerized within 3000 ps to form an insoluble polymer with considerable molecular weight. Based on the formation of the polymer, it was evident that reactive small molecule compounds continued to participate in polymerization. An aromatization reaction occurs during polymerization, leading to the formation of stable fragments with high aromaticity; therefore, polymerization and aromatization reactions are the two fundamental processes driving carbonation reactions. These processes give rise to the production of insoluble polymers characterized by an amorphous network structure and high aromaticity, and polymers with atomic weights exceeding 1000 can be formed under suitable conditions. The results indicate that it is relatively simple to study the HTC mechanism using molecular dynamics methods.

Production and recovery system for furan compounds from rice straw using an ionic liquid (1-methylimidazolium hydrogen sulfate) and vacuum steam distillation

Furan compounds, including 5-hydroxymethylfurfural and furfural, can be synthesized from biomass and have garnered attention for their potential applications in biofuels and resin precursors. In this study, the synthesis of the furan compounds from rice straw was explored using a combined approach of ionic liquid treatment, specifically 1-methylimidazolium hydrogen sulfate ([MIM]HSO4), and vacuum steam distillation. Through the optimization of various processing parameters, we established that the best conditions for the furan compound production include: a cold trap cooling temperature of – 196 ℃, a system pressure of 10 hPa, a treatment temperature of 180 ℃, a reaction duration of 30 min, a sample loading of 1wt%, and a particle size range of 45–90 µm. Under these conditions, the resultant yield of the furan compounds was quantified at 27.9wt%. Additionally, the recyclability of the utilized ionic liquid was evaluated. Notably, even after four recycling cycles (encompassing a total of five reactions), the yield of the furan compounds remained consistent, underscoring the viability of ionic liquid reuse.

Tandem catalysis of furfural to γ-valerolactone over polyoxometalate-based metal-organic frameworks: Exploring the role of confinement in the catalytic process

Polyoxometalate-based metal-organic frameworks (POMOFs) with bifunctional Lewis-Brønsted acid were designed by confining polyoxometalates (POMs: phosphotungstic acid (PW), phosphomolybdic acid (PMo) or silicotungstic acid (SiW)) within the Zr-MOFs. The confined POMs not only have their own Brønsted acid, but can also regulate the Lewis acid strength of the POMOFs via charge regulation, ultimately allowing the POMOFs to display superior catalytic performance in the tandem catalysis of furfural (FAL) to γ-valerolactone (GVL). Among the three catalysts (POMOF-PW, POMOF-PMo and POMOF-SiW), a complete conversion of FAL was achieved, while POMOF-PW exhibited the highest GVL yield (58.1 %) at 160 °C within 23 h. The leaching experiment and structural characterization of the catalyst before and after recycling confirmed the stability of the catalyst structure. The humin originates from the polymerization of furan ring-containing compounds driven by Brønsted acid. The adsorption configuration of the substrate molecules on the catalyst offers a new explanation for the tandem reaction process, i.e. that perpendicular adsorption performs only the first step of the tandem reaction, while the coexistence of perpendicular and horizontal adsorption permits the entire reaction process. This work gives unique insights into the tandem reaction of FAL and can guide the design of efficient tandem reaction catalysts.

Valorization of humins into furanyl functionalized biochar for selective hydrogenation of five-member rings of furan compounds

Humins, an unavoidable by-product of the acid-catalyzed conversion of carbohydrates, significantly limits the yield of platform molecules and accounts for the majority of carbon loss in the biomass utilization processes. Therefore, the utilization and recovery of humins is highly importance to enhance the atom efficiency of biomass valorization. In this work, using potassium ferrate (K2FeO4) to realize synchronous carbonization and graphitization, humins obtained from the dehydration of fructose is transformed into a novel porous biochar material and further applied to prepare noble metal based hydrogenation catalysts. By tuning the carbonization temperature, we demonstrate biochar calcined at 600 °C has large mass specific surface area while retaining abundant furan groups in the framework. With the high density of furan groups in structure, the Pd/biochar catalysts enhances the preferential adsorption capability of furanyl functional groups, thereby promoting the hydrogenation rate of furan compounds and improving the hydrogenation selectivity of furan rings. The demonstration of this novel application of humins will not only enhance the carbon efficiency of biomass conversion processes but also provide functionalized materials for catalytic applications.

Total hydrogenation of furfural on Pd/COFs under mild conditions

Total hydrogenation of furfural (FAL) is an efficient way to produce the industrially important tetrahydrofurfuryl alcohol (THFOL). However, it is a challenge to obtain highly selective catalysts for this transformation especially under mild reaction conditions. Herein, we report that the β-ketoenamine-linked covalent organic framework (TpBD COF) supported ultrafine Pd nanoparticles exhibit significantly enhanced selectivity for THFOL compared to Pd/C (95% vs. 82 %) at almost full FAL conversion. This heightened selectivity is attributed to the increased electronic density on the Pd surface, resulting from the electron-donating effect of pendant groups in the TpBD COF. Moreover, kinetic investigations reveal that the activity of total FAL hydrogenation on Pd surface is linked to the rate-determining step in its first C = O hydrogenation process. Additionally, Pd/TpBD COF could catalyse various other bio-based furanic compounds to the corresponding furan ring saturated products in high yields. This work provides guidance for the rational design catalysts to improve its tandem hydrogenation efficiency.

Characteristic volatile components analysis of Camelina sativa (L.) Crantz by GC-MS and their antibacterial and antioxidant activities

Camelina sativa (L.) Crantz is an oilseed plant common in Europe and Asia. This study used the gas chromatography–mass spectrometry (GC-MS) to examine the differences in the aroma on the basis of extraction method such as water distillation extraction (CSPW), Solid-phase microextraction (CSPM) and subcritical extraction (CSPS). Antibacterial test was evaluated by the microdilution method against Salmonella typhimurium, Streptococcus pneumoniae, Escherichia coli, Strepococcus pyogenens, Staphylococcus aureus, and antioxidant activity was determined through DPPH free radical, hydroxyl free radical, and superoxide anion radical scavenging capacity activity. The result revealed that three extraction methods were distinct from each other based on their volatile compounds. Sixty-one volatiles of diverse chemical nature were identified and quantified. The volatile components contain thioether, aldehydes, alcohols, ketones, acids, esters, alkene, alkanes, amide, and furan compounds. The volatile components of Camelina sativa (L.) Crantz have good antibacterial and antioxidant activities. Furthermore, this work provides reference methods for detecting novel volatile organic compounds in plants and products.

Determination of impregnation parameters and volatile components in vacuum impregnated apricots

An investigation was conducted to analyse the impact of vacuum impregnation (VI) on aroma profile of intermediate-moisture apricots. cv. Hacihaliloğlu and cv. Kabaaşı apricots were immersed in a variety of solutions, including citric acid and sucrose, as well as plant extracts like rosehip, roselle, and rhubarb. According to the results, solid loss and water gain were observed in all infused samples by VI, while osmotic dehydration occurred in the apricots after immersing in sucrose solution. After all process, a total of 71 volatile compounds were detected in the Hacihaliloglu variety and 66 in the Kabaasi variety. These components are aldehydes, ketones, esters, furan compounds, alcohols, terpenes, isoprenoids, and acids, collected in eight groups. Vacuum impregnation had positive effects on terpenes in both cultivars.

Hydrogen‐Induced Formation of Surface Acid Sites on Pt/Al(PO3)3 Enables Remarkably Efficient Hydrogenolysis of C−O Bonds in Alcohols and Ethers

AbstractThe hydrogenolysis of oxygenates such as alcohols and ethers is central to the biomass valorization and also a valuable transformation in organic synthesis. However, a mild and efficient catalyst system for the hydrogenolysis of a large variety of alcohols and ethers with various functional groups is still underdeveloped. Here, we report an aluminum metaphosphate‐supported Pt nanoparticles (Pt/Al(PO3)3) for the hydrogenolysis of a wide variety of primary, secondary, and tertiary alkyl and benzylic alcohols, and dialkyl, aryl alkyl, and diaryl ethers, including biomass‐derived furanic compounds, under mild conditions (0.1–1 atm of H2, as low as 70 °C). Mechanistic studies suggested that H2 induces formation of the surface Brønsted acid sites via its cleavage by supported Pt nanoparticles. Accordingly, the high efficiency and the wide applicability of the catalyst system are attributed to the activation and cleavage of C−O bonds by the hydrogen‐induced Brønsted acid sites with the assistance of Lewis acidic Al sites on the catalyst surface. The high efficiency of the catalyst implies its potential application in energy‐efficient biomass valorization or fine chemical synthesis.

Hydrogen-Induced Formation of Surface Acid Sites on Pt/Al(PO3)3 Enables Remarkably Efficient Hydrogenolysis of C-O Bonds in Alcohols and Ethers.

The hydrogenolysis of oxygenates such as alcohols and ethers is central to the biomass valorization and also a valuable transformation in organic synthesis. However, a mild and efficient catalyst system for the hydrogenolysis of a large variety of alcohols and ethers with various functional groups is still underdeveloped. Here, we report an aluminum metaphosphate-supported Pt nanoparticles (Pt/Al(PO3)3) for the hydrogenolysis of a wide variety of primary, secondary, and tertiary alkyl and benzylic alcohols, and dialkyl, aryl alkyl, and diaryl ethers, including biomass-derived furanic compounds, under mild conditions (0.1-1 atm of H2, as low as 70 °C). Mechanistic studies suggested that H2 induces formation of the surface Brønsted acid sites via its cleavage by supported Pt nanoparticles. Accordingly, the high efficiency and the wide applicability of the catalyst system are attributed to the activation and cleavage of C-O bonds by the hydrogen-induced Brønsted acid sites with the assistance of Lewis acidic Al sites on the catalyst surface. The high efficiency of the catalyst implies its potential application in energy-efficient biomass valorization or fine chemical synthesis.

Nitrile Furanics via Copper‐Catalyzed Dehydration of Aldoximes and Knoevenagel Condensation

AbstractIn this work two synthetic approaches to introduce nitrile moieties into bio‐based derived furanic compounds were investigated, i. e., dehydration of aldoximes and Knoevenagel condensation. Both methodologies have been first tested and optimized on furfural and thus exploited on 5‐hydroxymethyl‐2‐furfural (HMF) and 5,5’‐oxy(bismethylene)‐2‐furaldehyde (OBMF). The syntheses of furfural, HMF and OBMF aldoximes were efficiently conducted (also in large scale) under mild reaction conditions and short reaction time. The subsequent dehydration to nitrile furanic compounds was carried out in the presence of catalytic amount of copper acetate monohydrate. Furthermore, Knoevenagel condensations were performed on furfural, HMF and OBMF with different Activated Methylene Group compounds, using for the first‐time dimethyl carbonate as the reaction media. Most of the resulting products were isolated as pure via simple liquid‐liquid extraction in good to excellent yields. Future applications of these compounds might include aldoxime reduction into amine furanics ‐ herein also preliminary investigated ‐ and hydrolysis of the nitrile derivatives in the related carboxylic acid (or ester) furanics. All these products are interesting monomers for the preparation of bio‐based polymers.

Pt/MgxAlOy bifunctional catalysts with various Mg/Al ratios for selective hydrogenation of furfural alcohol to 1,2-pentanediol

The selective production of valuable 1,2-pentanediol (1,2-PeD) by biomass-derived furfural alcohol (FFA) hydrogenation is challenging due to the diverse unsaturated groups and robust C5–O bond. Here, a series of Pt/MgxAlOy catalysts with tunable Mg/Al molar ratio were modified to adjust metal-support interactions and oxygen vacancy in promoting FFA hydrogenation in aqueous phase. Among them, Pt/Mg7AlO exhibited excellent catalytic performance, reaching almost complete conversion of FFA and the highest selectivity of 64.9% to 1,2-PeD. A combination study involving X-ray photoelectron spectroscopy (XPS), in situ CO diffuse reflectance Fourier transform infrared spectroscopy (CO-DRIFTS) and in situ FT-IR, confirms that the electrons-rich Pt0 species contribute to the significantly enhanced FFA hydrogenation via promoting C5–O bond cleavage. In-situ FT-IR experiments give direct evidence that the unique distorted adsorption mode of C4=C5–O groups in FFA induces high selectivity for targeted 1,2-PeD over Pt/Mg7AlO, while the parallel adsorption of furan ring is extremely suppressed. This study emphasizes the significance for optimizing defect sites of MgxAlOy in rationally tuning Pt surface states for selective hydrogenation of biomass-derived furan compounds.

Effect of potassium in copper catalysts on selective C–O bond activation of furfuryl alcohol

Selective C-O bond activation in biomass-derived furanic compounds is essential for biomass upgrading. Hydrogenolysis of furfuryl alcohol (FFA) provides two value-added chemicals 1,5-pentanediol (1,5-PDO) and 1,2-pentanediol (1,2-PDO), the generation of both involve selective C-O bond cleavage of FFA, but the respective catalytic active sites still remain obscure. Here we prepared a series of potassium-modified basic oxide supported Cu catalysts and found the product distribution of 1,2-PDO/1,5-PDO selectivity ratio decreased with the rise of K loadings. Various characterization techniques show that the Cu/MgO mainly consists of Cu nanoparticles, while the 2 K-Cu/MgO is dominant by oxidized Cu species especially Cu+. It is proposed that the selective C-O bond cleavage of the furan ring of FFA to 1,5-PDO over basic oxide supported Cu catalysts is attributed to Cu+ species, while the formation of 1,2-PDO is dependent on Cu nanoparticles. This work sheds light on the selective C-O bond activation in the biomass-derived furanic compounds.

Unravelling caramelization and Maillard reactions in glucose and glucose + leucine model cakes: Formation and degradation kinetics of volatile markers extracted during baking

A large number of volatile compounds are formed during the baking of foods by reactions such as caramelization and Maillard reactions. Elucidating the reaction mechanisms may be useful to predict and control food quality. Ten reaction volatile markers were extracted during baking of solid model cakes implemented with known amounts of precursors (glucose with or without leucine) and then quantified by Thermal desorption–Gas chromatography–Mass spectrometry. The kinetic data showed that the level of air convection in the oven had no significant influence on the reaction rates. In contrast, increasing baking temperatures had a nonlinear accelerating impact on the generation of newly formed volatile compounds with a bell–shaped kinetic curve found for most of the markers at 200 °C. The presence of leucine triggered the activation of the Maillard and Strecker routes with a specific and very rapid formation of 3–Methylbutanal and pyrazines. A dynamic model was developed, combining evaporation flow rate and kinetic formation and consumption of reaction markers. It can be used to describe, for two furanic compounds of different volatilities, the vapor concentrations in the oven from the concentrations measured in the model cakes.

CoCuMgAl-Mixed-Oxide-Based Catalysts with Fine-Tunable Composition for the Hydrogenation of Furan Compounds

Catalysts based on CoCuMgAl mixed oxides were synthesized and studied in the hydrogenations of furfural and 5-hydroxymethylfurfural under different conditions. The changes in the structural properties of the catalysts at different stages of their preparation were studied using a set of physical methods (XRD, SEM, and TEM). It was shown that the fine regulation of the chemical compositions of the mixed oxides (i.e., changes in the Co/Cu ratio) made it possible to vary the structure, morphology, and catalytic properties of the samples. The phase composition of catalysts with Co/Cu = 1 did not change during the catalytic reaction, although the initial catalysts had a less-homogeneous morphology. 5-hydroxymethylfurfural conversion was higher for the samples with Co/Cu = 1. Furfural conversion increased when raising the Co/Cu ratio. The selectivity toward furfuryl alcohol for the catalyst with Co/Cu = 2 under mild conditions of furfural hydrogenation was more than 99%. The results obtained are important for the development of the scientific foundations of the preparation of hydrogenation catalysts with a fine-tunable composition in order to obtain the desired hydrogenation products.

Influence of the type of Sherry wine and the length of time of the seasoning on phenolic and furanic compounds and CIEL*a*b* parameters of Brandies de Jerez

Brandy de Jerez is a unique spirit characterized by its aging in Sherry Casks®. Seasoning softens the casks’ wood and removes part of its extractable compounds, some of which are undesirable from an organoleptic point of view. The seasoning wine contributes with specific compounds that otherwise either would not be present at all in Brandies de Jerez, or they would in lower quantities. The length of time and the type of Sherry wine are two key parameters to be controlled when considering the seasoning process. In this study, a number of Brandies de Jerez have been aged in casks that were previously seasoned for 3, 6, 12, 18 or 60 months using either one out of three different Sherry wine types or a young fortified wine. It has been demonstrated that, according to the seasoning time and the type of wine used, significant variations with regard to phenolic and furanic compounds and CIEL*a*b* parameters would be detected between the brandies aged in the different casks.

Thermophysical properties of the biofuel components: A mini-guide to the critical properties, heat capacities, and thermal conductivities

Experimental data on the critical temperature, critical pressure, heat capacity, and thermal conductivity of the compounds involved in the production of biofuels have been compiled and critically evaluated. The compilation contains the critical temperature and critical pressure of 56 compounds, the heat capacity of 63 compounds, and the thermal conductivity of 35 compounds and covers the period from 1886 to September 2023. The recommended values of the critical temperatures and pressures have been determined. The parameters of correlating polynomials for the temperature dependence of heat capacities and thermal conductivities have been obtained. The compounds under consideration are the components of biofuels or platform chemicals. Some methyl and ethyl esters of saturated and unsaturated acids, furanic compounds, levulinic acid and alkyl levulinates, gamma-valerolactone, alpha-angelica lactone, triglycerides, and several alkyl pentanoates are among the compounds studied.

Estimating the age of power transformers using the concentration of furans in dielectric oil

Transformers have an insulation system based on dielectric oil and paper. Several factors as shortcircuits, high load, or overheating influence the aging of the insulating system. Thus, these materials are decomposed during transformer operation, and its state determines the status of the transformer. The degree of polymerization of dielectric paper is an indicator of its real condition. The concentration of furanic compounds in oil offer an estimation of paper degradation. Moreover, these compounds are easy to measure from oil samples. This paper review equations which relate one or more properties of the insulating system with the life expectancy of the transformer. These equations were used in a fleet of transformers in order to estimate the accuracy of these mathematical models. Results show that these methods achieve the most reliable estimation when the transformers have operated less than 8 years. Nevertheless, when the transformers are older, the estimation of lifetime based on furanic compounds is quite erratic and should be improved.

Effect of ultrasound treatment on porcine myofibrillar protein binding furan flavor compounds at different salt concentrations

The effects of ultrasound (500 W) on the interaction of porcine myofibrillar protein (MP) with furan flavor compounds at different salt concentrations (0.6 %, 1.2 % and 2.4 %) were investigated. With the increase of salt concentration, the particle size of MP decreased, and the surface hydrophobicity and active sulfhydryl content increased due to the unfolding and depolymerization of MP. At the same time, ultrasound promoted the exposure of hydrophobic binding sites and hydrogen bonding sites of MP in different salt concentration systems, thus improving the binding ability of MP with furan compounds by 2 % to 22 %, among which MP had the strongest binding capacity of 2-pentylfuran. In conclusion, ultrasound could effectively promote the unfolding of the secondary structure of MP, which was beneficial to the combination of MP and furan flavor compounds under different salt concentrations.

Mitigation of quorum sensing mediated virulence factors of Pseudomonas aeruginosa: the role of Meldrum's acid activated furan.

The rapid emergence of drug resistant pathogens is a major threat which has warranted the development of alternative strategies to combat infectious diseases. In this work, we have tested the anti-virulent activity of Meldrum's acid activated furan (MAF) and 1,3-dimethyl barbituric acid activated furan (BAF) against Chromobacterium violaceum and Pseudomonas aeruginosa. It was found that MAF significantly reduced the violacein production and biofilm formation of C. violaceum at sub-inhibitory concentrations. The quorum sensing (QS) regulated virulence factors of P. aeruginosa including biofilm formation, motility, pigment production, and elastase activity were also found to be reduced considerably at sub-inhibitory concentrations of MAF. Additionally, MAF downregulated the expression of genes in the QS circuitry of P. aeruginosa, demonstrating the potential of MAF in lowering the pathogenicity of P. aeruginosa. In silico studies demonstrated the potential of MAF to compete with the signaling molecules of C. violaceum and P. aeruginosa for the QS receptor interaction. In vivo studies using Caenorhabditis elegans demonstrated the anti-pathogenicity of MAF by enhancing the survival of P. aeruginosa-infected C. elegans. These results suggest that activated furan compounds could be potential inhibitors of QS-mediated virulence factors in C. violaceum and P. aeruginosa, encouraging their use in combating multidrug-resistant pathogens.

Promoting microbial fermentation in lignocellulosic hydrolysates by removal of inhibitors using MTES and PEI-modified chitosan-chitin nanofiber hybrid aerogel

To further enhance the removal efficiency for furanic and phenolic compounds in lignocellulosic hydrolysates, a new detoxification strategy was proposed, which retained fermentable sugars and promoted the growth and metabolism of subsequent bacteria. The best adsorbent (P/M-CCA) was prepared by hybrid chitosan-chitin nanofiber, graft modification with polyethylenimine, and silanization with methyl triethoxylsilane in order. Taken corn cob hydrolysate as object, the removal rates of HMF and furfural were 85.1 % and 99.0 %, respectively. The removal rates of six out of nine phenolic inhibitors were 100 %, and the other three were more than 65 %. Even better, the retention rates of glucose and xylose were both 100 %. In contrast to no growth in undetoxified hydrolysates, Bacillus coagulans grew normally in detoxified hydrolysates, and lactic acid reached 19.1 g/L after 12 h fermentation. P/M-CCA achieves both removal of multiple inhibitors and retain sugars, which would promote the valorization of highly toxic lignocellulosic hydrolysates.