Search

• First study to compare low blend ratio MF20 and MTHF20 with neat ULG in a DISI engine. • MTHF20 exhibits improved specific fuel consumption over MF20 across all load conditions. • MTHF20 achieves the highest thermal efficiency at most mid-range loads. • Unburned furan emissions from MF20 and MTHF20 accounted for only 3 % of total HC at 280 °CA BTDC. The nearing depletion of fossil fuels and the possible consequences of its emissions on the global climate has prompted a worldwide probe for their alternatives. 2-methylfuran and 2-methyltetrahydrofuran are considered promising alternative fuels for spark ignition engines. In this study, the combustion and emission characteristics of low blending ratio MF20 (2-methylfuran 20 %, gasoline 80 % by volume) and MTHF20 (2-methyltetrahydrofuran 20 %, gasoline 80 % by volume) were first implemented and compared to neat gasoline in a single-cylinder direct injection spark ignition engine. The combustion performance of the test fuels was analyzed across a range of loads from 3.5 to 8.5 bar indicated mean effective pressure and fuel injection timings between 180 and 280 crank angle degrees before top dead center. Meanwhile, the compositions of the hydrocarbon emissions were experimentally investigated using the Fourier Transform Infrared Spectroscopy technique. Results show that MF20 exhibits advanced spark timing flexibility of 8 and 7 crank angle degrees before top dead center compared to the unleaded gasoline and MTHF20 respectively at the peak load. MTHF20 exhibits the highest maximum cylinder pressure at medium load compared to other fuels but drops sharply at peak load accompany with the audible knock. Additionally, MTHF20 exhibits specific fuel consumption advantage over MF20 across the entire load range. The unburned furan of the total hydrocarbon emissions was recorded to be 3 % of total hydrocarbon emissions. The concept of low blending ratio furan-based fuel proposed could provide a solution for the transition period of carbon neutrality. [ABSTRACT FROM AUTHOR]

The Ni/SiO 2 catalysts synthesized by impregnation, urea-assisted impregnation, and deposition–precipitation methods displayed different structure and catalytic performance for 2-methylfuran hydrogenation to 2-methyltetrahydrofuran in vapor phase. [Display omitted] • Development of 2-MF vapor phase hydrogenation instead of liquid phase process. • Development non-noble metal Ni catalyst satisfy the vapor phase process. • The catalyst showed exceptional activity, selectivity and stability. • Reaction pathway and deactivation mechanism have been demonstrated. • The catalyst showed high-value in future industrial application. Biomass-derived 2-methyltetrahydrofuran (2-MTHF) is a significant green solvent and a promising biomass fuel, and it is usually produced from 2-methylfuran (2-MF) hydrogenation in liquid phase. It is highly desirable and challenging to develop vapor-phase hydrogenation with such a catalyst that combines high efficiency, excellent stability, easy scale up and low cost. In the present work, we prepared three Ni/SiO 2 catalysts using impregnation, urea-assisted impregnation, and deposition–precipitation methods (labeled as NS-IM, NS-UIM, and NS-DP), respectively, for the synthesis of 2-MTHF from 2-MF hydrogenation in vapor-phase. The NS-DP catalyst demonstrated the highest activity and the best stability among all catalysts. Under moderate reaction conditions, a 2-MF conversion of 99.9% with a 2-MTHF selectivity of 99% were achieved on the NS-DP catalyst over 140 h, and it showed a potential significant application prospect. N 2 physisorption, ICP, XRD, H 2 -TPR, TG, HRTEM, and in situ XPS characterization revealed that the catalyst prepared by the deposition–precipitation method possessed the smallest Ni grain size and the strongest metal-support interaction, leading to the highest performance. It was demonstrated that reaction pressure affected the conversion of 2-MF while the reaction temperature affected the selectivity of 2-MTHF. In addition, the structures of the spent catalysts were characterized, and mechanism of deactivation have been discussed in this work. [ABSTRACT FROM AUTHOR]

The enzymatic synthesis of sugar-based surfactants is often performed in non-conventional media that do not meet any longer the current environmental acceptability, especially for biodegradability and cytotoxicity. In this work, we propose innovative sustainable routes by replacing the current reference organic solvent, 2-methyl-2-butanol (2M2B) by either 2-methyltetrahydrofuran (MeTHF), an agrosolvent, or 2-methyltetrahydrofuran-3-one (MeTHF-3-one), a food-grade ingredient used as solvent. These two neoteric solvents were thus evaluated as reaction media via a lipase-catalyzed esterification of glucose by lauric acid and revealed a novel matter of interest. The regioselectivity of the reaction was mainly directed toward the primary alcohol of glucose maintaining the end-product obtained in 2M2B: D -glucose-6-O-laurate. The PLS-Surface Response Design evidenced enzymatic performances in ester production of 48% in MeTHF and 79% in MeTHF-3-one. The latter solvent resulted not only in better yields compared to 2M2B, but also in an increased enzymatic stability, allowing better reuse of the catalyst. MeTHF-3-one has been shown to be readily biodegradable according to OECD standards. Herein, this solvent has been substantiated for the first time as a green medium in an efficient, selective and sustainable enzymatic synthesis of sugar esters. [Display omitted] • Enzymatic synthesis of glucose ester in 2-Methyltetrahydrofuran-3-one succeeded. • 2-Methyltetrahydrofuran-3-one was firstly reported as readily biodegradable. • Initial velocity and final glucose ester yield were improved in this solvent. • Novozym 435® exhibited a stability in 2-Methyltetrahydrofuran-3-one allowing reuses. [ABSTRACT FROM AUTHOR]

[Display omitted] • The efficient production of 1,3-pentadiene from 2-MTHF over rare-earth phosphates. • The highest 1,3-pentadiene yield of 97.2 reported to date was obtained. • The ring-opening process of 2-MTHF was studied by in-situ DRIFTS. • A unique reaction pathway for the dehydra-decyclization of 2-MTHF was proposed. • The acid-base coupling catalysis was demonstrated by poisoning experiments. It is critical to increase the reaction selectivity and atom economy, avoid side reactions during the catalytic process, and achieve the desired single-target product. Here, an efficient and novel method of producing 1,3-pentadiene via the acid-base coupling of rare-earth phosphate-catalyzed dehydra-decyclization of 2-methyltetrahydrofuran (2-MTHF) is reported, resulting in a previously unreported 1,3-pentadiene yield of 97.2% at 350 ℃. This method efficiently addresses two significant problems encountered in the dehydra-decyclization of 2-MTHF to generate 1,3-pentadiene research: the occurrence of retro -Prins condensation and the competitive reaction of 1,4-pentadiene. Density-Functional-Theory calculations demonstrated that 2-MTHF was adsorbed on the surface of rare-earth phosphate catalysts in a multi-site parallel mode, resulting in a lower apparent activation energy and ring-opening energy barrier. Space-time investigations and in situ diffuse reflectance infrared Fourier transform spectroscopy provided evidence for direct synthesis of pentadiene on rare-earth phosphate catalysts with Lewis acid-base sites. The acid-base coupling catalysis was demonstrated by poisoning experiments. In-situ self-regeneration of Brønsted acid sites was confirmed by infrared spectroscopy of adsorbed pyridine, facilitating the isomerization of 1,4-pentadiene to 1,3-pentadiene. Therefore, a unique reaction pathway for the dehydra-decyclization of 2-MTHF on the surface of rare-earth phosphates was proposed, and a new rotational isomer was discovered. [ABSTRACT FROM AUTHOR]

[Display omitted] • Alumina-niobia-supported nickel-copper catalysts were synthesized and characterized. • The role of the acidic properties of the catalysts in LA conversion to valuable chemicals was unveiled. • Up to 85.0 % MTHF selectivity was achieved in a solvent-free LA conversion. • A comprehensive reaction pathway of LA conversion was proposed. The catalytic transformation of levulinic acid (LA) represents a pivotal advancement towards establishing a sustainable biorefinery industry. Hence, this study investigated the intricate role of the catalyst acidity, which remains relatively unexplored, in the catalytic transformation of LA. A range of alumina-niobia supported nickel-copper catalysts, with varying alumina (Al) to niobia (Nb) ratios, was synthesized and characterized. The results of characterization techniques revealed that the strength, quantity, and nature of the acidic sites of the catalysts were modified by the variations in the Al to Nb ratios. Further, a correlation between the acidic properties of the catalysts and the result of the reaction runs and poisoning experiments was established. Specifically, Lewis acid sites were responsible for the conversion of LA into angelica lactone (AL), which can be subsequently hydrogenated to gamma-valerolactone (GVL). Conversely, Brønsted acid sites are required for the ring-opening reactions of GVL which led to the formation of 2-methyltetrahydrofuran (MTHF) and valeric acid (VA). Notably, selectivities as high as 85.0% for MTHF and 67.0 % for VA were achieved with Ni-Cu/Al-Nb (6) and Ni-Cu/Nb 2 O 5 , respectively. To the best of our knowledge, this represents the highest MTHF selectivity in solvent-free catalytic conversion of LA. Additionally, based on our findings, we propose a comprehensive reaction pathway employing alumina-niobia-supported nickel-copper catalysts, shedding light on the intricate interplay of acidity in the LA conversion process. This study not only deepens our understanding of LA transformation but also holds great promise for optimizing catalytic processes in pursuit of sustainable and eco-friendly biorefinery technologies. [ABSTRACT FROM AUTHOR]

The laminar burning velocities (LBVs) and cellular instability of 2-methyltetrahydrofuran (2-MTHF) were investigated at the unburned temperature of 423 K and pressures from 1 to 10 atm in a cylindrical constant-volume vessel. The LBVs of 2-MTHF/air flame exhibit a notably dropping with increasing pressure. The cellular instability analysis indicates that the critical flame radius of 2-MTHF/air mixture monotonically increases with increasing pressure and the flame surface suffers more badly cellularity under higher pressures. The critical flame radius exhibits non-monotonic variation versus ϕ and the most unstable flames appear at ϕ ≈ 1.3. It is observed that the measured Markstein length of 2-MTHF/air mixture decreases with increasing ϕ and P u , leading to an earlier formation of wrinkling and cracks with respect to preferential-diffusional instability. Further investigation found that by using a mixture of 14.2% oxygen with 85.8% helium in place of air as bath gas at 10 atm can effectively suppress the cellular instability. Two recently developed models were used to simulate the experimental results and explore the chemical kinetic effects on LBV. Reaction path analysis reveals that the most consumption of 2-MTHF/air at stoichiometric conditions is through the abstraction of H-atom to form radical C 5 H 9 O-5. While the competitiveness of decomposition by C C scission yielding CH 3 and tetrahydrofuran radical is relatively weak. Sensitivity analysis illustrates that small-species reactions show a controlling effect on LBV. The increasing pressure leads to an evident increase in the sensitivity coefficient of the recombination reaction H + O 2 (+ M)=HO 2 (+ M). The reduction of H atom concentration will cause competition to the initiation reaction H + O 2 = O +OH. This could lower the overall oxidation rate and reduce the burning velocity. [ABSTRACT FROM AUTHOR]

• Models (1D, 3D CFD) were prepared for the extraction of levulinic acid. • The models fit the experimental extraction column data with an excellent accuracy. • The models proved to be a very valuable tool for scale-up and design purposes. 1D axial dispersion and 3D CFD models for the extraction of levulinic acid from dilute aqueous solution by applying 2-methyltetrahydrofuran as a solvent are presented. The models are validated by comparison with the measured levulinic acid concentration profile data obtained in a bench-scale Kühni column. The 1D model contains NRTL parameters for the system levulinic acid-water-2MTHF. Correlations for drop size and hold-up for Kühni columns were taken from literature. The values for overall mass transfer coefficient ranged from 1.4E-5 to 2.2E-5 ms−1, and increased as a function of the rotor speed. The fitting of the column performance resulted in a very good prediction of the solute concentration profiles in the extraction column, and the average absolute value of relative error for the 1D model was 23%. CFD model visualized the column performance at the column height of 150.5–160 cm giving valuable information on back mixing, phase velocities, dispersed phase volume fraction, and mass transfer. Dispersed phase volume fraction and mass transfer contours revealed, that the mass transfer rate (app. 0.25 g L−1s−1) is at its highest just below the rotor, and that there are blind spots in the compartments close to the extractor and just above each down comer. Values for the dispersed phase volume fraction are highest in the same area where the mass transfer reaches the highest values. The highest slip velocity values (app. 0.03 m−1) are located in the tip of each compartment partition plates. General correlations, such as hold-up and drop size correlations, can successfully be applied in levulinic acid-water-2MTHF system reported in this work. The 1D axial dispersion model proved to be valuable tool for scale-up purposes, and CFD model, despite the long time needed for each simulation, gave useful information for the design purposes. [ABSTRACT FROM AUTHOR]

Abstract The progress in catalysis research has recently led to new conversion pathways of cellulosic biomass to a range of tetrahydrofurans, which are potentially viable as biofuels. However, combustion behavior of these tetrahydrofurans is not well understood. Considering this as the main focus, the present study reports for the first time the formulation of a detailed chemical kinetic model of 3-methyltetrahydrofuran (3-MTHF). The developed model includes both its low- and high-temperature chemistry and is able to explain the reason for higher reactivity of 3-MTHF than 2-methyltetrahydrofuran (2-MTHF). In order to assess the prediction capability of the proposed model, ignition delay measurements of 3-MTHF were performed in two different combustion reactors, rapid compression machine and shock tube. The ignition delay times were measured for 3-MTHF/air mixtures spanning a wide range of temperatures from 615 K to 1256 K, at pressures of 10 bar, 20 bar, and 40 bar, and varying equivalence ratio of 0.5, 1.0, and 2.0. The proposed model compares well against new and already existing experimental data. A detailed chemical analysis of the auto-ignition of 3-MTHF reveals that the presence of two secondary α -carbon centers and hence four α -C–H bonds leads to its substantially higher reactivity in comparison to its structural isomer 2-MTHF, which possesses one secondary α - and one tertiary α -carbon center. [ABSTRACT FROM AUTHOR]

Herein we present a high yield 2-methylfuran production process with the required features to be implemented in a future integrated biorefinery. The strategy is based on the right solvent selection, 2-methyltetrahydrofuran, which i) can be used to extract the reactant, furfural, from the aqueous solution obtained after corncob biomass hydrolysis; ii) allows for highly selective 2-methylfuran production form furfural with up to 80% yields and iii) presents suitable biofuel properties in the gasoline range. Using this innovative approach, two energy intensive separation steps are avoided: the initial furfural purification and the final solvent/product complete separation. Further benefits of this process arise from the developed low-cost, selective, and reusable Cu-Co/γ-Al 2 O 3 catalyst. [ABSTRACT FROM AUTHOR]

Abstracts 2-methyltetrahydrofuran (MTHF) has been considered as a potential biofuel candidate for the renewable feedstock and attractive properties. In this study, the spherically propagating flames of the MTHF/isooctane-air mixtures in different blending ratios were investigated at elevated temperatures and pressures over equivalence ratios of 0.8–1.5 in a constant volume chamber using high-speed photography technique. Laminar burning velocities were calculated through nonlinear method and correlated by mixing rules as a function of initial temperature, pressure, equivalence ratio, and blending ratio. To investigate the influence of the potential interaction between MTHF and isooctane, a detailed model was established by merging the models of the two fuels and validated against laminar burning velocity, ignition delay times and flame structure. The laminar flame velocities of MTHF were observed to increase with initial temperature while the flame velocities decrease with increase in pressure. Kinetic analysis indicates that the major consumption pathways for MTHF are through H abstraction reactions at 2 and 5 sites. The H abstraction reactions at methyl group are less competitive. Unsaturated hydrocarbons and aldehydes are produced in high concentration and are the main stable intermediates of MTHF combustion. The laminar burning velocity is sensitive to the reactions of small radicals and some intermediates such as propylene and ethylene. The laminar burning velocities of MTHF/isooctane blends increase with MTHF blending ratio. The influence of blending ratio on laminar burning velocity should attribute to the chemical factors, rather than thermal or diffusion factors. MTHF oxidation generates less proportion of propylene and higher fractions of H, OH than isooctane, reflecting positive chemical effects on laminar burning velocity as MTHF blended. According to the instability analysis, the Markstein length and critical radius shows similar flame instability among different blending ratios. [ABSTRACT FROM AUTHOR]

A biphasic pretreatment was adopted to disturb the recalcitrant structure of bamboo for further enzymatic hydrolysis and to obtain easily valorized lignin by-product. The biphasic system consisted of biomass-derived chemicals—2-methyltetrahydrofuran and oxalic acid as well as water, and the reactions were conducted at 120–180 °C for 20 min. The treatment resulted in notable removal of hemicelluloses and lignin. After the pretreatment, the cellulose conversion rate during enzymatic hydrolysis was enhanced by 6.7-fold as compared to the unpretreated raw material. Comprehensive analysis of the lignin product indicated that it exhibited representative structure (such as β-O-4, β-β linkages) as compared to native lignin, contained a very low amount of contaminated sugars (0.67–2.39%), and had a relatively medium molecular weight (Mw 2240–3730 g/mol) and good solubility in many organic solvents. This indicated that the lignin showed great potential application in conversion into materials and liquid fuels. [ABSTRACT FROM AUTHOR]

The activity of a series of impregnated Ni-Cu/Al 2 O 3 catalysts was evaluated for the production of 2-methyltetrahydrofuran (MTHF) from γ-valerolactone using 2-butanol as solvent. These catalysts evidenced that their activities depend more on the metal phase nature then on the metal sites dispersion, achieving three times higher Normalized MTHF Productivity (NMP) the samples with the highest amounts of the Ni-Cu alloy. In addition, the activity of those high Ni-Cu alloy containing samples showed to be limited by their low surface acidity. The promotion of the alloy formation, acidity and metal-acid sites proximity was achieved by a co-precipitation method. This new catalyst, calcined and reduced at 450 °C, allows a MTHF yield of 64% after 5 h. The tested catalysts showed deactivation by carbon deposition which could be overcome by intermediate regeneration between runs. The best catalyst showed stable > 54% MTHF yield for three consecutive runs. [ABSTRACT FROM AUTHOR]

2-methyltetrahydrofuran, an ecofriendly substitute for traditional organic solvents, was employed to construct cosolvent system for synthesis of (S)-3-chloro-1-phenylpropanol by permeabilized recombinant Escherichia coli containing the YOL151W reductase and Escherichia coli containing d -glucose dehydrogenase to regenerate NADPH. By optimization, 30 mM 3-chloro-1-phenyl-1-propanone could be efficiently converted to (S)-3-chloro-1-phenylpropanol with a yield of 98.6% and enantiomeric excess of more than 99.9% in 3% (v/v) of 2-methyltetrahydrofuran, 2% (v/v) of Triton X-100 and Tris-HCl buffer coslovent system. The application of 2-methyltetrahydrofuran has proved to be a promising cosolvent for asymmetric reduction of water-insoluble prochiral ketones. [ABSTRACT FROM AUTHOR]

A combined process for carotenoids extraction and efficient bioenergy recovery from the wet microalgae biomass is proposed. High added-value products could thus be extracted prior a hydrothermal gasification of the algal biomass into synthetic natural gas. The economic sustainability of biofuel production from algal biomass as well as the large energy demands of microalgae cultivation and harvesting is addressed in this paper. Two green solvents, ethanol and 2-methyltetrahydrofuran (MTHF), were used to achieve the maximum extractability of selected carotenoids. Pure MTHF was tested for the first time as an alternative renewable solvent for carotenoid extraction from wet biomass and promising results were obtained (30 min at 110 °C), with 45% of total carotenoids being extracted. The energy content of the residual biomass corresponds to a High Heating Value (HHV) of 18.1 MJ/kg. With a 1:1 mixture of both MTHF and ethanol, more carotenoids were extracted from wet biomass (66%) and the remaining HHV of the residual biomass was 15.7 MJ/kg. The perspectives of combined carotenoid extraction and energy recovery for a better microalgae valorization are discussed. [ABSTRACT FROM AUTHOR]

The oxidation of 2-methyltetrahydrofuran (2-MTHF) has been experimentally studied in a rapid compression machine. The ignition delays of stoichiometric 2-MTHF/O 2 /inert mixtures were measured for a wide range of conditions: Top dead center pressure ranging from 0.3 to 2.1 MPa and core gas temperatures between 640 K and 900 K. Two-stage ignition is observed for temperatures between 685 K and 790 K, leading to a deviation from Arrhenius behavior of the evolution of ignition delays with temperature. Sampling of the reacting mixture was performed for different times between the top dead center and the ignition. Stable reaction intermediates were separated by gas chromatography, identified by mass spectrometry and quantified with a flame ionization detector. More than 20 species were identified and used to identify major reaction pathways. Among species of importance, 2-methyl-dihydrofurans, 2-methylfuran, methyldihydrofuranones, 1-cyclopropanylethanone, 3-penten-2-one and methylvinylketone were detected. Mole fraction profiles were obtained and used alongside first stage and total ignition delays to validate a detailed kinetic model for the oxidation of 2-MTHF. The resulting model takes in account 507 species involved in 2425 reactions. The validity of this model was extended to the high temperature range using existing ignition delays and low pressure laminar flame speciation data. [ABSTRACT FROM AUTHOR]

Efficient lipase-mediated research work was successfully exploited for synthesizing potential 6″- O -acyl-polydatin prodrugs in biomass-derived 2-methyltetrahydrofuran (2-MeTHF). The results of the enzyme recognitions of nine acyl donors evidently demonstrated that the position and number of the C C double bond in acyl chains profoundly influenced the behavior of the enzyme, which could be attributable to the resonance effect between the double bond and carbonyl group. Further investigations showed that introducing various acyl groups into the polydatin apparently enhanced its pH stability and 1-octanol-water partition coefficient (log P ). With regard to the human cervical cancer siHa cell apoptosis by a flow cytometry assay, the lipophilic 6″- O -sorboyl-polydatin exhibited improved apoptosis-inducing capability than the parent drug. The presence of the more lipophilic sorboyl chain in the acylated derivative could account for this. [ABSTRACT FROM AUTHOR]

The present paper elucidates oxidation behavior of 2-methyltetrahydrofuran (2-MTHF), a novel second-generation biofuel. New experimental data sets for 2-MTHF including ignition delay time measurements in two different combustion reactors, i.e. rapid compression machine and high-pressure shock tube, are presented. Measurements for 2-MTHF/oxidizer/diluent mixtures were performed in the temperature range of 639 − 1413 K, at pressures of 10, 20, and 40 bar, and at three different equivalence ratios of 0.5, 1.0, and 2.0. A detailed chemical kinetic model describing both low-and high-temperature chemistry of 2-MTHF was developed and validated against new ignition delay measurements and already existing flame species profiles and ignition delay measurements. The mechanism provides satisfactory agreement with the experimental data. For identifying key reactions at various combustion conditions and to attain a better understanding of the combustion behavior, reaction path and sensitivity analyses were performed. [ABSTRACT FROM AUTHOR]

Kinetic analyses were performed based on the experimental results of ignition delay times of 2-methyltetrahydrofuran (2-MTHF) using shock tube technique at temperatures of 1050–1800 K, equivalence ratios of 0.5–2.0, fuel mole concentrations of 0.25–1.0%, and pressures of 1.2–10 atm. A new kinetic model of 2-MTHF oxidation named Mech III was established according to the analysis of simulation using two published models (Mech I from Ravi Fernandes group and Mech II from Battin-Leclerc group) and the experimental data in this work. Comparison between simulation and experimental data indicated that Mech II shows remarkable under-prediction while Mech I gives a good agreement with ignition delay times under most conditions except for underprediction on fuel-rich mixtures at relative low temperature around 1250 K. Sensitivity analysis indicated that both models underestimated ignition delay times for the reactions of C 0 -C 4 molecules, so Mech III was formed by introducing such reactions and can demonstrate improved simulation performance under all conditions. Reaction pathway analysis of Mech III showed that 2-MTHF is mainly consumed through fuel decomposition at high temperatures (around 1550 K), and H-atom abstraction reactions at lower temperatures (around 1250 K), respectively. The comparative experimental and kinetic study between 2-MTHF and 2-methylfuran (MF) indicated that 2-MTHF has higher ignition delay times under the same conditions in this work, while the disparity decreases as the temperature increases, and 2-MTHF produces less soot precursors under high temperature conditions. [ABSTRACT FROM AUTHOR]

The demand for biofuels increases due to concerns regarding greenhouse gas emissions and depletion of fossil oil reserves. Many substances identified as potential biofuels are solvents or already used as flavors or fragrances. Although humans and the environment may be readily exposed little is known regarding their (eco)toxicological effects. In this study, the three potential biofuels ethyl levulinate (EL), 2-methyltetrahydrofuran (2-MTHF) and 2-methylfuran (2-MF) were investigated for their acute embryo toxicity and teratogenicity using the fish embryo toxicity (FET) test to identify unknown hazard potentials and to allow focusing further research on substances with low toxic potentials. In addition, two fossil fuels (diesel and gasoline) and an established biofuel (rapeseed oil methyl ester) were investigated as references. The FET test is widely accepted and used in (eco)toxicology. It was performed using the zebrafish Danio rerio , a model organism useful for the prediction of human teratogenicity. Testing revealed a higher acute toxicity for EL (LC 50 : 83 mg/L) compared to 2-MTHF (LC 50 : 2980 mg/L), 2-MF (LC 50 : 405 mg/L) and water accommodated fractions of the reference fuels including gasoline (LC 50 : 244 mg DOC/L). In addition, EL caused a statistically significant effect on head development resulting in elevated head lengths in zebrafish embryos. Results for EL reduce its likelihood of use as a biofuel since other substances with a lower toxic potential are available. The FET test applied at an early stage of development might be a useful tool to avoid further time and money requiring steps regarding research on unfavorable biofuels. [ABSTRACT FROM AUTHOR]

• 2-Methyltetrahydrofuran production from furfural using a trimetallic catalyst. • Cu nanoparticles on the Hβ surface became smaller after doping Ni or Re. • The adsorption configurations of reactants on the catalyst were determined. • The hydrogenation and hydrodeoxygenation sites of the catalyst were determined. The direct conversion of furfural (FUR) to 2-methyltetrahydrofuran (2-MTHF) was investigated over a trimetallic CuNiRe/Hβ catalyst. Under optimal reaction conditions at 240 °C under 3 MPa H 2 for 1 h, almost complete conversion of FUR and high-yield of 2-MTHF (81 %) was achieved. This is the highest yield reported for the direct conversion of FUR to 2-MTHF. HR-TEM demonstrated that the growth of Cu nanoparticles (NPs) on the surface of Hβ was inhibited after loading Ni or Re resulted in the smaller Cu particle size and better hydrogenation and hydrodeoxygenation activity. H 2 -TPR characterization exhibited that the reducibility of bimetallic and trimetallic catalysts was higher than that of monometallic catalysts·NH 3 -TPD explained that Hβ acid sites mainly contributed to FUR deoxygenation. The adsorption configurations of FUR, furfuryl alcohol (FOL) and 2-methylfuran (2-MF) on the catalyst were revealed by ATR-IR. Catalyst evaluation and control experiments proved that FUR was first hydrogenated to FOL, followed by hydrodeoxygenation to 2-MF, and finally hydrogenated to 2-MTHF catalyzed by the combination of three metals. [ABSTRACT FROM AUTHOR]

• Active and selective bimetallic Ni-Co catalysts allow for high yield 2-MTHF production. • Addition of Ni in small amount to Co catalyst strongly boosts the furanic fuel production. • 2-MTHF production is strongly impacted by Ni-Co composition and preparation conditions. • Ni surface availability and acidity are key-factors driving the catalyst performances. • Ni-Co catalysts were reusable over 5 test cycles. The sustainable production of environmentally-friendly alternative fuels from renewable resources is one of the worldwide high-prospect strategies for future biorefinery schemes. 2-methyltetrahydrofuran (2-MTHF) that can be obtained from renewable sources such as lignocellulosic biomass is considered as an ideal green fuel competitive to benchmarks products due to high-value properties like high energy density. In our work we showed that bimetallic Ni-Co/γ-Al 2 O 3 catalysts with an appropriate amount of Ni are worth robust, reusable and cheap earth-abundant non-noble metals-based catalysts enabling the high yield production of 2-MTHF. The factors allowing the activity to be strongly boosted compared to the monometallic counterparts while keeping a high selectivity to the targeted 2-MTHF product were identified and discussed. Among the key factors we identified the role of the Ni-Co interaction allowing the Ni availability at the surface of the catalyst to be enhanced. Additionally, the surface acidity was recognized as another important factor. Silica supported catalysts were selective towards the 1,4-pentanediol (1,4-PDO) intermediate obtained by GVL dehydration, while more acidic γ-Al 2 O 3 was pushing the reaction further towards 2-MTHF. The synthesis parameters were optimized in terms of reduction temperature (500 °C) and Ni:Co ratio (1:4) on the most active γ-Al 2 O 3 supported catalyst. [ABSTRACT FROM AUTHOR]

Highlights: [•] Hydrogenation of 2-MF was performed over noble and base metal catalysts at various reaction conditions. [•] The Pd/C catalyst was highly active for the ring saturation at low reaction temperatures. [•] The base metal catalysts were active for both furan ring opening and saturation reactions. [•] 2-PN was the main hydrogenation product over all the catalysts at high reaction temperatures. [ABSTRACT FROM AUTHOR]

• The stability of violet phosphorene (violet PNS) is studied from the formation energy and found to be stable. • The energy band gap of violet PNS is observed to be 1.846 eV. • The violet PNS is used as base material to adsorb 2-Methyltetrahydrofuran (Me-THF) and tetrahydrofuran (THF) • The electronic properties of violet PNS changes owing to THF and Me-THF molecular adsorption. The allotrope of phosphorous, namely violet phosphorene (violet PNS) is investigated for the possible application as a chemical nanosensor. Initially, the stability of violet PNS is studied from the formation energy, which is observed to be −5.311 eV/atom confirming the stable geometry of violet PNS. The violet PNS is used as a base material to adsorb 2-Methyltetrahydrofuran (Me-THF) and tetrahydrofuran (THF). The adsorption energy of THF and Me-THF on violet PNS exhibits physisorption. The electronic particulars of violet PNS owing to THF and Me-THF are analysed based on the band structure, projected density of states (PDOS), and electron density difference results. Besides, the decrease in the energy band gap of violet PNS is noticed due to THF and Me-THF molecular adsorption. The chemi-resistive character of violet PNS is ensured based on average energy gap variations. Thus, the results support the deployment of violet PNS as a proper base substrate for THF and Me-THF detection. [ABSTRACT FROM AUTHOR]

Abstract: Applicability of 2-methyltetrahydrofuran for olefin metathesis was examined with a set of ruthenium Hoveyda-type second generation catalysts. Influence of temperature was studied and the results were compared with those obtained in classical solvents for metathesis: dichloromethane and toluene. [Copyright &y& Elsevier]

Abstract: Clean combustion processes are of paramount importance in the transition of the energy system towards increased sustainability. In an attempt to partially replace conventional fossil fuels, bio-derived oxygenates attract rising attention as alternative transportation fuels. Among this class of fuels, cyclic structures that can be derived from cellulosic biomass are particularly interesting. Here we present a study of premixed, laminar low-pressure flames of 2-methyltetrahydrofuran (2-MTHF) with an equivalence ratio of ϕ =1.7 at 40mbar. Time-of-flight molecular-beam mass spectrometry (MBMS) with electron ionization (EI) was used to analyze and quantify mole fraction profiles of reactants, products, and most intermediate species including radicals involved in the combustion process. As a valuable complement, MBMS using single-photon ionization (PI) by vacuum ultraviolet radiation permitted isomer identification as well as independent concentration information under similar flame conditions. A detailed combustion model for 2-MTHF was developed, and the flame structure and species information were examined in conjunction with these experiments. [Copyright &y& Elsevier]

Abstract: A total of nine lipases and three proteases were tested for enzymatic regioselective acylation(s) of cordycepin with vinyl acetate in organic media. The highest conversion with better initial reaction rate was achieved with immobilized Candida antarctica lipase B (Novozym 435). An eco-friendly solvent 2-methyltetrahydrofuran (MeTHF) was thought to be the most suitable reaction medium. Novozym 435 was found to be a useful biocatalyst for the 25-g scale syntheses of cordycepin acetate (96.2% isolated yield), and the biocatalyst displayed excellent regioselectivity and high operational stability during the transformation. The 5′-substituted cordycepin derivative was the sole detectable product from each acylation reaction. Novozym 435 could be recycled for the synthesis of cordycepin derivative on a 25-g scale and 63% of its original activity was maintained after being reused for 7 batches. MeTHF could be considered as an eco-friendly solvent for the large scale use in biotransformation. [Copyright &y& Elsevier]

Abstract: 2-Methyltetrahydrofuran has recently been described as a promising and green solvent. Herein, it was successfully used as the reaction medium for enzyme-mediated transphosphatidylation of phosphatidylcholine with l-serine with the aim of phosphatidylserine synthesis for the first time. Our results indicated that as high as 90% yield of phosphatidylserine could be achieved after 12h combined with no byproduct (phosphatidic acid) forming. The present work accommodated a facilely and efficiently enzymatic strategy for preparing phosphatidylserine, which possessed obvious advantages over the reported processes in terms of high efficiency and environmental friendliness. This work is also a proof-of-concept opening the use of 2-methyltetrahydrofuran in biosynthesis as well. [Copyright &y& Elsevier]

Abstract: 2-Methyltetrahydrofuran (MeTHF), a biomass-derived compound, is a promising medium for biocatalysis and organometallic reactions. The regioselective acylation of 8-chloroadenosine (8-Cl-Ado) and its analogs was carried out in MeTHF with immobilized Penicillium expansum lipase. The lipase displayed more than twofold higher catalytic activity and much better thermostability in MeTHF than in other organic solvents and co-solvent systems. The optimum reaction medium, enzyme dosage, molar ratio of viny ester to nucleoside and reaction temperature for the enzymatic acylation of 8-Cl-Ado were MeTHF, 25U/mL, 7.5 and 35°C, respectively, under which the desirable 5′-O-undecylenoyl-8-Cl-Ado was obtained with a yield of 95% and a regioselectivity of >99% in 3h. In addition, the lipase catalyzed regioselective undecylenoylation of other purine nucleosides, producing 5′-undecylenic acid esters with moderate to high yields (63–94%) and excellent 5′-regioselectivities (94–>99%). Use of biomass-derived solvents might open up novel opportunities for sustainable and greener biocatalytic processes. [Copyright &y& Elsevier]

• A bimetallic catalyst NiCo presented efficient hydrogenolysis of levulinic acid to 2-methyltetrahydrofuran. • The NiCo catalysts with different Ni/Co ratios showed distinct performance due to varied surface properties of catalysts. • Molecular dynamics simulations highlighted a high probability of forming a close position between two hydroxyl groups of the intermediate 1,4-pentanediol in a 2-propanol medium than other mediums. The production of furanic biofuel 2-methyltetrahydrofuran (2-MTHF) has been studied by hydrodeoxygenation of biomass-derived levulinic acid (LA) over bimetallic NiCo/γ-Al 2 O 3 catalyst. The contents of Ni and Co in NiCo/γ-Al 2 O 3 were investigated. The Ni 5 Co 25 /γ-Al 2 O 3 catalyst gave high activity in hydrodeoxygenation of LA with a 73.4% yield of 2-MTHF under optimal conditions. The crystal phase, valence states, acidity and basicity of catalysts were measured by multiple characterizations to understand the relationships among 2-MTHF yields and catalyst properties. XPS characterization revealed that the number of metal oxides increased on bimetallic catalysts while the reduced metals occupied on monometallic catalysts. The bimetallic catalysts also presented increased acidity than that of monometallic catalysts. These distinct properties were also observed among bimetallic catalysts with different contents of Ni and Co, which were responsible for different performances. Besides, the solvent effect on the structure of 1,4-pentanediol, which was further converted to 2-methyltetrahydrofuran, was disclosed by molecular dynamics simulations. [Display omitted] Insights into Ni/Co ratio of bimetallic NiCo catalyst and solvent effect on efficient hydrogenolysis of levulinic acid to furanic biofuel 2-methyltetrahydrofuran [ABSTRACT FROM AUTHOR]

Excess molar enthalpies, measured at 298.15 K in a flow microcalorimeter, are reported for the ternary mixtures (tetrahydrofuran + diisopropyl ether + n-heptane) and (tetrahydrofuran + 2-methyltetrahydrofuran + n-heptane). Smooth representations of the results are described and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. The latter are compared with diagrams obtained when the model of Liebermann and Fried is used to estimate the excess enthalpies of the ternary mixtures from the physical properties of the components and their binary mixtures. [Copyright &y& Elsevier]

• The dilution effect on laminar flame characteristics of 2-MTHF was investigated. • The effect of CO 2 , N 2 and helium on LBVs of 2-MTHF-air was compared. • The stabilizing abilities of CO 2 , N 2 and helium were compared and analyzed. • The dilution effect of CO 2 , N 2 and helium on critical flame size was evaluated. Recent investigations have indicated that 2-methyltetrahydrofuran (2-MTHF) can be a potential alternative fuel, owing to its renewability and environmentally friendly properties. In this study, the effects of carbon dioxide (CO 2), nitrogen (N 2), and helium (He) dilution on the laminar burning velocity (LBV) and cellular instability of 2-MTHF-air flames were investigated experimentally and kinetically at a temperature of 423 K, a pressure of 5 bar, equivalence ratios (ϕ) of 0.7–1.5, and diluent ratios of 0–15%. The results illustrated that CO 2 exhibited the strongest ability to reduce the LBVs, followed by N 2 and He. The effective Lewis number ( Le eff ) of the He diluted 2-MTHF-air flames increased as more He was added to the reactant mixture, thereby indicating that the intensity of diffusive-thermal instability could be diminished by He dilution. In contrast, Le eff was insensitive to CO 2 and N 2 dilution. The flame thickness increased and the density ratio decreased as the diluent ratio increased, indicating that all three diluents suppressed the hydrodynamic instability of 2-MTHF-air flames. The relative magnitudes of the stabilizing abilities of these diluents were in the order CO 2 > N 2 > He. The stability analysis indicated that the monotonically decreasing critical Péclet number and non-monotonically altered flame thickness caused a non-monotonic variation in the theoretical critical flame radius of 2-MTHF-air flames versus ϕ. The most chaotic state occurred at approximately ϕ = 1.3 under all test conditions. Notably, CO 2 and He exhibited a similar ability to delay the onset of cellular instability, whereas N 2 demonstrated a weaker ability to do so. [ABSTRACT FROM AUTHOR]

Abstract: Silica-supported piperazine was found to be an efficient catalyst for aldol reactions of aromatic aldehydes and ketones with straightforward product isolation and catalyst reuse. Furthermore, the catalyst is active in Knoevenagel-type reactions to afford coumarin derivatives, using 2-methyltetrahydrofuran (2-MeTHF) as a novel bio-based solvent. [Copyright &y& Elsevier]

• Response surface methodology is used to optimise lipid extractions from fresh BSF. • The wet extraction with 2-MeTHF extracts a similar amount compared to Soxhlet. • More lipids are extracted with the green solvent 2-MeTHF in comparison to hexane. • The fatty acid profiles of hexane and 2-MeTHF extracts do not differ significantly. • The more polar 2-MeTHF extracts significantly higher quantities of phospholipids. While black soldier fly larvae (BSFL, Hermetia illucens) have the potential to become a renewable, industrial feedstock; lipid extractions are typically performed with hexane. Green solvents, however, are gaining more popularity to replace these harmful solvents such as hexane. In this study, the green solvent 2-methyltetrahydrofuran (2-MeTHF) was compared with hexane for extracting lipids from fresh BSFL at moderate temperature. Response surface methodology was used to investigate these wet extractions with a Soxhlet extraction as benchmark. Two sets of optimal process settings were predicted and validated for (1) maximising solvent efficiency and (2) maximising lipid recovery. The resulting extracts were characterised by their fatty acid profile and lipid class composition. The results of the benchmark extraction (Soxhlet) showed that 2-MeTHF could extract significantly more lipids from dried BSFL than hexane (43.23 vs. 40.34 g lipids/100 g DM). No significant difference was found between the maximum solvent efficiencies of hexane and 2-MeTHF. By performing the wet extraction with 2-MeTHF at 45 °C with 15 w/w % fresh BSFL, 40 w/w % 2-MeTHF, and 45 w/w % water; the highest lipid recovery was obtained (94.9 ± 1.8% of total BSFL lipids). These results indicated that the wet extraction was able to extract a similar amount of lipids compared to the Soxhlet extraction. Although the fatty acid profiles did not differ between extraction conditions, 2-MeTHF extracted a higher quantity of free fatty acids and valuable phospholipids compared to hexane. Consequently, the wet lipid extraction with 2-MeTHF can be considered a suitable, more ecologic alternative for the conventional extraction of dried BSFL with hexane. [ABSTRACT FROM AUTHOR]

• A highly compact and robust tetrahydrofurans chemical kinetic mechanism was developed with 56 species and 183 reactions. • Genetic Algorithm was introduced to achieve self-adaptive tuning of Arrhenius pre-exponential factor of reactions. • Good performance was highlighted by the optimized mechanism against existing experimental results. This work presents a compact and robust chemical reaction mechanism for modeling the combustion of saturated furans including tetrahydrofuran, 2-methyltetrahydrofuran and 2-buthyltetrahydrofuran under engine relevant conditions. A decoupling method is adopted to construct the mechanism. The oxidation reaction for the small species is described by a mature and detailed H 2 /CO/C 1 sub-mechanism, based on which the skeletal sub-mechanisms for tetrahydrofuran, 2-methyltetrahydrofuran and 2-buthyltetrahydrofuran are incorporated via a compact yet robust C 2 -C 3 sub-mechanism. The sub-mechanisms for the three tetrahydrofuranic fuel components are selected from the detailed chemical mechanisms in the literature via a series of species rate of production analysis, sensitivity analysis, isomer lumping and reaction lumping. The Arrhenius pre-exponential A factors for these selected reaction pathways are then optimized via a single objective genetic algorithm. The resulting mechanism is rather compact consisting of only 56 species among 183 reactions. The performance of the developed mechanism for predicting the combustion chemistry for the three fuel components has been evaluated against the experimental measurements in the literature. Reasonable agreement between the predicted ignition delay times, speciation profiles and laminar flame speeds with the experimental data is achieved for all the cases considered, indicating the high accuracy and robustness of the developed mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • One-pot conversion of furfural into 2-methyltetrahydrofuran is achieved. • 87 % yield of 2-methyltetrahydrofuran is obtained with non-precious metals. • Lewis acid sites are crucial for furfural hydrodeoxygenation to 2-methylfuran. 2-methyltetrahydrofuran, a biomass-derived chemical, is an important solvent with broad applications in organic chemistry. In this study, one-pot conversion of furfural into 2-methyltetrahydrofuran over non-precious metal catalysts was achieved by two-stage packing in a single reactor. The first stage converted furfural into 2-methylfuran over Co-based catalysts, and the second stage converted 2-methylfuran into 2-methyltetrahydrofuran over Ni-based catalysts. In order to reveal the reaction pathway and mechanism of this process, the hydrogenation reactions of 2-methylfuran, furfuryl alcohol, and tetrahydrofurfuryl alcohol were also carefully investigated. It is discovered that the conversion of furfural into 2-methylfuran could be catalyzed by Lewis acid sites, which was confirmed by a correlation between 2-methylfuran production rate and Lewis acid site density. Also, a mechanism on the direct conversion of furfural into 2-methylfuran without forming furfuryl alcohol as the intermediate is proposed. The experimental results of 2-methylfuran, furfuryl alcohol, and tetrahydrofurfuryl alcohol hydrogenation/hydrodeoxygenation over various catalysts provided valuable information on the future design of 2-methyltetrahydrofuran catalyst. [ABSTRACT FROM AUTHOR]

• Hydrogenation of γ-valerolactone was investigated in the vapor phase. • Cu/Al 2 O 3 exhibited a high activity under mild reaction conditions with a relatively low H 2 pressures. • Selectivity to 2-methyltetrahydrofuran was improved by calcination of Cu/Al 2 O 3 up to 700 °C. • Cu/Al 2 O 3 with a high acid density was preferable for the formation of 2-methyltetrahydrofuran. • 98.9 % selectivity with a conversion of 98.5% was achieved at 200 °C and 1.5 MPa. Vapor-phase hydrogenation of γ-valerolactone (GVL) to form 2-methyltetrahydrofuran (2-MTHF) was studied over various non-noble metal catalysts under mild reaction conditions. Cu/Al 2 O 3 catalyst exhibited a high catalytic performance, and the calcination of Cu/Al 2 O 3 significantly affected the product selectivity. The Cu/Al 2 O 3 calcined at 700 °C with a high acid density was the most selective for the formation of 2-MTHF. The calcination of Cu/Al 2 O 3 at 800 °C or higher led to the formation of CuAl 2 O 4 phase with low acidity, which was not preferable for the formation of 2-MTHF. The effects of the reaction conditions were studied in detail: a 2-MTHF selectivity of 98.9% with a GVL conversion of 98.5% was achieved at 200 °C, an H 2 pressure of 1.5 MPa, and a weight hourly space velocity of 0.7 h−1 without catalytic deactivation. [ABSTRACT FROM AUTHOR]

This study investigated the non-catalyzed solvolysis of sulphur free organosolv lignin using mixtures of organic solvents (methanol, ethanol and 2-methyltetrahydrofuran) and water with emphasis on the novel biphasic 2-methyltetrahydrofuran (2-MTHF)/water reaction medium. The effect of co-solvents, co-solvent-to-water ratio and temperature were studied. 2-MTHF proved to be effective co-solvent with water that significantly suppressed char formation and also demonstrated promising protection effect on monoaromatic compounds. The yield of solvolyzed lignin (SL) and char were in the range of 40.0–88.6% and 10.4–0.1% respectively, based on initial amount of dried lignin. The yield of monoaromatics maximized to 67.2 mg g−1 of lignin at 310 °C and 60 min with syringol, syringaldehyde, 4-methylsyringol, 1,2,3-trimethoxy-5-methyl benzene and guaiacol as the main compounds. • Non-catalytic solvolysis of sulphur free organosolv lignin using organic co-solvent and water • Special emphasis on 2-methyltetrahydrofuran/water as a novel reaction medium for lignin solvolysis. • Suppression of char during lignin depolymerization to <1 wt% [ABSTRACT FROM AUTHOR]