The pyrolytic and oxidative behaviour of the biofuel 2,5-dimethylfuran (25DMF) has been studied in a range of experimental facilities in order to investigate the relatively unexplored combustion chemistry of the title species and to provide combustor relevant experimental data. The pyrolysis of 25DMF has been re-investigated in a shock tube using the single-pulse method for mixtures of 3% 25DMF in argon, at temperatures from 1200-1350 K, pressures from 2-2.5 atm and residence times of approximately 2 ms.Ignition delay times for mixtures of 0.75% 25DMF in argon have been measured at atmospheric pressure, temperatures of 1350-1800 K at equivalence ratios (ϕ) of 0.5, 1.0 and 2.0 along with auto-ignition measurements for stoichiometric fuel in air mixtures of 25DMF at 20 and 80 bar, from 820-1210 K. This is supplemented with an oxidative speciation study of 25DMF in a jet-stirred reactor (JSR) from 770-1220 K, at 10.0 atm, residence times of 0.7 s and at ϕ = 0.5, 1.0 and 2.0.Laminar burning velocities for 25DMF-air mixtures have been measured using the heat-flux method at unburnt gas temperatures of 298 and 358 K, at atmospheric pressure from ϕ = 0.6-1.6. * address: Combustion Chemistry Centre, National University of Ireland, Galway, University Road Galway, Ireland. Phone: +353-91-494087. k.somers1@nuigalway.ie, URL: http://c3.nuigalway.ie/ (Kieran P. Somers).. Electronic Supplementary Information Electronic supplementary information includes:• Tabulations of all new experimental data • Pressure-time profiles for high pressure shock tube experiments and volume-time profiles used for corresponding simulations• A description of the optimized group additivity rules for substituted furans •The chemkin format kinetic mechanism, thermodynamic and transport files• A list of species structures and names for interpretation of kinetic mechanism and sensitivity analysis diagrams These laminar burning velocity measurements highlight inconsistencies in the current literature data and provide a validation target for kinetic mechanisms.A detailed chemical kinetic mechanism containing 2768 reactions and 545 species has been simultaneously developed to describe the combustion of 25DMF under the experimental conditions described above. Numerical modelling results based on the mechanism can accurately reproduce the majority of experimental data. At high temperatures, a hydrogen atom transfer reaction is found to be the dominant unimolecular decomposition pathway of 25DMF. The reactions of hydrogen atom with the fuel are also found to be important in predicting pyrolysis and ignition delay time experiments.Numerous proposals are made on the mechanism and kinetics of the previously unexplored intermediate temperature combustion pathways of 25DMF. Hydroxyl radical addition to the furan ring is highlighted as an important fuel consuming reaction, leading to the formation of methyl vinyl ketone and acetyl radical. The chemically activated recombination of HȮ 2 or CH 3 Ȯ 2 with the 5-methyl-2-furanylmethyl radical, forming a 5-methy...

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.

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Through the reaction of the amino­troponiminato­germylene monochloride complex [(Bu i 2ATI)GeCl] (1) with sodium pyrrolide, the stable N-germylene pyrrole complex [(Bu i 2ATI)GeNC4H4] (2) has been isolated. The reaction of compound 2 with thiophenol and selenophenol afforded the first germylene thio- and selenophenoxide complexes [(Bu i 2ATI)GeSPh] (3) and [(Bu i 2ATI)GeSePh] (4) through the substitution of the pyrrole moiety (NC4H4) with an EPh moiety (E = S (3), Se (4)), respectively. Interestingly, the chalcogenide derivatives of compound 2, such as the N-germathio­acylpyrrole complex [(Bu i 2ATI)Ge(S)NC4H4] (5) and N-germaseleno­acylpyrrole complex [(Bu i 2ATI)Ge(Se)NC4H4] (6), also underwent the aforementioned substitution reaction with thiophenol and selenophenol, resulting in the first examples of germa thioester complexes ([(Bu i 2ATI)Ge(S)SPh] (7) and [(Bu i 2ATI)Ge(Se)SPh] (8)) and germa selenoester complexes ([(Bu i 2ATI)Ge(S)SePh] (9) and [(Bu i 2ATI)Ge(Se)SePh] (10)), respectively. All the novel germanium compounds 3–10 have been unequivocally characterized through multinuclear NMR spectroscopy along with the germylene complex 2. Further, compounds 3–5 and 7–10 were characterized through single-crystal X-ray diffraction studies. The GeII–S and GeII–Se bond lengths in compounds 3 and 4 are 2.367(1) and 2.511(1) Å, respectively. The average GeIV–S and GeIV–Se bond lengths in germa thioester (7 and 8) and germa selenoester (9 and 10) complexes are 2.241(1) and 2.362(1) Å, respectively.

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The efficiency of spark-ignition engines is limited by the phenomenon of knock, which is caused by auto-ignition of the fuel-air mixture ahead of the spark-initiated flame front. The resistance of a fuel to knock is quantified by its octane index; therefore, increasing the octane index of a spark-ignition engine fuel increases the efficiency of the respective engine. However, raising the octane index of gasoline increases the refining costs, as well as the energy consumption during production. The use of alternative fuels with synergistic blending effects presents an attractive option for improving octane index. In this work, the octane enhancing potential of 2-methylfuran (2-MF), a next-generation biofuel, has been examined and compared to other high-octane components (i.e., ethanol and toluene). A primary reference fuel with an octane index of 60 (PRF60) was chosen as the base fuel since it closely represents refinery naphtha streams, which are used as gasoline blend stocks. Initial screening of the fuels was done in an ignition quality tester (IQT). The PRF60/2-MF (80/20 v/v%) blend exhibited longer ignition delay times compared to PRF60/ethanol (80/20 v/v%) blend and PRF60/toluene (80/20 v/v%) blend, even though pure 2-MF is more reactive than both ethanol and toluene. The mixtures were also tested *Revised Manuscript Click here to view linked References in a cooperative fuels research (CFR) engine under research octane number and motor octane number like conditions. The PRF60/2-MF blend again possesses a higher octane index than other blending components. A detailed chemical kinetic analysis was performed to understand the synergetic blending effect of 2-MF, using a well-validated PRF/2-MF kinetic model. Kinetic analysis revealed superior suppression of low-temperature chemistry with the addition of 2-MF. The results from simulations were further confirmed by homogeneous charge compression ignition engine experiments, which established its superior low-temperature heat release (LTHR) suppression compared to ethanol, resulting in better blending octane numbers. This work explores and provides a chemically sound explanation for the potential of 2-MF as an octane enhancer.

A first oxidation study of the novel lignocellulosic biofuel γ -valerolactone (GVL) has been performed in a low pressure premixed flat flame. A stoichiometric GVL/methane flame was investigated experimentally and numerically at a pressure of 50 Torr. The measurements include flame temperatures and species concentrations. Species profiles from online gas chromatography measurements are presented for about 40 species including oxygen, hydrogen, argon, carbon monoxide, carbon dioxide, water, hydrocarbon, and oxygenated species with separated isomers. The recent kinetic model for GVL pyrolysis of De Bruycker et al. (2016) was extended for oxidation and the resulting model shows good agreement with the experimental flame data. A reaction pathway analysis was performed, which elucidates the fuel specific oxidation pathways of GVL at the investigated conditions. Additionally, an enthalpy analysis of the flame was performed highlighting the consistency of the different measurement techniques.