Experimental and kinetic modeling study of i-butanol pyrolysis and combustion

i-Butanol (iC₄H₉OH) pyrolysis has been studied in a flow reactor with synchrotron vacuum ultraviolet photoionization mass spectrometry combined with molecular-beam sampling technique. The pyrolysis species were identified and their mole fractions were determined. Three pressures of 30, 150 and 760 Torr were selected to study the pressure effect of i-butanol chemistry. A detailed kinetic model consisting of 186 species and 1294 reactions was developed to simulate i-butanol high temperature chemistry. To enhance the accuracy, the model was further validated by the species profiles in shock tube pyrolysis, laminar premixed flames, oxidation data from jet-stirred reactor, ignition delay times, and flame speeds. Good agreement between the predicted and measured results was obtained.     

An experimental and kinetic modeling study of n-butanol combustion

n-Butanol is a fuel that has been proposed as an alternative to conventional gasoline and diesel fuels. In order to better understand the combustion characteristics of n-butanol, this study presents new experimental data for n-butanol in three experimental configurations. Species concentration profiles are presented in jet stirred reactor (JSR) at atmospheric conditions and a range of equivalence ratios. The laminar flame speed obtained in an n-butanol premixed laminar flame is also provided. In addition, species concentration profiles for n-butanol and n-butane in an opposed-flow diffusion flame are presented. The oxidation of n-butanol in the aforementioned experimental configurations has been modeled using an improved detailed chemical kinetic mechanism (878 reactions involving 118 species) derived from a previously proposed scheme in the literature. The proposed mechanism shows good qualitative agreement with the various experimental data. Sensitivity analyses and reaction path analyses have been conducted to interpret the results from the JSR and opposed-flow diffusion flame. It is shown that the main reaction pathway in both configurations is via H-atom abstraction from the fuel followed by β-scission of the resulting fuel radicals. Several unimolecular decomposition reactions are important as well. This study gives a better understanding of n-butanol combustion and the product species distribution.     

An experimental and modeling study of methyl propanoate pyrolysis at low pressure

Methyl propanoate (MP) pyrolysis in a laminar flow reactor was studied at low pressure (30 Torr) within the temperature range from 1000 to 1500 K. About 30 products were detected and identified in the pyrolysis process using the photoionization mass spectrometry, including H₂, CO, CO₂, CH₃OH, CH₂O, CH₂CO, C1 to C4 hydrocarbons and radicals (such as CH₃, C₂H₅ and C₃H₃). Their mole fraction profiles versus temperature were also measured. For the unimolecular dissociation reactions, the rate constants were calculated by high precision theoretical calculations. Based on the theoretical calculations and measured mole fraction profiles of pyrolysis species, a kinetic model of MP pyrolysis containing 98 species and 493 reactions was developed. The model simulates the primary decomposition process well with the calculated rate constants. According to the rate of production analysis, the decomposition pathways of MP and the formation channels of both oxygenated and hydrocarbon products were discussed. It is concluded that the main decomposition pathway is MP → CH₂COOCH₃ → CH₃CO + CH₂O → CO.     

Experimental and kinetic modeling study of pyrolysis and oxidation of n-decane

The pyrolysis of n-decane was investigated in a flow reactor at 5, 30, 150 and 760 Torr, and the oxidation of n-decane at equivalence ratios of 0.7, 1.0 and 1.8 was studied in laminar premixed flames at 30 Torr. In both experiments, synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) was used to identify combustion species and measure their mole fraction profiles. A new detailed kinetic model of n-decane with 234 species and 1452 reactions was developed for applications in intermediate and high temperature regions, and was validated against the experimental results in the present work. The model was also validated against previous experimental data on n-decane combustion, including species profiles in pyrolysis and oxidation in high pressure shock tube and atmospheric pressure flow reactor, jet stirred reactor oxidation, atmospheric pressure laminar premixed flame, counterflow diffusion flame and global combustion parameters such as laminar flame speeds and ignition delay times. In general, the performance of the present model in reproducing these experimental data is reasonably good. Sensitivity analysis and rate of production analysis were conducted to understand the decomposition processes of n-decane.     

Laminar flame speeds and kinetic modeling of hydrogen/chlorine combustion

In this study, laminar flame speeds at atmospheric pressure are accurately measured for H₂/Cl₂/N₂ mixtures at different equivalence ratios and N₂ mole fractions by the counterflow flame technique. A kinetic mechanism based on recently published and evaluated rate constants is developed to model these measured laminar flame speeds as well as the literature data on the concentrations of H₂, Cl₂, and HCl species in flat-burner flames and the ignition delay times from shock tube experiments. The kinetic model yields satisfactory comparison with these experimental data, and suggests that the reactions involving excited HCl(v) species and energy branching are not of substantial significance in combustion situations, and that the use of accurate elementary rate constants is instead crucial to the accuracy of the reaction mechanism.     

Combustion and pyrolysis of iso-butanol: Experimental and chemical kinetic modeling study

The first reaction mechanism for iso-butanol (372 species and 8723 reversible elementary reactions) pyrolysis and combustion that includes pressure dependent kinetics and proposes reaction pathways to soot precursors has been automatically generated using the open-source software package RMG. High-pressure reaction rate coefficients for important hydrogen abstraction reactions from iso-butanol by hydrogen, methyl and HO₂ were calculated using quantum chemistry at the CBS-QB3 level. The mechanism was validated with recently published iso-butanol combustion experiments as well as new pyrolysis speciation data under diluted and undiluted conditions from 900 to 1100 K at 1.72 atm representative of fuel rich combustion conditions. Sensitivity and rate of production analysis revealed that the overall good agreement for the pyrolysis species, and in particular for the soot precursors like benzene, toluene and 1,3-cyclopentadiene, depends strongly on pressure dependent reactions involving the resonantly stabilized iso-butenyl radical. Laminar flame speed, opposed flow diffusion flame speciation profiles, and autoignition are also well-captured by the model. The agreement with speciation profiles for the jet-stirred reactor could be improved, in particular for temperatures lower than 850 K. Flux and sensitivity analysis for iso-butanol consumption revealed that this is primarily caused by uncertainty in iso-butanol + OH, iso-butanol + HO₂ and the low temperature peroxy chemistry rates. Further theoretical and quantum chemical studies are needed in understanding these rates to completely predict the combustion behavior of iso-butanol using detailed chemistry.     

Experimental and kinetic modeling study of PAH formation in methane coflow diffusion flames doped with n-butanol

In order to understand the interactions between butanol and hydrocarbon fuels in the PAH formation, experimental and kinetic modeling investigations were combined to study methane laminar coflow diffusion flames doped with two inlet mole fractions of n-butanol (1.95% and 3.90%) in this work. Mole fractions of flame species along the flame centerline were measured using synchrotron VUV photoionization mass spectrometry. A detailed kinetic model of n-butanol combustion, extended from a recent published n-butanol model, was provided in this work to reproduce the fuel decomposition and the formation of benzene and PAHs in the investigated flames. Numerical simulations were performed with laminarSMOKE code, a CFD code specifically conceived to handle large kinetic mechanisms. The simulation results were able to follow the observed effects of n-butanol addition from the experimental results. In particular, unsaturated hydrocarbons, especially C6–C16 aromatics, were predicted satisfactorily. The reaction flux analysis revealed that benzene precursors, especially C3 radicals, increase significantly with increasing inlet mole fraction of n-butanol. This enhances the formation of phenyl and benzyl radicals, which are important PAH precursors. Reactions of benzyl, phenyl radicals and benzene with C2–C3 species are the major formation pathways for indene and naphthalene. And PAHs with more carbon atoms are dominantly formed from naphthyl and indenyl radicals.     

Effect of the equivalence ratio on the concentration of CH4/NO2/O2 combustion products

A chemical kinetic model for determining the mole fractions of stable and intermediate species for CH₄/NO₂/O₂ flames is developed. The model involves 30 different species in 101 chemical elementary reactions. The mole fractions of the species are plotted as a function of the distance from the surface of the burner. The effects of the equivalence ratio on the concentrations of CO, CO₂, N₂, NH₂, OH, H₂O, NO and NO₂ for lean CH₄/NO₂/O₂ flames in the post flame zone at 50 Torr are obtained. The flames are flat, laminar, one dimensional and premixed. The calculated concentration profiles as a function of the equivalence ratio and distance from the surface of the burner are compared with the experimental data. The comparison indicates that the kinetics of the flames are reasonably described by the developed model. The mole fraction of N₂, NH₂, OH, H₂O, CO₂ and CO increase while the mole fractions of NO and NO₂ decrease by increasing the equivalence ratio for lean flames. Copyright © 1999 John Wiley & Sons, Ltd.     

Kinetic modeling study of hydrogen addition to premixed dimethyl ether-oxygen-argon flames

The chemical composition of flames was examined systematically for a series of laminar, premixed low-pressure Dimethyl ether (DME)-oxygen-argon flames blended with hydrogen. The effects of hydrogen addition to the DME base flame were seen to result in interesting differences. The flame is analyzed with a comprehensive kinetic model that combines the chemistries of hydrogen and DME combustion. The results indicated that the reduction of CH₃OCH₃ mole fraction in the blend is the dominant factor for the reduction of CH₃OCH₃ and CO mole fractions in the flame. The rate of the primary reactions related to CH₃OCH₃ and CO increases obviously with the addition of hydrogen. When the volume fractions of H₂ to the total of DME and H₂ exceeds 40%, H₂ will change from an intermediate species to a reactant, which means the effect of H₂ on the premixed combustion will be more significant. The free radicals in the radical pool, such as H, O and OH radicals, increase as hydrogen is added, which promote the combustion process. The mole fraction of CH₂O is decreased as hydrogen is added. Less soot precursors (acetylene (C₂H₂)) were produced with the addition of H₂.     

Numerical study of the effect of hydrogen addition on methane–air mixtures combustion

The stoichiometric methane–hydrogen–air freely propagated laminar premixed flames at normal temperature and pressure were calculated by using PREMIX code of CHEMKIN II program with GRI-Mech 3.0 mechanism. The mole fraction profiles and the rate of production of the dominant reactions contributing to the major species and some selected intermediate species in the flames of methane–hydrogen–air were obtained. The rate of production analysis was conducted and the effect of hydrogen addition on the reactions of methane–air mixtures combustion was analyzed by the dominant elementary reactions for specific species. The results showed that the mole fractions of major species CH₄, CO and CO₂ were decreased while their normalized values were increased as hydrogen is added. The rate of production of the dominant reactions contributing to CH₄, CO and CO₂ shows a remarkable increase as hydrogen is added. The role of H₂ in the flame will change from an intermediate species to a reactant when hydrogen fraction in the blends exceeds 20%. The enhancement of combustion with hydrogen addition can be ascribed to the significant increase of H, O and OH in the flame as hydrogen is presented. The decrease of the mole fractions of CH₂O and CH₃CHO with hydrogen addition suggests a potential in the reduction of aldehydes emissions of methane combustion as hydrogen is added. The methane oxidation reaction pathways will move toward the lower carbon reaction pathways when hydrogen is available and this has the potential in reducing the soot formation. Chemical kinetics effect of hydrogen addition has a little influence on NO formation for methane combustion with hydrogen addition.     

Experimental and kinetic modeling study of 2,5-dimethylfuran pyrolysis at various pressures

The pyrolysis of 2,5-dimethylfuran (DMF) in a flow reactor was investigated at various pressures (30, 150 and 760 Torr) by synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Dozens of pyrolysis products, especially a series of radicals and aromatics, were identified from the measurement of photoionization efficiency spectra; and their mole fraction profiles were measured at 780–1470 K. Phenol, 1,3-cyclopentadiene, 2-methylfuran, vinylacetylene and 1,3-butadiene were observed with high concentrations in the decomposition of DMF. The pressure-dependent rate constants of the major unimolecular decomposition reactions of DMF were theoretically calculated, and was adopted in the pyrolysis model of DMF with 285 species and 1173 reactions developed in the present work. The model was validated against the species profiles measured in both the present work and the previous pyrolysis studies of DMF. Based on the rate of production and sensitivity analyses, main pathways in the decomposition of DMF and the growth of aromatics were determined. The unimolecular decomposition to produce CH₃CHCCH and acetyl radicals, H-atom abstraction to produce 5-methyl-2-furanylmethyl radical, ipso substitution by H-atom to produce 2-methylfuran and H-atom attack to produce 1,3-butadiene and acetyl radical were concluded to dominate the primary decomposition of DMF. Further decomposition of 5-methyl-2-furanylmethyl radical leads to great production of phenol and 1,3-cyclopentadiene which can be readily converted to precursors of large aromatics such as cyclopentadienyl radical, phenyl radical and benzene. As a result, the formation of aromatics in the pyrolysis of DMF is promoted compared with the pyrolysis of cyclohexane and methylcyclohexane under very close conditions. This observation implies the potentially high sooting tendency of DMF, and emphasizes the necessity to investigate the sooting behavior and soot formation mechanism in DMF combustion for the potential application of DMF as an alternative engine fuel.     

Measurements of laminar flame speeds of acetone/methane/air mixtures

The effect of acetone on the laminar flame speed of methane/air mixtures is investigated over a range of stoichiometries at atmospheric pressure and room temperature. The liquid acetone is vaporised and seeded into the methane/air mixture at 5%, 9% and 20% of the total fuel by mole. The experiment is performed using the jet-wall stagnation flame configuration and the particle imaging velocimetry (PIV) technique. Laminar flame speeds are derived by extrapolating the reference flame speed back to zero strain rate. Experimental results are compared to numerically calculated values using a base methane chemical kinetic mechanism (GRI-Mech 3.0) extended with acetone oxidation and pyrolysis reactions from the literature. The experimental results show that acetone addition does not affect the laminar flame speed of methane significantly within the range of concentrations considered, with a stronger effect on the rich range than under fuel-lean conditions, and that the peak laminar flame speed of acetone in air is ∼42.5 cm/s at ? = 1.2. Simulation results reveal that the most important reactions determining acetone laminar flame speeds are H + O₂ → O + OH, OH + CO → H + CO₂, HO₂ + CH₃ → OH + CH₃O and H + O₂ + H₂O → HO₂ + H₂O. Comparison of the expected disappearance of acetone relative to methane shows that the former is a good fluorescent marker for the latter.     

A comprehensive chemical kinetic combustion model for the four butanol isomers

Alcohols, such as butanol, are a class of molecules that have been proposed as a bio-derived alternative or blending agent for conventional petroleum derived fuels. The structural isomer in traditional “bio-butanol” fuel is 1-butanol, but newer conversion technologies produce iso-butanol and 2-butanol as fuels. Biological pathways to higher molecular weight alcohols have also been identified. In order to better understand the combustion chemistry of linear and branched alcohols, this study presents a comprehensive chemical kinetic model for all the four isomers of butanol (e.g., 1-, 2-, iso- and tert-butanol). The proposed model includes detailed high-temperature and low-temperature reaction pathways with reaction rates assigned to describe the unique oxidation features of linear and branched alcohols. Experimental validation targets for the model include low pressure premixed flat flame species profiles obtained using molecular beam mass spectrometry (MBMS), premixed laminar flame velocity, rapid compression machine and shock tube ignition delay, and jet-stirred reactor species profiles. The agreement with these various data sets spanning a wide range of temperatures and pressures is reasonably good. The validated chemical kinetic model is used to elucidate the dominant reaction pathways at the various pressures and temperatures studied. At low-temperature conditions, the reaction of 1-hydroxybutyl with O₂ was important in controlling the reactivity of the system, and for correctly predicting C₄ aldehyde profiles in low pressure premixed flames and jet-stirred reactors. Enol–keto isomerization reactions assisted by radicals and formic acid were also found to be important in converting enols to aldehydes and ketones under certain conditions. Structural features of the four different butanol isomers leading to differences in the combustion properties of each isomer are thoroughly discussed.     

Experimental study on the relationships between composition distribution and laminar flame speed of pyrolysis products

Experiments are performed to determine the effects of composition distribution on the laminar flame speeds of various pyrolysis products. The compositions of the pyrolysis gases are found to be the same, with hydrogen, methane, and ethylene comprising the majority. However, the compositions of the pyrolysis liquids are quite different under various cracking conditions. The C₁₀–C₁₂ cycloalkanes and alkanes account for the majority of the composition when the conversion rate is relatively low (≤0.072), while the C₆–C₈ aromatics and alkenes gradually become the dominant species with an increase in the conversion rate. Experimental results show that the laminar flame speeds of different pyrolysis gases (or different pyrolysis liquids) have a few discrepancies, although the pyrolysis conditions are quite different. However, the laminar flame speeds of different pyrolysis products show significant differences, which are found to be related to both the pyrolysis gas content and the properties of the pyrolysis liquids.     

Multi-species measurements in 1-butanol pyrolysis behind reflected shock waves

The kinetics of 1-butanol pyrolysis were investigated by measuring multi-species time histories using shock tube/laser absorption methods. Species time histories of OH, H₂O, C₂H₄, CO, and CH₄ were measured behind reflected shock waves using UV and IR laser absorption during the high-temperature decomposition of 1% 1-butanol/argon mixtures. Initial reflected shock temperatures and pressures for these experiments covered 1250–1650 K and 1.3–1.9 atm. Measured OH and H₂O time histories are in good agreement with previous experimental studies; measured C₂H₄, CO, and CH₄ time histories are the first reported for this fuel in shock tube experiments.Production pathways and sensitivities for the measured species are analyzed using the recent Sarathy et al. (2012) [37] detailed mechanism. Simulations using this mechanism underpredict H₂O, OH, and C₂H₄ mole fractions, overpredict CH₄ mole fractions, and significantly underpredict CO mole fractions at early times. As discussed in past papers and confirmed in this study, the branching ratios of H abstraction rates from 1-butanol, which are not precisely known, can significantly affect H₂O time history simulations. These simulations show that H₂O is produced primarily through H-atom abstraction from 1-butanol by OH, and therefore H₂O time histories are extremely sensitive to 1-butanol decomposition channels that contribute to the OH radical pool. Simulations also show that more C₂H₄ would be produced by faster decomposition of 1-butanol through several channels that also affect H₂O production. Finally, simulations show that CO time histories are strongly sensitive to 1-butanol decomposition into nC₃H₇ and CH₂OH, especially at early times. Evidence is presented that indicates this decomposition pathway is too slow in the simulations by a factor of three to five at conditions of the current study.     

Isomer-specific combustion chemistry in allene and propyne flames

A combined experimental and modeling study is performed to clarify the isomer-specific combustion chemistry in flames fueled by the C₃H₄ isomers allene and propyne. To this end, mole fraction profiles of several flame species in stoichiometric allene (propyne)/O₂/Ar flames are analyzed by means of a chemical kinetic model. The premixed flames are stabilized on a flat-flame burner under a reduced pressure of 25 Torr (=33.3 mbar). Quantitative species profiles are determined by flame-sampling molecular-beam mass spectrometry, and the isomer-specific flame compositions are unraveled by employing photoionization with tunable vacuum-ultraviolet synchrotron radiation. The temperature profiles are measured by OH laser-induced fluorescence. Experimental and modeled mole fraction profiles of selected flame species are discussed with respect to the isomer-specific combustion chemistry in both flames. The emphasis is put on main reaction pathways of fuel consumption, of allene and propyne isomerization, and of isomer-specific formation of C₆ aromatic species. The present model includes the latest theoretical rate coefficients for reactions on a C₃H₅ potential [J.A. Miller, J.P. Senosiain, S.J. Klippenstein, Y. Georgievskii, J. Phys. Chem. A 112 (2008) 9429-9438] and for the propargyl recombination reactions [Y. Georgievskii, S.J. Klippenstein, J.A. Miller, Phys. Chem. Chem. Phys. 9 (2007) 4259-4268]. Larger peak mole fractions of propargyl, allyl, and benzene are observed in the allene flame than in the propyne flame. In these flames virtually all of the benzene is formed by the propargyl recombination reaction.     

Modeling of 1,3-hexadiene, 2,4-hexadiene and 1,4-hexadiene-doped methane flames: Flame modeling, benzene and styrene formation

In this work, we have developed a detailed chemical kinetic model and reacting flow simulation for the hexadiene-doped 2-d methane diffusion flames studied experimentally by McEnally and Pfefferle. The GRI-Mech 2.11 methane oxidation and Lawrence Livermore butane oxidation mechanisms were used as the base mechanism to which hexadiene chemistry generated by Reaction Mechanism Generator (RMG) was added. Some important chemically activated pathways leading to aromatic species formation, including the reactions on C₅H₇, C₆H₁₀, C₆H₉, C₆H₇, C₈H₈ and C₈H₉ potential energy surfaces, are examined in great detail using quantum chemistry (CBS-QB3) and master equation analysis as implemented in Variflex.An efficient program to solve the doped methane diffusion flame was developed. The solver uses the method of lines to solve the species mass balance equation arising in the diffusion flame. It assumes that the temperature and velocity profiles of the doped flame are the same as those of the undoped flame.The mole fractions of various species as predicted by our model are compared to the experimentally measured mole fractions. The agreement between theory and experiments is quite good for most molecules. The added hexadiene dopants to the flame decompose to produce significant amount of cyclopentadienyl radical, which combines with methyl radical to produce benzene. We also show that styrene is formed primarily by recombination of cyclopentadienyl and propargyl radicals, a pathway which to our knowledge, has not been included in prior flame simulations.     

Comprehensive reaction mechanism for n-butanol pyrolysis and combustion

A detailed reaction mechanism for n-butanol, consisting of 263 species and 3381 reactions, has been generated using the open-source software package, Reaction Mechanism Generator (RMG). The mechanism is tested against recently published data – jet-stirred reactor mole fraction profiles, opposed-flow diffusion flame mole fraction profiles, autoignition delay times, and doped methane diffusion flame mole fraction profiles – and newly acquired n-butanol pyrolysis experiments with very encouraging results. The chemistry of butanal is also validated against autoignition delay times obtained in shock tube experiments. A flux and sensitivity analysis for each simulated dataset is discussed and reveals important reactions where more accurate rate constant estimates were required. New rate constant expressions were computed using quantum chemistry and transition state theory calculations. Furthermore, in addition to comparing the proposed model with the eight datasets, the model is also compared with recently published n-butanol models for three of the datasets. Key differences between the proposed model and the published models are discussed.     

Experimental and kinetic modeling study on methylcyclohexane pyrolysis and combustion

Methylcyclohexane is the simplest alkylated cyclohexane, and has been broadly used as the representative cycloalkane component in fuel surrogates. Understanding its combustion chemistry is crucial for developing kinetic models of larger cycloalkanes and practical fuels. In this work, the synchrotron vacuum ultraviolet photoionization mass spectrometry combined with molecular-beam sampling was used to investigate the species formed during the pyrolysis of methylcyclohexane and in premixed flame of methylcyclohexane. A number of pyrolysis and flame intermediates were identified and quantified, especially including radicals (e.g. CH₃, C₃H₃, C₃H₅ and C₅H₅) and cyclic C6- and C7-intermediates (benzene, 1,3-cyclohexadiene, cyclohexene, toluene, C₇H₁₀ and C₇H₁₂, etc.). In particular, the observation of cyclic C6- and C7-intermediates provides important experimental evidence to clarify the special formation channels of toluene and benzene which were observed with high concentrations in both pyrolysis and flame of methylcyclohexane. Furthermore, the rate constants of H-abstraction of methylcyclohexane via H attack, and the isomerization and decomposition of the formed cyclic C₇H₁₃ radicals were calculated in this work. A kinetic model of methylcyclohexane combustion with 249 species and 1570 reactions was developed including a new sub-mechanism of MCH. The rate of production and sensitivity analysis were carried out to elucidate methylcyclohexane consumption, and toluene and benzene formation under various pyrolytic and flame conditions. Furthermore, the present kinetic model was also validated by experimental data from literatures on speciation in premixed flames, ignition delays and laminar flame speeds.     

Identification of combustion intermediates in a low-pressure premixed laminar 2,5-dimethylfuran/oxygen/argon flame with tunable synchrotron photoionization

Low-pressure (4.0 kPa) premixed laminar 2,5-dimethylfuran (DMF)/oxygen/argon flame with an equivalence ratio of 2.0 was studied with tunable vacuum ultraviolet (VUV) synchrotron radiation photoionization and molecular-beam mass spectrometry. Photoionization mass spectra of DMF/O₂/Ar flame were recorded and the photoionization efficiency curves of the combustion intermediates were measured. Flame species, including isomeric intermediates, are identified by comparing the measured ionization energies with those reported in literatures or those calculated with Gaussian-3 procedure. More than 70 species have been detected, including furan and its derivatives, aromatics, and free radicals. Possible reaction pathways of DMF, 2-methylfuran, and furan are proposed based on the intermediates identified. DMF can be consumed by H-abstraction and pyrolysis reactions. 2-Methylfuran and furan can be consumed by H-abstraction, H-addition and pyrolysis reactions.