Thermal Decomposition of 2,5-Dimethylfuran. Experimental Results and Computer Modeling

Abstract

The thermal reactions of 2,5-dimethylfuran were studied behind reflected shock waves in a pressurized driver single pulse shock tube over the temperature range 1070−1370 K and overall densities of ∼3 × 10-5 mol/cm3. A large number of products resulting from unimolecular cleavage of the ring and consecutive free radical reactions were obtained under shock heating. A methyl group migration from C(2) to C(3) in the ring with the elimination of CO produces four isomers of C5H8 in unimolecular processes. An additional unimolecular process is the decomposition of 2,5-dimethylfuran to CH3CO and C4H5 which is an important initiator of free radical reactions. Ejection of a hydrogen atom from the methyl group in the molecule is another channel for initiation of free radical reactions in the system. The 2,5-dimethylfuryl radical, which is obtained in the process of H-atom ejection, decomposes in channels similar to those of 2,5-dimethylfuran to produce, among other products, C5H7, which is the precursor of cyclopentadiene. The major decomposition product found in the post shock mixtures is carbon monoxide. The rate constant of its overall formation is estimated as k CO = 1015.81exp(−75.1 × 103/RT) s-1 where R is expressed in units of cal/(K mol). Other products that were found in the postshock samples in decreasing order of abundance were C4H4, C2H2, and CH4 in roughly the same abundance, C2H4, C2H6, CH2CH−CHCH2, cyclopentadiene p-C3H4, and a-C3H4 and 2-methylfuran. Other isomers of C4H6, C5H6 and C5H8, and some additional products were found in very small quantities. The total decomposition of 2,5-dimethylfuran in terms of a first-order rate constant is given by: k total = 1016.22exp(−77.5 × 103/RT) s-1. An oxygen−carbon mass balance among the decomposition products is obtained. A reaction scheme composed of 50 species and some 180 elementary reactions accounts for the product distribution over the temperature range covered in this study. First-order Arrhenius rate parameters for the formation of the various reaction products are given, a reaction scheme is suggested, and results of computer simulation and sensitivity analysis are shown. Differences and similarities among the reactions of furan, 2-methylfuran, and 2,5-dimethylfuran are discussed.

Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography – Part I: Furan

“…Before a potential biofuel should be used in practice, it is advisable to investigate it carefully with respect to its combustion chemistry, including information on the nature and amount of undesired and potentially harmful products. Some of the earlier experimental studies regarding furan fuels have investigated their thermal decomposition [6][7][8][9][10][11][12][13][14][15]. Only a few experiments addressed all three furanic fuels.…”

“…Only a few experiments addressed all three furanic fuels. Especially Grela et al [6] employed a heated flow reactor to determine the decomposition rates of furan, 2-methylfuran (MF), and 2,5-dimethylfuran (DMF), and analyzed the pyrolysis products using an online gas chromatography coupled to a mass spectrometer at very low pressure (1.3×10 −3 mbar) and over the temperature range of 1050-1270 K. Also, Lifshitz et al [7][8][9] used shock tube experiments to investigate the thermal decomposition of these three furanic fuels over the temperature range of about 1050 to 1460 K, at pressures of 2 atm. Measurements of the final products were also obtained using gas chromatography techniques, and a chemical kinetic mechanism was proposed to model their results.…”

“…Measurements of the final products were also obtained using gas chromatography techniques, and a chemical kinetic mechanism was proposed to model their results. Both Grela et al [6] and Lifshitz et al [7][8][9] concluded that the rate coefficients for thermal decomposition of these furanic fuels increase with increasing alkylation of the furan ring.…”

Advanced Biofuels and Beyond: Chemistry Solutions for Propulsion and Production

“…[58] Ar ecent review by Xu et al [212] presents an overview of available experimental data that may be used for model validation. After some early shock-tube studies,f or example,byLifshitz et al, [213] the first flame measurements of species concentrations were reported in 2011 for furan [172] and tetrahydrofuran. [179] Them ain body of experimental data on the combustion of fuels of the furan and tetrahydrofuran families has been published since 2013, with mechanism development and validation addressed in parallel.…”

Recent Trends in the Production, Combustion and Modeling of Furan-Based Fuels

“…A large number of experimental studies involved investigations of thermal decomposition in shock tubes and flow reactors [114,[134][135][136][137][138][139][140][141][142][143][144][145][146]. Other studies were aimed at the exploration of rate constants of furan reactions with important radicals during oxidation [20,132,144,[147][148][149][150][151][152].…”