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Experimental and Detailed Kinetic Modeling Study of Cyclopentanone Oxidation in a Jet-Stirred Reactor at 1 and 10 atm Sébastien Thion, Casimir Togbé, Guillaume Dayma, Zeynep Serinyel, and Philippe Dagaut Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.6b02061 • Publication Date (Web): 04 Oct 2016 Downloaded from http://pubs.acs.org on October 18, 2016
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Energy & Fuels
Experimental and Detailed Kinetic Modeling Study of Cyclopentanone Oxidation in a Jet-Stirred Reactor at 1 and 10 atm Sébastien Thion1, Casimir Togbé1, Guillaume Dayma1,2, Zeynep Serinyel1,2, Philippe Dagaut1 1
CNRS-INSIS, 1C, Ave de la recherche scientifique – 45071 Orléans cedex 2, France
2
Université d’Orléans, 1 rue de Chartres – BP 6759 – 45067 Orléans cedex 2, France
Corresponding author:
[email protected] Phone: (+33) 238 255499
fax: (+33) 238 696004
Keywords: cyclopentanone, cyclic ketone, jet-stirred reactor, kinetic modeling Shortened running title: Cyclopentanone oxidation
Abstract Cyclopentanone oxidation was studied in a jet-stirred reactor at 1 and 10 atm and over the temperature range 730–1280 K for fuel-lean (φ = 0.5), stoichiometric and fuel-rich (φ = 2) mixtures. 16 reaction intermediates and products were identified and quantified using online Fourier Transform Infrared Spectrometry and offline Gas Chromatography. A kinetic submodel was developed, supported by theoretical calculations for the rate constants of hydrogen abstraction reactions by H atoms, OH, and CH3 radicals at the MP2/aug-cc-pVDZ level of theory. The resulting model consisting of 343 species involved in 2065 reactions was used to simulate the present experiments and showed good agreement with the data. Main oxygenated intermediates are aldehydes, and cyclopentenone was also found to be an important species for cyclopentanone oxidation. Rate of production analyses showed that cyclopentanone is mainly consumed by a sequence of reactions producing CO and the 1butene-4-yle radical. Unimolecular reactions reported in the literature were found to have a
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very low contribution to the fuel consumption in our experimental conditions. It was finally highlighted that some of the discrepancies observed between the simulation and the experiments arise from the chemistry of cyclopentenone that would need to be more detailed.
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Energy & Fuels
1. Introduction Cyclopentanone is a cyclic ketone that can be produced from furfural1 or biomass pyrolysis2. It can be used as an alternative fuel or as a basis for producing more complex fuels with higher energy density3. Very few studies are related to this compound in the literature. Pioneer works in the 50’s dealt with its photolysis or thermal decomposition4,5. Reported products for the decomposition were CO, C2H4, C2H2, H2, and 1-C4H8. More recently, Delles et al.6 studied the pyrolysis of cyclopentanone in a cylindrical flow reactor at low pressure between 805 and 854 K. The decomposition products were measured by Fourier Transform IR spectrometry and gas chromatography coupled to mass spectrometry. 4-Pentenal was identified as a product and a new reaction pathway was proposed to explain its formation. More recently, Zaras et al.7 studied the unimolecular decomposition of cyclopentanone through a quantum chemical modeling. The G3B3 composite method was used to estimate bond dissociation energies. The authors identified five possible pathways for cyclopentanone pyrolysis, confirming previous findings by Delles et al.6: two of these pathways yield cyclopentenone isomers, one produces 4-pentenal, while pathways involving concerted ring opening lead to 1-butene, CO, and ethylene. An additional route was found considering the keto-enol equilibrium. RRKM theory was used to determine rate constants between 800 and 2000 K. The fastest pathways were found to be the keto-enol equilibrium and the concerted ring opening. Finally, it was shown that primary products of cyclopentanone decomposition yield 1,3-butadiene and acetylene. Cyclopentanone low temperature reactivity was studied by Scheer et al.8 in a flow reactor coupled to a synchrotron photoionization mass spectrometer. The reaction of the primary radicals (generated by H-abstraction by Cl atoms) with O2 was investigated. It was found that the concerted elimination of HO2 yielding unsaturated cyclic ketones was the dominant reaction pathway under these conditions. The authors also investigated the potential
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energy surface of this system and concluded that the ring opening was not favored at low temperature, as compared to oxidation, and 2-cyclopentenone was an important intermediate. These results are well in line with the HCCI work by Yang et al.9 who found cyclopentanone was highly resistant to auto-ignition. One can understand from this short review that cyclopentanone received little attention so far despite its potential as a biofuel. This molecule also gives the opportunity to feed our knowledge on cyclic oxygenated compounds oxidation. Such information could be useful for further studies of more complex fuels produced from the different available chemical platforms (e.g. furfural). This paper therefore reports the first study of cyclopentanone oxidation in a jet-stirred reactor between 730 and 1280 K at 1 and 10 atm.
2. Experimental The present experiments were performed in a jet-stirred reactor that has been described in details earlier10. The reactor itself is a 4 cm diameter fused-silica sphere (38 cm3) with four nozzles of 1 mm i.d. designed to ensure a perfect stirring in the present operating conditions. Prior to the mixing point at the entrance of the injectors, the reactants were diluted with nitrogen (
