Article pubs.acs.org/EF
Experimental Study of Tetralin Oxidation and Kinetic Modeling of Its Pyrolysis and Oxidation Philippe Dagaut,† Alain Ristori,† Alessio Frassoldati,‡ Tiziano Faravelli,‡ Guillaume Dayma,† and Eliseo Ranzi*,‡ †
Centre National de la Recherche Scientifique (CNRS−INSIS), 1-C, Avenue de la recherche scientifique45071 Orléans cedex 2, France ‡ Dipartimento di Chimica, Materiali ed Ingegneria Chimica “G. Natta” Politecnico di Milano, Piazza Leonardo da Vinci 3220133 Milano, Italy S Supporting Information *
ABSTRACT: Tetralin is the simplest polycyclic naphtheno-aromatic hydrocarbon found in liquid fuels (e.g., jet fuels, diesel). It is also produced by the pyrolysis and oxidation of decalin. To get a better understanding of tetralin combustion characteristics, new oxidation experiments were performed in a jet-stirred reactor, and the results are reported here. For the first time, stable species concentration profiles were measured at 1 and 10 atm over a range of equivalence ratios (φ = 0.5−1.5) and temperatures (790−1400 K). The oxidation of tetralin under these conditions was simulated using a semidetailed kinetic reaction scheme (∼10 000 reactions and ∼400 species) deriving from a chemical kinetic model proposed earlier for the oxidation of decalin over a wide range of conditions (jet-stirred reactor, plug-flow reactor, and shock-tube). The proposed kinetic model shows reasonable agreement with the present measurements. It can also be used to represent tetralin pyrolysis based on a variety of results available in the literature. Sensitivity analyses and reaction pathway computations were used for rationalizing the results.
1. INTRODUCTION Naphtheno-aromatics are components of currently used transportation liquid fuels, i.e., jet fuels and diesel. They are also produced by dehydrogenation of decalin derivatives that can be produced from lignin processing.1 Tetralin is the simplest naphtheno-aromatic. Nevertheless, as recently discussed by Yang and Boehman,2 despite the several experimental and mechanistic studies on the gas phase and supercritical pyrolysis of tetralin,3−10 the gas-phase oxidation of pure tetralin has not been studied experimentally in great detail. Tetralin oxidation was indeed studied by Lenhert et al.,11 together with other hydrocarbons at low-temperatures (600−800 K), in a pressurized flow reactor at 8 bar, a residence time of 0.12 s, and an equivalence ratio of 0.3. Only CO formation was reported to simulate the oxidation of jet fuels. Bounaceur et al.4 developed and validated a detailed kinetic model for tetralin pyrolysis over a relatively low temperature range (600−800 K). At low temperatures, large production of 1-methylindane and n-butylbenzene complements the dehydrogenation paths toward naphthalene and dialin (1,2-dihydronaphthalene). When the temperature increases, the formation of 1-methylindane decreases, whereas those of n-butylbenzene and naphthalene increase. Poutsma3 proposed a detailed kinetic scheme (50 species in ∼200 reactions) and highlighted the major reaction paths of tetralin pyrolysis. Parallel to the dehydrogenation reactions to dialin and naphthalene, tetralin can isomerize and rearrange to methylindans and methylindenes. It can also proceed via ring-opening to yield butylbenzene, 2-allytoluene, ethylbenzene, and styrene. Li et al.9 proposed a kinetic scheme (149 species vs 554 reactions) to represent their low pressure pyrolysis data obtained in a small laminar flow reactor at 30 Torr. Yang and Boehman2 compared the © 2013 American Chemical Society
oxidation behavior of tetralin, decalin, and cycloalkanes (cyclohexane, methylcyclohexane, and methylcyclopentane) in a motored engine at low to intermediate temperatures, with a variable compression ratio (4−15). While decalin (and cycloalkanes) exhibited significant low-temperature reactivity, tetralin was scarcely reactive prior to autoignition.2 The observed product distribution from tetralin oxidation under motor conditions was for the most part similar to that from the pyrolysis of tetralin in the gas phase. The goals of this study are 2-fold: (i) getting a better understanding of the combustion behavior of tetralin through a new experimental study of the oxidation of tetralin in a jetstirred reactor; (ii) proposing a comprehensive semidetailed kinetic reaction scheme for tetralin oxidation and pyrolysis. The experimental and modeling results are presented here and are interpreted through reaction path and sensitivity analyses.
2. EXPERIMENTAL SECTION 2.1. Jet-Stirred Reactor Setup. The experimental setup used in this work has been presented previously.12,13 The spherical fused silica jet-stirred reactor (JSR) has a 4 cm diameter and is equipped with four injectors with nozzles of 1 mm i.d. Prior to the injectors, the reactants were diluted with N2 (1000 K) and moderate pressures (
