Experimental and Modeling Investigation of the Low-Temperature Oxidation of Dimethyl Ether

Anne Rodriguez (1) , Ophélie Frottier (1) , Olivier Herbinet (1) , René Fournet (1) , Roda Bounaceur (1) , Christa Fittschen (2) , Frédérique Battin-Leclerc (1)

1 LRGP - Laboratoire Réactions et Génie des Procédés
2 PC2A - Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522

The oxidation of dimethylether (DME) was studied using a jet-stirred reactor over a wide range of conditions: temperatures from 500 to 1100 K, equivalence ratios of 0.25, 1 and 2, residence time of 2 s, pressure of 106.7 kPa (close to the atmospheric pressure) and an inlet fuel mole fraction of 0.02 (with high dilution in helium). Reaction products were quantified using two analysis methods: gas chromatography and continuous wave cavity ring down spectroscopy (cw-CRDS). cw-CRDS enabled the quantification of formaldehyde which is one of the major product from DME oxidation as well as that of hydrogen peroxide which is an important branching agent in low-temperature oxidation chemistry. Experimental data were compared with data computed using models from the literature with important deviations being observed for the reactivity at low-temperature. A new detailed kinetic model for the oxidation of DME was developed in this study. Kinetic parameters used in this model were taken from literature or calculated in the present work using quantum calculations. This new model enables a better prediction of the reactivity in the low-temperature region. Under the present JSR conditions, error bar on predictions were given. Simulations were also successfully compared with experimental flow reactor, jet-stirred reactor, shock tube, rapid compression machine and flame data from literature. The kinetic analysis of the model enabled to highlight some specificities of the oxidation chemistry of DME: 1) the early reactivity which is observed at very low-temperature (e.g., compared to propane) is explained by the absence of inhibiting reaction of the radical directly obtained from the fuel (by H-atom abstraction) with oxygen yielding an olefin + HO2●; 2) the low-temperature reactivity is driven by the relative importance of the second addition to O2 (promoting the reactivity through branching chain) and the competitive decomposition reactions with an inhibiting effect.

Mots clés: dimethylether; oxidation; jet-stirred reactor; modeling; quantum calculation; cw-CRDS

Domaines: Chimie théorique et/ou physique

Anne Rodriguez, Ophélie Frottier, Olivier Herbinet, René Fournet, Roda Bounaceur, et al.. Experimental and Modeling Investigation of the Low-Temperature Oxidation of Dimethyl Ether. Journal of Physical Chemistry A, 2015, 119, pp.7905-7923. ⟨10.1021/acs.jpca.5b01939⟩. ⟨hal-01178238⟩