Thermal decomposition reaction and a comprehensive kinetic model of dimethyl ether

Abstract

The unimolecular decomposition reaction of dimethyl ether (DME) was studied theoretically using RRKM/master equation calculations. The calculated decomposition rate is significantly different from that utilized in prior work (Fischer et al., Int J Chem Kinet 2000, 32, 713–740; Curran et al., Int J Chem Kinet 2000, 32, 741–759). DME pyrolysis experiments were performed at 980 K in a variable-pressure flow reactor at a pressure of 10 atm, a considerably higher pressure than previous validation data. Both unimolecular decomposition and radical abstraction are significant in describing DME pyrolysis, and hierarchical methodology was applied to produce a comprehensive high-temperature model for pyrolysis and oxidation that includes the new decomposition parameters and more recent small molecule/radical kinetic and thermochemical data. The high-temperature model shows improved agreement against the new pyrolysis data and the wide range of high-temperature oxidation data modeled in prior work, as well as new low-pressure burner-stabilized species profiles (Cool et al., Proc Combust Inst 2007, 31, 285–294) and laminar flame data for DME/methane mixtures (Chen et al., Proc Combust Inst 2007, 31, 1215–1222). The high-temperature model was combined with low-temperature oxidation chemistry (adopted from Fischer et al., Int J Chem Kinet 2000, 32, 713–740), with some modifications to several important reactions. The revised construct shows good agreement against high- as well as low-temperature flow reactor and jet-stirred reactor data, shock tube ignition delays, and laminar flame species as well as flame speed measurements. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 40: 1–18, 2008