The reaction kinetics of dimethyl ether. I: High-temperature pyrolysis andoxidation in flow reactors

Dimethyl ether reaction kinetics at high temperature were studied in two di fferent flow reactors under highly dilute conditions. Pyrolysis of dimethyl ether was studied in a variable-pressure now reactor at 2.5 atm and 1118 K . Studies were also conducted in an atmospheric pressure flow reactor at ab out 1085 K. These experiments included trace-oxygen-assisted pyrolysis, as well as full oxidation experiments, with the equivalence ratio (phi) varyin g From 0.32 less than or equal to phi less than or equal to 3.4. On-line, c ontinuous, extractive sampling in conjunction with Fourier Transform infra- Red, Non-Dispersive Infra-Red (for CO and CO2) and electrochemical (for O-2 ) analyses were performed to quantify species at specific locations along t he axis of the turbulent flow reactors. Species concentrations were correla ted against residence time in the reactor and species evolution profiles we re compared to the predictions of a previously published detailed kinetic m echanism. Some changes were made to the model in order to improve agreement with the present experimental data. However, the revised model continues t o reproduce previously reported high-temperature jet-stirred reactor and sh ock tube results. (C) 2000 John Wiley & Sons, Inc.