Dissociation of dimethyl ether at high temperatures

The decomposition of dimethyl ether (CH3OCH3) has been investigated behind incident shock waves in a diaphragmless shock tube using laser schlieren densitometry, LS (T = 1500–2450 K, P = 57 ± 4, 125 ± 5 and 253 ± 12 Torr). The LS density gradient profiles were simulated and excellent agreement was found between the simulations and experimental profiles. Rate coefficients for CH3OCH3 → CH3O + CH3 were obtained. They showed strong fall-off, and at the lower end of the experimental temperature range are close to the low pressure limit. First order rate coefficient expressions were determined over 1500 < T < 2450 K. k57Torr = (3.10 ± 1.0) × 1079T−19.03 exp(−54417/T) s−1, k125Torr = (1.12 ± 0.3) × 1083T−19.94 exp(−55554/T) s−1and k253Torr = (1.02 ± 0.3) × 1073T−17.09 exp(−51500/T) s−1. The effect of a roaming channel for decomposition of dimethyl ether was assessed and the best agreement was obtained with 1% dissociation of DME via the roaming path.