High-temperature pyrolysis of dimethyl ether in shock waves

Abstract

The high-temperature pyrolysis of dimethyl ether (DME) was studied behind reflected shock waves using single-pulse (reaction time between 1.3 and 2.9 ms), time-resolved IR absorption (3.39 μm), IR emission (4.24 μm), and UV absorption (216 nm) methods. The studies were done using DME-Ar, DME-H 2-Ar, DME-CO-Ar, and DME-CH 2O-Ar mixtures in the temperature range 900–1900 K at pressures in the range 0.83–2.9 atm. From a computer simulation, a 94-reaction mechanism that could explain all our data was constructed. The rate constant expressions of the following five reactions at high temperatures are discussed in detail: CH 3OCH 3 + M → CH 3O + CH 3 + M, H + CH 3OCH 3 → CH 3OCH 2 + H 2, CH 3 + CH 3OCH 3 → CH 3OCH 2 + CH 4, CH 3O + CO → CH 3 + CO 2, CH 2O + CH 3 → CHO + CH 4. We found that in the pyrolysis of DME there is an extremely low tendency to form higher hydrocarbons at high temperatures.