Pyrolysis of dimethoxymethane and the reaction of dimethoxymethane with H atoms: A shock-tube/ARAS/TOF-MS and modeling study

Dimethoxymethane (CH3OCH2OCH3, DMM) is the smallest oxymethylene ether and currently discussed as a promising alternative diesel fuel. For an adequate modeling of the DMM combustion chemistry, reliable kinetic parameters are needed. In the present work, shock-tube studies are presented on the kinetics of the DMM + H reaction (R1) and the kinetics of the unimolecular decomposition of DMM (R2). In the case of reaction (R1), ethyl iodide pyrolysis was used as H-atom source. For both reactions, rate coefficients were determined from H-atom concentration-time profiles monitored with atom resonance absorption spectroscopy (ARAS). The following overall rate coefficients were obtained: k1(T) = (1.5 ± 0.7) × 1013 exp(− 1040 K/T) cm3 mol−1 s−1 (T = 850 − 1100 K, p ∼ 1.1 bar, bath gas: Ar) and k2(T) = (6.2 ± 1.9) × 1013 exp(− 31830 K/T) s−1 (T = 1100 − 1550 K, p ∼ 1.1 bar, bath gas: Ar). Additionally, the pyrolysis of DMM was investigated in shock-tube experiments with high-repetition time-of-flight mass-spectrometric (TOF-MS) detection (T = 1100 − 1700 K, p = 0.9 − 1.3 bar, bath gas: Ne). Concentration-time profiles of DMM, CO, CH2O, C2H6, C2H4, and CH4 were recorded simultaneously. Both the ARAS and the TOF-MS profiles can be reproduced with reasonable accuracy by simulation with a recent DMM oxidation mechanism from the literature. Mechanistic aspects are elucidated and possible modifications are proposed and discussed.