Theoretical Studies of the Hydrogen Abstraction from Poly(oxymethylene) Dimethyl Ethers by O2 in Relation with Cetane Number Data

Poly(oxymethylene) dimethyl ethers (PODMEn, n = 2-6) are novel oxygenated compounds that can be used as promising candidates for new-generation fuels because of their excellent combustion performance. The oxidation of PODMEn (n = 2-6) is essential for the understanding of the combustion process. It is necessary to study the relationship between kinetic parameters and cetane number (N) of PODMEn (n = 2-6). In order to predict initiation step rate constants for the oxidation of PODMEn (n = 2-6), quantum mechanical calculations are performed using M06-2X/6-311G(d,p) and B3LYP/6-311G(d,p) methods. Structural, energetic, thermodynamics, and kinetics of the automatic ignition process are assessed. The kinetic model based on the conventional transition state theory is used to calculate the initiation step reaction rate constants at 1000 K. In both M06-2X/6-311G(d,p) and B3LYP/6-311G(d,p) methods, the calculated rate constants of the hydrogen abstraction process have an excellent correlation with the experimental CN of PODMEn (n = 2-6). Our methodology presented here can be used to simulate chemical kinetics for other fuel additives.