Automated Reaction Mechanism Generation Including Nitrogen as a Heteroatom

Abstract

The open source rate-based Reaction Mechanism Generator (RMG) software and its thermochemical and kinetics databases were extended to include nitrogen as a heteroatom. Specific changes to RMG and the mining of thermochemistry and reaction kinetics data are discussed. This new version of RMG has been tested by generating a detailed pyrolysis and oxidation model for ethylamine (EA, CH3CH2NH2) at ∼1400 K and ∼2 bar, and comparing it to recent shock tube studies. Validation of the reaction network with recent experimental data showed that the generated model successfully reproduced the observed species as well as ignition delay measurements. During pyrolysis, EA initially decomposes via a CC bond scission, and the CH2NH2 product subsequently produces the first H radicals in this system via β-scission. As the concentration of H increases, the major EA consuming reaction becomes H abstraction at the α-site by H radicals, leading to a chain reaction since its product generates more H radicals. During oxidation, the dominant N2-producing route is mediated by NO and N2O. The observables were found to be relatively sensitive to the CC and CN EA bond scission reactions as well as to the thermodynamic values of EA; thermodynamic data for EA were computed at the CBS-QB3 level and reported herein. This work demonstrates the ability of RMG to construct adequate kinetic models for nitrogenous species and discusses the pyrolysis and oxidation mechanisms of EA.