From electronic structure to combustion model application for acrolein chemistry part I: Acrolein + H reactions and related chemistry

Abstract

Detailed reaction kinetics of acrolein + H and related chemistry and its influence on the ignition delay time prediction of acrolein has been studied theoretically in this work. The geometry optimization and vibrational frequency calculations for every stationary point were performed at the BH&HLYP/6–311++G(d,p) level of theory, with one-dimensional hindered rotation treatments applied for low-frequency torsional modes determined by using BH&HLYP/6–31G(d). Electronic energies for all species were calculated at the ROCCSD(T)/cc-pVQ,TZ levels of theory. The kinetics and thermochemistry data were calculated and compared with existing literature results, where good agreement was observed. The branching ratios of the crucial products vary in the pressure range of 0.01–100 atm and temperatures from 298 to 2000 K. Taking 1 atm as an example, at temperatures above 1000 K, the main addition reaction products of acrolein + H are ethylene + formyl radical, while at lower temperatures, the formation of the resonantly stabilized radical, CH3ĊHCHO, is important. The dominant H-atom abstraction reaction channel by H atom proceeds at the α carbon atom of the aldehyde group of acrolein. However, the H-atom abstraction reactions are overwhelmed by the addition reactions. Decomposition reactions of four C3H3O radicals were calculated and analysed. Temperature-dependent thermochemical properties for all species in the reaction system and the pressure-dependent rate constants for each reaction pathway were incorporated into two acrolein combustion kinetic mechanisms, as well as two widely used mechanisms, AramcoMech 3.0 and JetSurF 2.0, to test the influence of the newly calculated data on acrolein oxidation. Some critical reactions for acrolein oxidation were highlighted by performing sensitivity and flux analyses.