Competing Channels in the Propene + OH Reaction: Experiment and Validated Modeling over a Broad Temperature and Pressure Range

Abstract

Abstract Although the propene + OH reaction has been in the center of interest of numerous experimental and theoretical studies, rate coefficients have never been determined experimentally between ∼600 and ∼750 K, where the reaction is governed by the complex interaction of addition, back-dissociation and abstraction. In this work OH time-profiles are measured in two independent laboratories over a wide temperature region (200–950 K) and are analyzed incorporating recent theoretical results. The datasets are consistent both with each other and with the calculated rate coefficients. We present a simplified set of reactions validated over a broad temperature and pressure range, that can be used in smaller combustion models for propene + OH. In addition, the experimentally observed kinetic isotope effect for the abstraction is rationalized using ab initio calculations and variational transition-state theory. We recommend the following approximate description of the OH + C3H6 reaction C3H6 + OH ⇆ C3H6OH (R1a,R-1a) C3H6 + OH → C3H5 + H2O (R1b) k 1a (200 K ≤ T ≤ 950 K; 1 bar ≤ P) = 1.45 × 10-11 (T/K)-0.18 e 460 K/T cm3 molecule-1 s-1 k -1a (200 K ≤ T ≤ 950 K; 1 bar ≤ P) = 5.74 × 1012 e -12690 K/T s-1 k 1b (200 K ≤ T ≤ 950 K) = 1.63 × 10-18 (T/K)2.36 e -725 K/T cm3 molecule-1 s-1