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 + C 3 H 6 reaction C 3 H 6 + OH ⇆ C 3 H 6 OH (R1a,R-1a) C 3 H 6 + OH → C 3 H 5 + H 2 O (R1b) k 1 a (200 K ≤ T ≤ 950 K; 1 bar ≤ P ) = 1.45 × 10 -11 ( T /K) -0.18 e 460 K/ T cm 3 molecule -1 s -1 k -1 a (200 K ≤ T ≤ 950 K; 1 bar ≤ P ) = 5.74 × 10 12 e -12690 K/ T s -1 k 1 b (200 K ≤ T ≤ 950 K) = 1.63 × 10 -18 ( T /K) 2.36 e -725 K/ T cm 3 molecule -1 s -1