PUB - Publikationen an der Universität Bielefeld

The oxidation of 1-butene and i-butene with and without addition of 10 0 0 ppm NO was experimentally and numerically studied primarily at fuel-rich (phi = 2.0) conditions under high dilution (96% Ar) in a flow reactor operated at atmospheric pressure in the low temperature range of approximately 600-1200 K. Numerous intermediate species were detected and quantified using synchrotron vacuum ultraviolet pho-toionization mass spectrometry (SVUV-PIMS). An elementary-step reaction mechanism consisting of 3996 reactions among 682 species, based on literature and this work, was established to describe the reactions and interaction kinetics of the butene isomers with oxygen and nitrogenous components. Model predic-tions were compared with the experimental results to gain insight into the low-and high-temperature fuel consumption without and with NO addition and thus the respective interaction chemistry. This in-vestigation firstly contributes a consistent set of temperature-dependent concentration profiles for these two butene isomers under conditions relevant for engine exhaust gases. Secondly, the observed oxidation kinetics is significantly altered with the addition of NO. Specifically, NO promotes fuel consumption and introduces for i-butene a low-temperature behavior featuring a negative temperature coefficient (NTC) region. The present model shows reasonable agreement with the experimental results for major products and intermediate species, and it is capable to explain the promoting effect of NO that is initiated by its contribution to the radical pool. Further, it can describe the observed NTC region for the i-butene/NO mixture as a result of the competition of chain propagation and chain terminating reactions that were identified by reaction flow and sensitivity analyses. (C) 2021 The Authors. Published by Elsevier Inc. on behalf of The Combustion Institute.