Understanding the reaction pathways in premixed flames fueled by blends of 1,3-butadiene and n-butanol

The oxidation of 1,3-butadiene/n-butanol flames was studied in a combined experimental and modeling work. The goal is to provide a detailed combustion chemistry model that allows for identification of the important pathways for butadiene and butanol oxidation as well as the formation of soot precursors and aromatics. Therefore, the chemical composition has been investigated for three low-pressure (20-30 Torr) premixed flames, with different shares of butanol ranging between 25% and 75% compared to butadiene in 50% argon. Mole fraction profiles of reactants, products, and intermediates including C3Hx and C4Hx radicals as well as mono-aromatics such as benzyl radicals, were measured quantitatively as a function of height above burner surface employing flame-sampled molecular-beam mass spectrometry (MBMS) utilizing photoionization with tunable vacuum-ultraviolet synchrotron radiation. The comparison of measured species profiles with modeling results provides a comprehensive view of the reaction model's quality and predictive capability with respect to the combustion chemistry of 1,3-butadiene and n-butanol under the current low-pressure, high-temperature conditions. In general, a good agreement was found between experimental and modeled results. Reaction flux and sensitivity analysis were used to get more insights into the combustion of the fuels.