Rich methane laminar flames doped with light unsaturated hydrocarbons. Part II: 1,3butadiene

TL;DR

This study investigates the structure and chemical pathways of a rich methane flame doped with 1,3-butadiene, identifying key species and reaction mechanisms, including aromatic formation pathways, through experimental and modeling approaches.

Contribution

It provides new detailed insights into the combustion chemistry of 1,3-butadiene in methane flames and improves reaction mechanisms for C3-C4 unsaturated hydrocarbons.

Findings

Identification of key combustion products including aromatic compounds.

Revealed the dominant C4 pathway to benzene formation.

Enhanced reaction mechanism for C3-C4 hydrocarbon combustion.

Abstract

In line with the study presented in the part I of this paper, the structure of a laminar rich premixed methane flame doped with 1,3-butadiene has been investigated. The flame contains 20.7% (molar) of methane, 31.4% of oxygen and 3.3% of 1,3-butadiene, corresponding to an equivalence ratio of 1.8, and a ratio C4H6 / CH4 of 16 %. The flame has been stabilized on a burner at a pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner of 36 cm/s at 333 K. The temperature ranged from 600 K close to the burner up to 2150 K. Quantified species included usual methane C0-C2 combustion products and 1,3-butadiene, but also propyne, allene, propene, propane, 1,2-butadiene, butynes, vinylacetylene, diacetylene, 1,3-pentadiene, 2-methyl-1,3-butadiene (isoprene), 1-pentene, 3-methyl-1-butene, benzene and toluene. In order to model these new results, some improvements have been made to a mechanism previously developed in our laboratory for the reactions of C3-C4 unsaturated hydrocarbons. The main reaction pathways of consumption of 1,3-butadiene and of formation of C6 aromatic species have been derived from flow rate analyses. In this case, the C4 route to benzene formation plays an important role in comparison to the C3 pathway.