Experimental investigation of the formation of polyaromatic hydrocarbons and soot during pyrolysis of ethylene with additives of dimethyl, diethyl ether, and dimethoxymethane

This paper presents the results of studies of the formation of polyaromatic hydrocarbons (PAHs) and carbon nanoparticles during pyrolysis of mixtures of ethylene with additives of linear ethers: dimethyl ether $\mathrm{CH}_3\mathrm{OCH}_3$ (DME), diethyl ether $\mathrm{C}_2\mathrm{H}_5\mathrm{OC}_2\mathrm{H}_5$ (DEE) and dimethoxymethane $\mathrm{CH}_3\mathrm{OCH}_2\mathrm{OCH}_3$ (DMM). The studies were carried out behind reflected shock waves at temperatures of $1650$–$2550$ K and pressures of $2.7$–$4.1$ atm using optical diagnostic methods: laser-induced fluorescence (LIF) and laser extinction. These additives were found to accelerate the formation of PAHs and carbon nanoparticles. Kinetic modeling results show that this effect is due to the presence of methyl and ethyl groups in the molecules, which promote the formation of PAHs and soot.