Soot Formation from the Combustion of Biomass Pyrolysis Products and a Hydrocarbon Fuel, n-Decane: An Aerosol Time Of Flight Mass Spectrometer (ATOFMS) Study

Abstract

This paper is concerned with an aerosol time-of-flight mass spectrometer (ATOFMS) study of soot formation from the combustion of proxies of biomass (eugenol, furfural) and a hydrocarbon fuel (n-decane). The objective of this work was to gain insight into the soot growth mechanism in the combustion of biomass by studying the combustion of single components of wood (eugenol–lignin model and furfural–cellulose model), and by comparison with soot composition from combustion of a hydrocarbon fuel whose soot-forming mechanism is better known. Liquid fuels were burned using a wick burner, and the products in the aerosol phase were examined using an ATOFMS. The reaction process for n-decane combustion was examined using an opposed flame simulation with Chemkin-Pro modeling. A comparison of the model output with experimental results for n-decane give information on the soot growth mechanism. The same main routes for soot formation were operative both in biomass proxies and in n-decane. The principal differences in the mechanism observed for eugenol and furfural versus n-decane are described. Mass spectral analysis indicated that a channel involving the propargyl radical is more important in furfural combustion than for the rest of the fuels. Eugenol mass spectrometry (MS) indicates the presence of the important HACA (hydrogen abstraction acetylene addition) route, producing large polycyclic aromatic hydrocarbons (PAHs). Moreover, this study gives evidence that not only lignin components contribute to soot formation in biomass combustion, but furfural, which is a cellulosic component, can also contribute, and the soot formation routes involved are different.