Soot Growth Mechanisms from Polyynes

Formation of soot, produced by incomplete combustion process, has attracted the attention of many environmental experts. Increasing attention has been directed to this topic because of human health concerns. Many reports, both experimental and theoretical, have been devoted to understanding the principle of soot formation. Until now, there are two major patterns of soot formation in the combustion process. The first and probably most famous is by the aggregation of polyaromatic hydrocarbons (PAHs). This pathway is also known as "growing PAHs" scheme, in which the precursors (e. g. acetylene or small hydrocarbons radical) react and form cyclic molecules such as benzene (C6H6), naphthalene, or coronene. Another method of soot formation is via polyyne molecules (C2nH2). This scheme is rarely addressed, although polyynes have been detected in high concentrations during the combustion. Polyynes, due to their reactivity, could be one of the suspected species that plays important role in the formation of soot. In this study, we discuss the current research and models related to the development of polyyne as one of the building blocks for the growth of soot.