Although the relation between carbon structure and reactivity is well-known from thermal and oxidative studies of coal, char and graphite, the relation for soot remains unstudied. In this article, the dependence of the soot oxidation rate upon nanostructure, namely the length, separation distance and curvature of the graphene segments is shown.
Soots possessing graphitic, fullerenic or amorphous nanostructure are used for this comparison. Surprisingly, the different soot nanostructures are readily produced by using different fuels and pyrolysis conditions. Reflecting different ratios of edge to basal plane sites or amounts of ring strain imposed by curvature, burnout rates are found to differ by nearly 500% for the soots studied here.
Using high resolution transmission electron images as input data, this paper interprets the varied oxidation rates in terms of differences in nanostructure between the soots. In addition to fringe length, the fringe analysis algorithm can also provide fringe separation distance and tortuosity. Results are shown in the form of histograms for each of these quantities. The combination of the three measurements can give a better indication of the graphitic structure within nanoscale carbons and can distinguish carbon nanostructure based upon fullerenic, graphitic and amorphous content.