Soot

Soot is a solid, carbonaceous by product from many combustion processes. The sizes of soot particles range from submicron to hundreds of microns in diameter. This wide spectrum of particulates  is formed by growth mechanisms centered around aromatic ring template structures . Prior work by several research groups has identified the formation of the first aromatic ring i.e. benzene, as being a key step in the production of soot. Within our research group we are experimentally investigating the very early stages of soot production by examiniing how benzene and small polycyclic aromartics are formed from smaller species in a combustion environment.

The recombination of propargyl radicals, C₃H₃, has been proposed by several groups as being the major process in benzene formation. A potential surface, developed by quantum chemical methods, is shown to the right. The first stable product, I, on this surface is 1,5-hexadiyne. We have started a series of experiments to explore this surface and obtain reliable rate coefficients for various steps by studying both the recombination of propargyl radicals and the pyrolysis of 1,5-hexadiyne.

The early results from 1,5-hexadiyne are extremely encouraging and were recently presented at the 3rd Joint Meeting of the US Sections of the combustion institute. The extended abstract may be viewed here.

Sources :

     Melius et al., Proc. Comb. Inst.,

     1992, 24, 621-628

     Miller, J. A.; Klippenstein S. J. J. Phys. Chem. A  

     2001, 105, 7254-7266