Molecular modeling of the early stage of carbonization of primary heavy aromatic compounds in decant oil and its derivatives

The carbonization of decant oil and its derivatives, such as hydrotreated decant oil, coker charge, and a high-boiling point fraction, product significantly different needle coke textures. Phenanthrene, pyrene, chrysene, benzopyrene, and benzo[ghi]perylene were selected as monomers to model the initial stage of free radical formation and polymerization using a semi-empirical software package to elucidate the important initial steps in liquid-phase carbonization of the industrial needle coke feedstocks. For unsubstituted parent PAH, the initiation of free radical comes from various mechanisms such as molecular disproportionation, and hydrogen abstraction. But in the liquid phase carbonization of mostly alkylated PAH mixtures, the most probable means of initiation would be a side chain cleavage on the aromatic ring system. This is an abstract of a paper presented at the ACS Fuel Chemistry Meeting (Washington, DC Fall 2005).