Formation mechanisms of selected isotropic petroleum cokes

Differences in the initial coke-structure formations were observed for several selected coker feedstocks. These variations were studied principally via polarized-light microscopic examinations of partially carbonized portions of the coker feedstocks. The first evidence of formation of a structure was exhibited by submicron units of “mesophase” formed in feedstocks on heating to temperatures around 400°C. Quantitative comparisons were made in regard to these precursory structures. Their concentrations, growth rates and coalescing behaviors were compared for a variety of petroleum coker feedstocks. The effects of heating rate, temperature and other variable carbonizing conditions on final coke structures were investigated.