A temperature-programmed oxidation method for quantitative characterization of the thermal cokes morphology

A series of thermal cokes obtained by coking of vacuum residues and fractions have been studied by polarized light microscopy observation, scanning electron microscope (SEM), and temperature-programmed oxidation (TPO) technique. The anisotropic degrees of coke samples are found to be considerably different for discriminating characterization, which indicates that the coke morphology is closely dependent on the chemical nature of the coking materials. The restricted mesophase development in thermal coke might be ascribed to the increasing amount of heteroatoms contained in the parent coking materials. A proper signal analysis procedure of TPO profiles was obtained to discriminate the carbon species in the coke quantitatively, and then a good one-to-one correlation between determinations by polarized-light micrographs analysis and TPO method was observed, which shows that the TPO technique could be a suitable and more rapid method than polarized-light microscopy to quantitatively assess the morphology of coke, even in some situations in which the traditional method is inadequate.