Correlation of Temperature-Programmed Oxidation with Microscopy for Quantitative Morphological Characterization of Thermal Cokes Produced from Pilot and Commercial Delayed Cokers

Abstract

A wide series of thermal cokes obtained from commercial delayed cokers and a pilot coking plant have been investigated by polarized light microscopy observation, scanning electron microscopy (SEM), and temperature-programmed oxidation (TPO) technology. For discrimination of the characterization of the coke samples, the anisotropy degrees of the cokes are found to be considerably different. According to the series of runs in the pilot plant, the restricted mesophase development in thermal cokes could be ascribed to the increasing severity of coking conditions. A previous proposed signal analysis procedure was then applied to the TPO profiles of the cokes to quantitatively acquire parameters for further correlation. A fairly good linear dependency of optical texture index (OTI) upon the proportion of anisotropic carbon species from TPO (correlation coefficient of 0.984) was observed. All of the results obtained in this and our previous (A temperature-programmed oxidation method for quantitative characterization of the thermal cokes morphologyChenK.XueZ.LiuH.GuoA.WangZ. Chen, K. Xue, Z. Liu, H. Guo, A. Wang, Z. Fuel2013113274279) studies fall within a 95% confidence interval when the dependence of OTI upon the proportion from TPO is considered, therefore clearly demonstrating the validity and adaptability on the convenient determination of the proportion of anisotropic carbon species from TPO for the coke samples ranging from laboratory sources to pilot and even commercial origins. The distribution map of cokes established in this study could be used for quantitatively characterizing the morphology of various thermal cokes.