Molecular Composition of the High-Boiling Components of Needle Coke Feedstocks and Mesophase Development

Mesophase development during the carbonization of needle coke feedstocks in delayed coking affects the microstructural anisotropy (or graphitizability) of the resulting coke. Previous work has employed gas chromatography/mass spectrometry (GC/MS) to study the relationships between the molecular comp...

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Bibliographic Details
Published in:Energy & fuels 2007-11, Vol.21 (6), p.3563-3572
Main Authors: Wang, Guohua, Eser, Semih
Format: Article
Language:English
Subjects:
Applied sciences
Crude oil, natural gas and petroleum products
Energy
Exact sciences and technology
Fuels
Materials
Processing of crude oil and oils from shales and tar sands. Processes. Equipment. Refinery and treatment units
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Summary:Mesophase development during the carbonization of needle coke feedstocks in delayed coking affects the microstructural anisotropy (or graphitizability) of the resulting coke. Previous work has employed gas chromatography/mass spectrometry (GC/MS) to study the relationships between the molecular composition of the fluid catalytic cracking decant oil (FCC DO) and mesophase development. In this study, the principal emphasis was placed on analyzing the non-GC amenable fraction of DO samples using a combination of analytical techniques, including high pressure liquid chromatography with photodiode array (PDA) and mass spectrometer detectors in tandem (HPLC/PDA and HPLC/MS/MS), and laser desorption mass spectrometry (LD/MS). The experimental data showed that major molecular species in DO samples consist of 3–6 ring multimethyl-substituted polyaromatic hydrocarbons (PAHs), including phenanthrenes, pyrenes, chrysenes, benzopyrenes, perylenes, and benzo[g,h,i]perylenes. Large differences were observed in the molecular composition of decant oil samples, particularly in the distribution of the methylPAH homologues and the degree of methylation on a given PAH. High-boiling PAHs (identified by LD/MS) and low-boiling PAHs (identified by GC/MS) were found to have similar distribution trends in molecular composition. The degree of mesophase development was found to depend strongly on the molecular composition of the feedstock samples. In particular, the ratio of total concentrations of pyrenes/phenanthrenes correlates with the degree of mesophase development during carbonization.
ISSN:0887-0624
1520-5029
DOI:10.1021/ef0605403