Upgrading Low Value Refinery Streams into Electrode Grade Petroleum Pitch

Abstract

Petroleum pitch is an excellent precursor for a number of advanced carbon materials such as carbon fibres, carbon molecular sieves, mesocarbon micro-beads, activated carbon spheres, needle coke etc. Some of the refinery streams have good potential for making pitches. These streams are the by-products of petroleum refining processes. Currently, these streams are being sold as low value ‘fuel oils.’ The present study has been carried out to examine the feasibility of making electrode grade impregnating pitches from aromatic extract of waxy distillates, a by-product of lube refining. Pitches were prepared by thermally induced polymerization and condensation of aromatic extracts obtained by solvent extraction of waxy distillates. It was found that, it is possible to produce quality-impregnating pitches from aromatic extracts. These pitches are of good quality having key properties like softening point (112–128°C), coking value (>45 wt%) and quinoline insolubles (<1 wt%), and are well comparable with Ashland's A-240 pitch which is used as impregnating pitch in graphite electrode plants world over. Average structural parameters (Har, α-Ph, β-CH2, γ-CH3 etc.) of these pitches have been computed from NMR spectra and used for comparison purpose. It appears that integration of pitch making process in refineries will improve the profitability by converting low value aromatic extracts into high priced petroleum pitches.