Fuel, Vol.237, 753-762, 2019
Enhancement of mesocarbon microbead (MCMB) preparation through supercritical fluid extraction and fractionation
Mesocarbon microbeads (MCMBs) are a valuable carbon material, and the production of this material highly depends on the reaction conditions and feedstock properties. In the present study, supercritical fluid extraction fractionation (SFEF) technology was used to separate coal tar pitch (CTP) into a series of fractions to enhance MCMB preparation. After SFEF separation, most of the toluene-insoluble (TI) components were concentrated into the unextracted residue. First, optimal carbonization conditions were obtained for CTP through systematic experimental evaluations. Then, the SFEF fractions were heat-treated under the optimal conditions to produce MCMBs, and the relationship between chemical composition and product quality was revealed. Compared with CTP products, MCMBs produced from extracted SFEF fractions showed better morphology, and only a bulk mesophase with poor texture was generated from the unextractable residue. Moreover, the TI fraction had a significant negative impact on MCMB production in carbonaceous mesophase development. The results indicate that supercritical fluid extraction can be used to improve the quality of produced MCMBs by removing undesirable components.