Quantitative Analysis of Coal-Derived Liquids Residues by TLC with Flame Ionization Detection

Abstract

A reliable method for the determination of maltenes, asphaltenes, pre-asphaltenes (MAP), and tetrahydrofuran (THF) insolubles in coal liquifaction distillation residues is needed to establish the degree of coal conversion during the development of coal liquifaction processes. In this work a method for the determination of MAP, involving thin layer chromatography (TLC) and quantitative flame ionization detection (FID), is described. The THF insolubles content is calculated by difference. This method is applicable to bitumen, heavy oils, and coal-derived liquid distillation residues. The maltenes are separated from the asphaltenes and pre-asphaltenes on a TLC silica gel “chromarod” using n-pentane:isopropanol (95:5) developing solvent. The asphaltenes are then separated from the pre-asphaltenes with benzene:isopropanol (80:20) developing solvent. Results are compared with the sequential solvent extraction procedure.