Solvent extracting coal gasification tar residue and the extracts characterization

With the technology development and application of from coal to methane, more and more fixed-bed coal gasifiers are built up in China, bringing about much coal gasification tar residue, difficult to handle. A kind of coal gasification tar residue fetched from Lurgi gasifier was extracted with ethyl acetate. Effects of ethyl acetate quantity, stirring time, extraction temperature and extraction times were investigated in this paper. Results showed the optimum conditions were as follows: ratio of ethyl acetate volume to coal gasification tar residue mass was 2 mL/g, extraction time 30 min and extraction 3 times at room temperature of 18-25 °C. About 30.58% coal gasification tar residue was extracted. The extract and residue were analyzed by GC/MS, FTIR and DSC-TGA, respectively. Results revealed that coal gasification tar residue contained polycyclic aromatic compounds, which could be extracted easily by ethyl acetate. Boiling points of the extractable polycyclic aromatic compounds were between 150 °C and 400 °C, and 95% of the polycyclic aromatic compounds were 2-4 aromatic rings, which offered valuable chemical materials for further utilization.