Analysis of Recovered Solvents from Coal Liquefaction in a Flowing-Solvent Reactor by SEC and UV-Fluorescence

Point of Ayr coal has been extracted using three solvents: tetralin, quinoline and 1-methyl-2-pyrrolidinone (NMP); at two temperatures: 350°C and 450°C, corresponding approximately to before and after the onset of massive covalent bond scission by pyrolysis. These solvents differ in solvent power and the ability to donate hydrogen atoms to stabilize free radicals produced by pyrolysis of the coal. Analysis of the fresh solvents and recovered solvents from coal liquefaction was achieved by size exclusion chromatography and UV-fluorescence spectroscopy. In the blank run, it was testified that the filling material sand and the steel powder did not react with solvent with increasing reaction temperature. The role of hydrogen donation in the tetralin extracts was to increase the proportion of large molecules with increasing extraction temperature. Quinoline and NMP both have the powerful extracting capability to get more materials out of coal with increasing extraction temperature.