POLYCYCLIC AROMATIC-COMPOUNDS IN OILS DERIVED FROM THE FLUIDIZED-BED PYROLYSIS OF OIL-SHALE

Oil shale was pyrolysed in a 10 cm diameter x 100 cm high fluidised bed reactor with nitrogen as the fluidising gas at pyrolysis temperatures of 400, 450, 520, 570 and 620 degrees C. The gases were analysed by packed column gas chromatography. The condensed pyrolytic oils were analysed for their content of polycyclic aromatic compounds (PAC), including polycyclic aromatic hydrocarbons (PAH), sulphur-PAH (PASH) and nitrogen-PAH (PANH). The oils were fractionated into chemical classes using mini-column liquid chromatography followed by analysis using capillary column gas chromatography with flame ionisation detection (GC/FID) and capillary column GC with mass spectrometry (GC/MS) for identification and quantification of PAH. PASH and PANH were identified in the chemical class fractions using capillary column GC with selective detection and GC/MS. The pyrolytic shale oils were found to contain significant concentrations of PAH, PASH and PANH. The concentrations of PAC were increased with increasing reactor temperature and residence time. The PAH consisted mainly of naphthalene, fluorene and phenanthrene and their alkylated homologues, and lower concentrations of fluoranthene, pyrene and chrysene. The PASH identified included benzothiophene, and dibenzothiophene, and the PANH identified including indole and carbazole and their alkylated derivatives. Some of the PAC identified have been reported to be mutagenic and/or carcinogenic.