Low temperature retorting of Jordanian oil shales using semi-continuous apparatus

Abstract

Two oil shales from Jordan, El-Lajjun (EL) in the centre of the country and Isfir Al-Mahata (IA) in the south, have been analysed by elemental analysis, XRF, XRD, FTIR, TGA and 13C NMR. Both oil shales have high S contents and atomic H/C ratios. The calorific value of EL (1630 ± 10 kcal/kg) was similar to that of IA (1571 ± 13 kcal/kg). IA has higher moisture content (7.1 ± 0.3 wt% db) than EL shale (0.7 ± 0.2 wt% db); higher CaCO3 content (XRF, XRD) and lower P content (XRF, XRD). FTIR and 13C NMR indicated a high content of aliphatics for both oil shales, especially for IA shale. These oil shales have been pyrolysed at 300 °C and 320 °C for 7, 14 and 21 days under a constant flow rate of N2. The lower-temperature, long-time reaction yields and analyses of the products were compared with those obtained from the standard Fischer Assay method (520 °C for 90 min). EL oil shale was less reactive than IA oil shale, particularly at lower reaction time. For both oil shales, as the reaction time increased from 7 to 21 days, the oil yield increased to 83–90 wt% of the Fischer Assay oil yield.Fischer assay and lower-temperature, long-time reaction products were analysed using gas chromatography-mass spectrometry (GC–MS) and 1H NMR. The GC–MS results for both shales showed that all the reaction products were similar and of high aliphatic content. Higher diesel fraction was obtained for 21 day reactions at 320 °C. Homologous series of sulfur-containing organic compounds (thiophenes and benzothiophenes) were present in considerable amounts in both EL and IA reaction products. The 1H NMR measurements suggested that the Fischer assay and long-time, lower-temperature reaction products all had high aliphatic content, matching the results obtained from GC–MS measurements.