Gas production from the pyrolysis of oil shale as affected by Fe₂O₃

In this study, the effects of Fe₂O₃ on the formation of noncondensed gas and the higher heating value (HHV) of pyrolysis gas during the pyrolysis of oil shale were studied by using the horizontal tube furnace retorting test bed and Fourier infrared spectrometer. In order to exclude the impact of other mineral matter on oil shale retorting process, this research adopts washing oil shale with HCl-HF-HNO₃ to obtain LongKou oil shale organic matter. Based on the ash composition analysis of pyrite, equivalent amounts of Fe₂O₃ (0, 2.5, 8, 40%), with the same Fe content as pyrite, were directly loaded onto the organics. Research indicates that Fe₂O₃ can facilitate the decomposition of large molecules in organic matter, resulting in the production of more CO and enhancing the overall HHV of pyrolysis gas. However, excessive amounts of Fe₂O₃ can lead to the conversion of CO into CO₂ and inhibit the formation of C₂H₆, thereby reducing the HHV of pyrolysis gas. When the addition of Fe₂O₃ increases from 2.5% to 8%, the gas conversion rate rises from 37.45% to 41.94%, and the maximum HHV of pyrolysis gas also increases from 41.35 to 41.79 MJ/Nm³. Nevertheless, when the addition of Fe₂O₃ reaches 40%, the maximum HHV of pyrolysis gas drops to only 35.43 MJ/Nm³.