Catalytic hydropyrolysis of El-Lajjun and Julia Creek shale oils using flow-through and sealed autoclaves

Abstract

High-sulfur shale oils from two marine oil shales, El-Lajjun (Jordan) and Julia Creek (Australia) were subjected to hydropyrolysis using NiMo catalysts deposited on Al-SBA-15 with Si/Al ratios ranging from 10 to 75, i.e. with decreasing acidity, both in a flow-through system at 0.1 MPa H2 pressure and in sealed autoclaves at varying H2 pressure (1–6 MPa (cold, i.e., at room temperature)). For autoclave pyrolysis of El-Lajjun shale oil catalysed by NiMo-Al-SBA-15 (Si:Al = 10:1), sulfur content of oil decreased with H2 pressure, catalyst:oil ratio and temperature, pyrolysis time having little effect. Coking decreased with increasing H2 pressure, but increased with increasing temperature and catalyst:oil ratio. Time had little effect on coking. The conditions finally adopted were 400 °C, 6 MPa (cold) H2 pressure, 30 min pyrolysis time and (0.1:1.0) catalyst:oil ratio. Lower Si/Al ratios (≤50) all gave the same hydrodesulphurization (HDS) activity, but coking declined with decreasing Si/Al ratio, so that the optimum ratio was 10. The Julia Creek shale oil also showed good HDS, but was more susceptible to coking at high Si/Al ratio. The oil obtained in catalysed pyrolysis contained almost no thiophenes or benzothiophenes and had more high-boiling point material than oil from non-catalysed pyrolysis. The catalyst was successfully regenerated after use and was also effective in HDS of both raw oil shales. For the flow-through experiments, no significant hydrodesulphurization (HDS) was observed for either shale oil, but some hydrodenitrogenation (HDN) occurred for the Julia Creek shale oils.