Production of diesel-like fuel from spent engine oil by catalytic pyrolysis over natural magnetite

• Investigation on pyrolysis of spent lubricating oil.
• Influence of nat-magnetite on the yields of desirable light distillate fraction.
• Compositional analysis of the resultant liquid pyrolysate.
• Evaluation of fuel properties of the liquid pyrolysate in compassion with the generic diesel fuel.

The present work addresses the conversion of spent engine oil into reusable useful diesel like fuel via two stage pyrolysis. In the 1st stage pyrolysis, pre-baked clay was used as adsorbent in order to remove impurities and to get a clear distillate product. In the 2nd stage, the clear distillate fraction was further pyrolyzed using different amounts of natural magnetite (1–5 wt%). The catalyst was prepared in the laboratory, and characterized by scanning electron microscopy (SEM), energy dispersive x-ray (EDX), X-ray diffractometry (XRD), and surface area analysis. The yields of overall products, liquid, gas and solid residue as a function of catalyst concentration were investigated and 3 wt% catalyst (optimum) gave 97.09, 72.31, 24.77 and 2.91% yields, respectively. The liquid fraction obtained at the optimum catalyst concentration was further characterized by Fourier Transform Infra Red (FT-IR) and Gas Chromatrography–Mass Spectrometry (GC–MS) in order to determine its detailed composition in terms of hydrocarbon ranges, hydrocarbon group type’s distribution and individual hydrocarbons in comparison with the thermal run. The fuel properties of the derived liquid fraction were also investigated using ASTM/IP standard methods. The results showed that the natural magnetite exhibited good catalytic activity and selectivity towards formation of hydrocarbons having fuel value in conformity to the diesel fuel.