Recycling of waste lubricant oil into chemical feedstock or fuel oil over supported iron oxide catalysts

The recycling of waste lubricant oil from automobile industry was found to be best alternative to incineration. Silica (SiO2), alumina (Al2O3), silica–alumina (SiO2–Al2O3) supported iron oxide (10 wt% Fe) catalysts were prepared by wet impregnation method and used for the desulphurisation of waste lubricant oil into fuel oil. The extent of sulphur removal increases in the sequence of Fe/SiO2–Al2O3<Fe/Al2O3<Fe/SiO2 and this might be due to the presence of smaller crystalline size (7.4 nm) of Fe2O3 in Fe/SiO2 catalyst. X-ray diffraction results suggest the presence of iron sulphide in the used catalyst. Gas chromatography with thermal conductivity detector analysis confirms the presence of H2S in gaseous products. In addition, Fe/SiO2 catalyst facilitated the formation of lower hydrocarbons by cracking higher hydrocarbons (≈C40) present in waste lubricant oil.