Cracking of Used Engine Oil to Gasoline-Like Fuel Using Iron Oxide Nanoparticles Supported on HZSM-5

Abstract

Every day, large amount of used engine oil (UEO) is produced, which has major environmental issues due to its hazardous contaminants.  UEO contains high percentage of higher molecular weight hydrocarbons that can be turned into valuable fuel products. Catalytic cracking  of UEO oil into gasoline-like fuel using iron oxide nanoparticles over HZSM-5 support was investigated. The Fe3O4 nanoparticles  was synthesised via the one-spot method using iron (III) chloride hexahydrate (FeCl₃.6H₂O) and iron (II) chloride  tetrahydrate (FeCl₂.4H₂O) as precursors, while the HZSM-5 was synthesized using Al2(SO4)3.18H₂O and Na₂SiO₃ as sources of alumina  and silica, respectively. The catalysts properties were investigated by XRD, FTIR, EDXRF, and TGA methods. The UEO was cracked in a fixed stainless-steel batch reactor at 400 °C for 1h with and without the catalyst. ASTM standard procedures, gas chromatography coupled with  mass spectrometry (GC-MS), and Fourier transformed infrared spectroscopy (FTIR) were used to examine the fuel properties,  molecular profile, and functional groups respectively, of the raw UEO and cracked liquid products. The results of GC-MS showed that the  10 wt.% Fe₃O₄/HZSM-5 catalyst is 86.04% selective towards C5 – C10 hydrocarbons, 63.16% selective towards olefins, and 18.42% selective  towards aromatics. The high selectivity of the catalyst towards lighter hydrocarbons could be attributed to the pore size distribution of HZSM-5, which offers active sites for catalytic cracking. The fuel properties of the liquid products obtained using catalyst  were found to be very similar to those of standard gasoline. Based on the results of the molecular profile and fuel properties, it was  concluded that Fe₃O₄/HZSM-5 is a promising catalyst for cracking UEO, and the fuel obtained could be used directly in spark-ignition  engines without any negative impact on engine performance.