Catalytic oxidative desulfurization of Malaysian diesel utilizing palm kernel shell activated carbon supported cerium/iron oxide

Abstract

Existing technique of hydrodesulfurization (HDS) is no longer applicable in achieving Euro IV standard diesel due to the high operational cost, low efficiency and high operating temperature in hydrogen gas atmosphere. Due to these drawbacks, the utilization of the catalytic oxidative desulfurization (CODS) was introduced to complement the HDS process. In this study, the performance of activated carbon supported cerium and iron oxide catalysts were investigated using tert-butyl hydroperoxide (TBHP) as oxidizing agent and N,N-dimethylformamide (DMF) as extraction solvent. The effect of dopant ratio, calcination temperature, number of loading and desulfurization treatments were studied. The results showed that effective dopants ratio (% atomic weight) of Ce/Fe (80:20) prepared by wet impregnation method calcined at 400°C was the best catalyst in this study. Nitrogen adsorption/desorption measurement of CeO₂/Fe₂O₃ (80:20)-AC exhibited the characteristic of microporous structure with Type 1 IUPAC isotherm. The micrograph of the field emission scanning electron microscopy (FESEM) illustrated an inhomogeneous distribution of various particle sizes composed of cerium and iron oxides as been proven by energy dispersive X-ray analysis (EDX) on the surface of prepared bimetallic oxides catalyst. The deep desulfurization of Malaysian commercial diesel fuel contained 440 ppm sulfur was achieved after oxidation with two cycle extraction process with 98% total sulfur removal to produce Green Diesel contained 8.8 ppm sulfur has been measured using GC-FPD. The results obtained has proven that CeO₂/Fe₂O₃ (80:20)-AC can be used as potential catalyst for the removal of sulfur in the Malaysian diesel towards achieving the green diesel production.