Catalytic oxidative desulfurization of diesel fuel utilizing monometallic, bimetallic and trimetallic oxides doped on molybdena supported alumina

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Existing technique of hydrodesulfurization (HDS) is no longer applicable in achieving Euro IV standard diesel due to the high operational cost, low efficiency and high operating temperature in hydrogen gas atmosphere.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 the activated carbon supported cerium and iron catalysts were investigated using tertbutyl hydroperoxide (TBHP) as an oxidizing agent and N,N-dimethylformamide (DMF) extraction solvent. The effect of dopant ratio, calcination temperature, number of loading and CODS treatments were studied. The results showed that effective dopant ratio of Ce/Fe (80:20) prepared by wet impregnation method calcined at 400°C was the best catalyst. X-ray diffraction analysis (XRD) results showed that the catalyst is amorphous, while 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 catalyst. Nitrogen adsorption/desorption measurement showed the characteristic of microporous structure with Type 1 IUPAC isotherm. 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.