Diesel Fuel Improvement Through Photocatalytic Desulphurization Process Induced by Different Radiation Sources

Abstract

The heterogeneous photocatalytic desulfurization processes have been paid wide attention due to their effectiveness in removing the condensed organo-sulfur compounds. Such processes may gain greater consideration via utilizing the UV- visible irradiation in general and sunlight spectrum in particular. This study aimed to produce low sulfur diesel fuel through a catalyzed photochemical route using nanoparticles (NPS) of CdO, ZnO and TiO2 under different radiation sources. Both CdO and ZnO were prepared by the chemical precipitation and auto-ignition techniques while TiO2 was prepared by the chemical precipitation method only but from two different precursors. The structural and morphological characteristics of the obtained metal oxides were confirmed and determined via the different tools of analyses. According to the executed optical measurements, the CdO which was prepared by the precipitation method has shown the highest reactivity under the visible light irradiation. The production of a low sulfur diesel fuel under visible light and by using the CdO was then investigated at various operating parameters. Specifically, type of visible light source, catalyst- to- feed ratio and the reaction time. The effect of adding oxidizing agents at different ratios on the desulfurization process was also studied. The optimum conditions were obtained via the determination of the maximum sulfur removal; after testing the all parameters. These conditions were then applied to the rest of the prepared structures under both visible and UV (254 nm) lights. The sulfur content of the obtained diesel fuels was then reduced through the solvent extraction step. Maximum sulfur removals of ca 97 and 87 % were detected using the CdO (visible-light) and TiO2 (UV-light) respectively. The optimum conditions were then repeated under the sunlight where a removal of 98% was noticed. Ultra low sulfur diesel (ULSD) contains 25 ppm sulfur was eventually obtained via using the diesel fuel of the lowest sulfur content from stage one as a secondary feed. In the second stage, the UV irradiation and TiO2 were selected for the implementation of this operation.

Key words: Diesel Fuel, Desulfurization, Nanoparticles of oxides, Sulfur removal, Visible light, UV irradiation.