Development of integrated approach employing Fe/TiO2-[BMIM]FeCl4 system for sulfur removal from model oil

This project researchs on the development of TiO2 semiconductors doped with Iron, Fe as the photocatalyst and ionic liquid, [BMIM]FeCl4 for desulfurization process of model oil. Current technology for desulfurization requires severe process conditions; high pressure and temperature in order to remove the sulfur compounds in crude oil. Therefore, research is being conducted to develop better desulfurization process employing photocatalysis and liquid-liquid extraction conducted at atmospheric pressure and temperature in the presence oxygen. TiO2 was selected as the photocatalyst but not active in visible light. So, modification was done by doping the TiO2 photocatalyst with transition metals, Iron, Fe. Transition metal doping is able to enhance the photoexcitation of electrons in the photocatalyst when only subjected to visible light. Besides, it can act as charge carrier trapper for both photogenerated electrons and holes thus inhibiting the electron-holes recombination for longer time. Wet Impregnation method was chosen to prepare iron-doped catalyst, using Iron(III) Nitrate, Fe(NO3)3 as starting materials. The dopant loading varied from 0.4 to 0.8wt% and two calcination temperatures were selected which are 400°C and 500°C. Characterization of the modified photocatalysts were done by X-Ray Diffraction (XRD), UV-vis Diffuse Reflectance Spectra (UV-vis DRS), Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier Transform Infrared Spectroscopy (FTIR). In this project, 1-butyl-3-methylimidazolium tetrachloroferrate , [BMIM]FeCl4 was preferred as the ionic liquid for liquid-liquid extraction process as it involved same element with the transition metal doped to TiO2. [BMIM]FeCl4 was prepared by mixing together anhydrous Iron(III) Chloride, FeCl3 and 1-butyl-3-methylimidazolium chloride, [BMIM]Cl. The desulfurization analysis using halogen lamp and Gas Chromatography, GC analysis was done to investigate the photocatalytic activity of the modified photocatalysts and extraction process by ionic liquid. It was found that 0.6wt% of Fe/TiO2 calcined at 400°C yield, thus chosen for the integrated approach combining with ionic liquid, [BMIM]FeCl4. The integrated approach also showed the increment of sulfur removal from using photocatalyst and model oil alone. The reduction of band gap as a result of doping was estimated and the influence of the process parameters on catalytic activity is explained.