Removal of Dibenzothiophene from Liquid Fuels by Photocatalytic Desulfurization over Zn-Terephthalate Complex: A Process Modelling and Optimization by Response Surface Methodology

The Zn-terephthalate complex was synthesized by hydrothermal method at 180 degrees C and applied as a novel macroporous photocatalyst in the desulfurization of dibenzothiophene (DBT) from a fuel model to produce DBT sulfone. The physical-chemical properties of the photocatalyst were characterized by Fourier Transform Infrared (TIR), Raman spectroscopy, powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), photoluminescence spectroscopy and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The characterization results indicated the formation of mono-nuclear paddlewheel metal-organic framework (MOF) as Zn [COO](2) frameworks. The photocatalytic experiments were designed by the Box-Behnken method of response surface methodology (RSM) and the photocatalytic process was modelled and optimized. Three independent process variables i. e. concentration of dibenzothiophene, the amount of photocatalyst and light irradiation time were considered in the experimental design. The determination coefficient (R-2) of the model is 0.97. The optimum removal of DBT (50.4 %) resulted in a fuel model containing 50 ppm DBT, desulfurized by 0.060 g of Zn-MOF photocatalyst under visible light for 180 min. The predicted response (DBT removal%) by the RSM model was 50.68 %. According to the Pareto analysis, the order of importance of independent factors on the response was as follows: Irradiation time>m(photocatalyst)>C(DBT).