Fabrication of fibrous silica zinc (FSZn) composite for enhanced photocatalytic desulphurization

Abstract

Novel fibrous silica zinc (FSZnIS) catalyst was synthesized by in-situ hydrothermal-microwave method and the catalyst was analyzed by X-ray Diffraction (XRD), N2 physisorption, Field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) and photoluminescence (PL). The catalyst was employed in photocatalytic desulphurization of dibenzothiophene (DBT) in model fuel. The performance of FSZnIS was compared with bare fibrous silica (KCC-1), commercial ZnO and fibrous silica zinc prepared by impregnation method (FSZnIP). The photoactivity towards catalytic desulphurization of DBT is in the following order: FSZnIS (88.9%) > FSZnIP (62.4%) > KCC-1 (53.9%) > ZnO (44.4%). The best performance was achieved using 0.375 gL−1 of FSZnIS catalyst over 100 mgL−1 DBT in model fuel. This is predominantly due to the well distribution of ZnO on KCC-1, high surface area (411.2 m2 g−1), high number of Si–O–Zn bonds, appropriate band gap energy (2.95 eV), and proficient charge separation. These criteria mutually encouraged effective harvesting of visible light (420 nm) and good mobility of charge carriers for enhanced visible light driven performance. A kinetics study determined by Langmuir–Hinshelwood model demonstrated that the photodesulphurization obeyed the pseudo-first-order and adsorption was the rate-limiting step.