Synthesis of mesoporous materials SBA-16 with different morphologies and their application in dibenzothiophene hydrodesulfurization

Abstract

A series of mesostructured SBA-16 materials with different morphologies were prepared by templating method using triblock copolymer pluronic F127 (EO106PO70EO106) as surfactant and tetraethyl orthosilicate (TEOS) as silicon source. The influences of inorganic salt KCl and the synthesis temperature (temperature of the synthesis process before hydrothermal treatment) from 25 to 55°C on the morphologies of SBA-16 materials were also investigated. The obtained materials were characterized by various techniques, including X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), scanning electron microscope (SEM), transmission electron microscopy (TEM), N2 adsorption–desorption, UV–visible diffuse reflectance spectrum (UV–vis DRS), H2 temperature-programmed reduction (H2-TPR), Raman and X-ray photoelectron spectra (XPS) measurements. The SAXS, SEM and TEM results demonstrated that the SBA-16 materials possessed a body-centred cubic Im3m mesostructure. Five kinds of morphologies were found for the as-prepared SBA-16 materials, while sphere SBA-16 particles were obtained at the synthesis temperatures of 25°C and 30°C; mixed states of decahedral together with sphere were obtained at 38°C; decahedral together with dodecahedral was obtained at 45°C; hexagonal prisms was obtained at 50°C; and tetrakaidecahedron was obtained at 55°C. Moreover, aluminium isopropoxide was incorporated into the SBA-16 materials with a Si/Al molar ratio of 20 through the post-synthesized method, and the corresponding hydrodesulfurization (HDS) activities of NiMo supported catalysts on dibenzothiophene (DBT) were also performed in a micro reactor at T=340°C and P=4MPa with different weight hourly space velocities (WHSV). These NiMo catalysts were denoted as NiMo/S-x. S referred to Al modified SBA-16 supports, and x signified the synthesis temperatures from 25 to 55°C. The synthesis mechanism of SBA-16 exhibiting different morphologies was proposed. Meanwhile, the DBT (500ppm) HDS performance over NiMo/S-50 catalyst exhibited the highest conversion of 95.2% at the WHSV of 20h−1.