Efficient Synthesis of Titaniosilicalite-1 Zeolite Nanoparticles Under Solvent-free Conditions for the Oxidation of Dibenzothiophene: Impact of Silica Precursor

摘要

abstract_textpVarious silica precursors of tetraethyl orthosilicate (TEOS), mesocellular silica foam (MCF), and a combination of TEOS and MCF are investigated under solvent-free conditions to achieve efficient TS-1 catalyst. The obtained TS-1 catalysts were characterized by powder XRD, FTIR, diffusive reflectance UV-Vis, FE-SEM, TEM, N-2 sorption, DLS, and EDS. The TS-1 synthesized by combination of TEOS and MCF possesses smaller crystal size, higher yield of solid materials, and enhanced Ti incorporation than that obtained by either only MCF or TEOS. The average particle size of TS-1 catalysts synthesized by using MCF, TEOS, and the combination of TEOS and MCF were about 350, 170, and 105 nm, respectively. The yield of solid TS-1 by using MCF, TEOS, and the combination of TEOS and MCF were 0.28, 0.80, and 1.20 g-TS-1/g-TPAOH, respectively. Oxidation of 1000 ppm of the bulky substrate of dibenzothiophene (DBT; kinetic diameter 0.9 nm) by TS-1 synthesized by combination of TEOS and MCF was about two times higher than that by the TS-1 catalyst prepared either by TEOS or MCF. Furthermore, oxidation of 5000 ppm of DBT (equally to 5 separate batches) by this catalyst resulted in full conversion in 24 h. Consequently, the use of combination of TEOS and amorphous silica of MCF as silica precursor under solvent-free conditions is a practical approach to prepare efficient TS-1 catalyst./p/abstract_text