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

Abstract

Various 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.

Crystallization of as-Mesocellular Silica Foam into Hierarchical TS-1 Zeolites by Conventional Hydrothermal and Dense-Gel Routes for Oxidation Reactions

“…The DR UV–vis spectra of the TS-1 samples (Figure S6) showed absorbance at about λ = 220 nm for both TS-1- h and TS-1- d corresponding framework Ti and almost no absorbance at about λ = 310 nm, indicating the absence of the anatase TiO 2 phase . The obtained TS-1 materials by the transformation of as-MCF showed higher framework Ti than that by either TEOS and/or MCF (Table S2), suggesting the synergetic impact of the organic template and silica wall of MCF in the enhancement of framework Ti.…”

Improvement of adsorption and catalytic properties of zeolites by precisely controlling their particle morphology

“…The great effect of the silica source on the zeolite crystal size is revealed by the synthesis of TS-1. 39 Mesocellular silica foam (MCF) and tetraethyl orthosilicate (TEOS) result in the formation of 350 nm and 170 nm crystals, respectively, whereas the co-use of these two materials produces 105 nm crystals This journal is © The Royal Society of Chemistry 2022…”

New avenues for mechanochemistry in zeolite science

“…45 The procedure has also been extended to include aluminophosphate, 46,47 silicoalumino-phosphates, 46,48,49 and heteroatom containing zeolites. [50][51][52][53] Several groups have recently tried to elucidate the underlying mechanism of these new zeolite syntheses. In the study on zeolite A (LTA), Xiao and co-workers were able to show that after manual grinding of the solid reagents a zeolite phase formed after heat treatment for 3 h. 54 The crystallinity can be increased by longer treatment for up to 5 h, which is still faster than most conventional synthesis methods.…”