Synthesis of ultra-fine TS-1 catalyst with high titanium content and its performance in phenol hydroxylation

Abstract

Efficiently devising a strategy to synthesize titanium silicate-1 (TS-1) zeolite crystals with desired particle size and enriched framework titanium content for improved catalytic oxidation properties could be challenging. This study explores the incorporation of polyvinyl alcohol (PVA) and ammonium bicarbonate (NH₄HCO₃) as additives to decrease the particle size and increase the framework titanium content of TS-1, respectively. Powder X-ray diffraction (XRD), UV-vis absorption spectra, nitrogen adsorption–desorption, Fourier transform infrared (FT-IR) spectra, field-emission scanning electron microscopy (FESEM), and inductively coupled plasma (ICP) were used to characterize the TS-1 catalysts. The experimental results indicated that in the presence of NH₄HCO₃ and PVA (TS-1-S), the particle size and Si/Ti molar ratio of TS-1 were determined to be 170 nm and 43.55, respectively. Furthermore, the catalytic activity of the prepared catalysts in regard to the phenol hydroxylation with H₂O₂ has been evaluated. The TS-1-S sample showed a conversion of 29.52%, while the conversion of the conventional sample was 23.08%. This improvement can be attributed to the synergistic impact of reduced particle size and enriched framework titanium content.