Crystallization mechanism and catalytic performance of TS-1 synthesized by an aerosol-assisted method†
TS-1 was synthesized by an aerosol-assisted method. SiO2–TiO2 amorphous powder was prepared by an aerosol process from an aqueous solution of silicon and titanium sources under acid conditions, which can make titanium ions highly distributed without complex operations. The powder was crystallized with a given amount of template agent (25% TPAOH) under autogenous pressure. Without adding extra water, the crystallization system maintained a high concentration of template agent, which can significantly reduce the amount of template and the discharge of polluted water. TS-1 with different Si/Ti ratios and different crystallization times were synthesized from the SiO2–TiO2 amorphous powder by the aerosol-assisted method. The structure, composition and morphology of TS-1 were characterized by X-ray diffraction, UV-vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray fluorescence spectrometry (XRF) and electron microscopy. The crystallization mechanism of TS-1 has been studied at different crystallization times. The results indicated that the crystallization process followed a liquid-phase mechanism. The incorporation of the Ti species into the framework was delayed as compared to that of the Si species. Furthermore, TS-1 exhibited good catalytic performance in propylene epoxidation with hydrogen peroxide.