Synthesis and Characterization of Silicon-Doped Mesoporous SO42–/TiO2 without Using Organic Templates

Mesoporous metatitanic acid was prepared from industrial TiOSO4 solution without using templates. Si-doped mesoporous SO42–/TiO2 with high thermal stability was then synthesized by impregnating mesoporous metatitanic acid with tetraethylorthosilicate solution and calcination. The calcined samples were characterized by X-ray diffraction, N2 adsorption and desorption, scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The photocatalytic activity of Si-doped SO42–/TiO2 for the degradation of methylene blue was tested. Tetraethylorthosilicate that was adsorbed in the pores of metatitanic acid formed Ti–O–Si bond by reaction with free –OH on the pore walls of metatitanic acid during calcination. Silicon atoms introduced into the framework of TiO2 act as the pore structure support, and thus the thermal stability of mesoporous SO42–/TiO2 was improved. The sample calcined at 700 °C for 2 h had a surface area of 189 m2/g and an average pore diameter of 2.8 nm. The photocatalytic activity of the sample calcined at 400 °C was excellent.