Solvothermal synthesis of mesoporous TiO2: The effect of morphology, size and calcination progress on photocatalytic activity in the degradation of gaseous benzene

Abstract

The photocatalytic activity of a mesoporous anatase TiO2 catalyst, which was prepared using a solvothermal method, was studied for the degradation of gaseous benzene under UV irradiation. The optimal synthesis conditions, which utilised acetic acid/butyl titanate (5:1 v/v) with calcination at 400°C, were determined, and nanopores in the prepared samples were found. The newly prepared TiO2 powders were characterised using X-ray diffractometer (XRD), scanning electronic microscopy (SEM), Brunauer–Emmett–Teller (BET) N2 adsorption, transmission electronic microscopy (TEM) and high resolution transmission electronic microscopy (HRTEM). The effects of the different morphologies, sizes and calcination temperatures on the photocatalytic activity of the prepared samples were discussed in detail. Nano-sized TiO2 particles that were synthesised under optimal conditions show the largest specific surface area (130.3m2/g), which is nearly two times that of Degussa P25. These particles also have the highest efficiency, which is significantly higher than was observed with Degussa P25. A modified Langmuir–Hinshelwood kinetic model was used considering a pseudo-steady state approach in order to explain the dependence of the apparent reaction rate constant and the apparent Langmuir adsorption constant on light intensity. Different intermediates in the samples used during the photocatalytic degradation of benzene have been identified using GC–MS analysis. A detailed reaction mechanism is proposed to explain their formation.