Characterization of SO4 2−/TiO2 and its catalytic activity in the epoxidation reaction

Abstract

The solid acid catalysts SO4 2−/TiO2 were prepared by the impregnation technique under two preparation conditions which were different in calcination temperature and concentration of impregnation solution of H2SO4. The characterization was carried out by using Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), temperature programmed desorption of NH3 (NH3-TPD), N2-BET, X-ray fluorescence and thermal gravity (TG)–differential scanning calorimetry (DSC). The characteristic peaks in the FTIR spectrum were essentially the same within the calcination temperature range of 400–600 °C. The XRD results indicated that the sample could show partial specific peaks of the anatase phase as the calcination temperature was higher than 400 °C. The obvious strong acid and superacid sites of the prepared SO4 2−/TiO2 were conformed by the NH3-TPD results. The BET surface areas of 102–206 m2/g were measured by the N2-BET method, and the pore size distributions were essentially mesoporous. The TG–DSC results showed that SO4 2−/TiO2 would decompose at about 500 °C in the air. The solid acid SO4 2−/TiO2 were used for the epoxidation of castor oil. The lowest iodine value of the product was 52.65/100 g when the reaction temperature was 65 °C, reaction time was 10 h and catalyst loading was 15 wt.%.