Optimization of TiO2/SiO2 photocatalysts in a LED-irradiated gas-solid photoreactor for air treatment

An investigation on TiO2/SiO2 catalysts was performed, covering a wide range of TiO2 contents (0–100 % wt%) and calcination temperatures (150–1000 °C), which were applied to a continuous gas-solid photocatalytic reactor, irradiated by UV-LED for n-hexane degradation. A series of characterization analyses were conducted and the effects of the operational parameters and the catalyst stability over time were investigated. The TEM images confirmed the results of XRD crystallography, showing the preferential (101) anatase plane, in the form of 4–5 nm nanocrystals. Silica gel delayed the phase transformation from anatase to rutile even after calcination at 750 °C, while the band gap energy decreased from 3.21 to 3.06 eV with increasing calcination temperature from 150 to 1000 °C. The 20 %-TiO2 material calcined at 450 °C exhibited the best performance among 14 different materials, reaching a conversion rate of 2.7 × 10−7 mol g−1 min−1, n-hexane degradation of 40 %, maintaining its stability even after 20 h of continuous photoreaction, with resistance to TiO2 leaching and particle breakage. Therefore, the presence of silica significantly enhanced the properties of the catalyst, and contributed to improving its photocatalytic activity, making the use of these materials in gas-solid photoreactors a viable alternative for removing volatile organic compounds.