Sungmin Chin

Synthesis and photocatalytic activity of TiO2 nanoparticles prepared by chemical vapor condensation method with different precursor concentration and residence time.

Nanosized TiO(2) photocatalysts were synthesized using a chemical vapor condensation method under a range of synthesis conditions (precursor vapor concentration and residence time in a tubular electric furnace). X-ray diffraction showed that the prepared TiO(2) powders consisted mainly of anatase (>94%) with a small amount of rutile. The mean particle diameter from the Brunauer-Emmett-Teller surface area and transmission electron microscopy measurements ranged from 9.4 to 16.6 nm. The specific surface area (92.5-163.5 m(2) g(-1)) of the prepared TiO(2) powders was found to be dependent on the synthesis conditions. The content of hydroxyl groups on the surface of the prepared TiO(2) sample was higher than those on commercial TiO(2), resulting in increased photocatalytic oxidation. The photocatalytic activity of the TiO(2) samples prepared in a methylene blue solution was strongly dependent on the crystallinity and specific surface area, which were affected by the TTIP vapor concentration and residence time.

A Study on TiO2 Nanoparticle-Supported Mn2O3 Catalyst for Indoor Air Pollutants - Ozone and VOC Decomposition Reaction

The catalytic conversion of toluene on MnOx/TiO2 catalysts was examined in the presence of ozone. The MnOx/TiO2 catalysts were prepared by a wetimpregnation method. A set amount of manganese acetate was dissolved in distilled water. The TiO2 nanoparticles, as the support materials in this study, were synthesized by a thermal decomposition process. The generation of TiO2 nanoparticles by the thermal decomposition of titanium tetraisopropoxide (TTIP) was carried out in an electric tune furnace. The TiO2 nanoparticles were characterized by X-ray diffraction, Brunauer-Emmett-Teller measurements and transmission electron microscopy. Compared to the commercial photocatalyst (P25), the TiO2 nanoparticles prepared at 900°C had a small particle size (10.5 nm), pure anatase phase and a high degree of crystallinity with a dense polyhedral structure. The concentration of toluene was varied in the range of 20-100 ppm and the ozone to toluene ratio was increased from 1.0 to 15.0. The reaction temperature was controlled between 25-100°C and the space velocity was fixed at 20000 h-1. The COx selectivity was enhanced considerably by the catalyst supported on TiO2 (thermal decomposition process) after injecting ozone. The activity of the catalyst depended mainly on the support used. The catalyst synthesized by the thermal decomposition process was found to be the most active support.