吸附相反应技术制备纳米TiO_2及其气相甲苯光降解特性

PHOTO-DEGRADATION CHARACTERISTIC OF GASEOUS TOLUENE BY NANO TiO_2 PREPARED BY ADSORPTION PHASE REACTION TECHNIQUE

以纳米SiO2粉体作为载体,釆用吸附相反应技术(adsorption phase reaction technique,APRT)在SiO2粒子表面制备纳米TiO2,研究了用水量、温度对纳米TiO2特性的影响,利用X射线色散能谱仪、透射电子显微镜与X射线衍射等研究了SiO2粒子表面TiO2含量、TiO2形貌和晶型的变化规律。利用气相甲苯的光降解实验评价不同样品的光催化活性,采用一级反应动力学拟合得到动力学常数。结果表明:催化剂中锐钛矿型TiO2的形成可以提高其光催化活性。随着制备水量的增加,SiO2表面TiO2含量和样品中锐钛矿型TiO2含量都增加。TiO2催化活性的增加与载体表面TiO2含量增加有着明显的相关性;随着制备温度的升高,载体表面的Ti含量很快下降,光催化活性却变化不大,这可能与吸附层的变化导致分散均匀性的改变有关。

The influence of water concentration and temperature during preparation on the characterization of TiO2 nanoparticles pre- pared via adsorption phase reaction technique was studied. Energy dispersive X-ray analysis, transmission electron microscopy and X-ray diffraction were employed to measure the TiO2 content on the SiO2 surface, and to investigate the morphology and crystallinity of the TiO2. The photocatalytic activity of the TiO2 catalysts was measured by photodegradation of gaseous toluene. The results indicate that the photocatalytic activity of TiO2 catalysts can be promoted greatly due to the appearance of anatase TiO2. The Ti concentration on the SiO2 surface and the amount of anatase TiO2 in the prepared TiO2particles increase with the increase of water content in the preparation. With the increase of preparation temperature, the TiO2 content on the support surface decreases quickly; however, the photocatalytic activity of TiO2 changes little, and this phenomenon might be due to the change of dispersibility of TiO2 on the SiO2 surface with the change of the adsorption layer.