超临界制备TiO_2光催化剂及其活性研究

Study on the Preparation and Activity of Efficient TiO_2 Photocatalyst Based on Supercritical Drying Technology Degradation

以钛酸丁脂为钛源,用溶胶-凝胶法制得催化剂前驱体,用超临界干燥法处理获得大孔及高比表面积的TiO_2超细颗粒,该样品在苯酚光催化降解反应中显示出优良的催化性能,其催化活性显著优于由直接干燥法处理获得的TiO_2颗粒,而且催化剂具有良好的热稳定性,即使经过973 K的高温焙烧,仍能保持良好的催化活性,结合催化剂的系列表征,包括XRD、TEM、氮气吸附-脱附等温线、XPS等,初步讨论了超临界干燥法对改善TiO_2光催化活性的结构因素。

Based on the precursor prepared via Sol-gel method from Tetrabutyltitanate (Ti(OC4H9)4),a novel ultrafine TiO2 photocatalyst with very large pore size and pore volume as well as specific surface area was obtained via supercritical drying,followed by calcinations at various temperatures.The as-prepared TiO2 particles exhibited much higher activity than the corresponding counterpart obtained through direct drying in liquid phase photocatalytic degradation of phenol.In addition,it also showed much higher thermal stability for its anatase structure,which could be remained unchangeable after calcined at 973 K for 2 h.This could account for the excellent activity of the as-prepared TiO2 particles after being calcined at 973 K.Based on various characterizations,such as XRD,XPS,TEM,BET,etc.,the relationship among the photocatalytic activity of the TiO2 particles,the structural characteristics and its surface electronic state was discussed.The results demonstrated that the crystalline phase of the TiO2 particles (anatase phase rather than rutile phase) and the crystalline degree played a key role in its activity,while other structural properties or the surface electronic state had only little effects.