纳米TiO_2-SiO_2复合光催化剂的超临界流体干燥法制备及其光催化性能研究

A Study on the Preparation and Photocatalytic Properties of TiO_2-SiO_2 Nanocomposite Photocatalyst by Supercritical Fluid Drying

本文以廉价无机盐Na2SiO3·9H2O和TiCl4溶液为原料,采用化学包覆结合超临界流体干燥(SCFD)法制备纳米级TiO2-SiO2复合光催化剂。利用XRD、TEM、NMR等手段对复合粉体进行了表征。结果表明,采用超临界流体干燥法可直接制得锐钛矿型TiO2-SiO2纳米复合光催化剂,其中SiO2以单分散、无定形形式存在。以苯酚和邻苯二酚紫光催化降解为反应模型,考察了TiO2-SiO2复合光催化剂的催化性能。证明掺入适量SiO2的TiO2-SiO2纳米复合光催化剂既减少了TiO2的用量、降低了成本,又在某种程度上提高了TiO2的光催化活性。SiO2的引入可以有效抑制纳米粒子粒径的长大和晶相的转变,增强了二氧化钛纳米粒子的热稳定性。二氧化硅的最优掺杂量为15%(质量分数)。

TiO2-SiO2 nanocomposite photocatalysts were prepared with Na2SiO3 . 9H(2)O and TiCl4 as precursors by chemistry coating processes and supercritical. fluid drying (SCFD) method. Morphology and structure of the photocatalysts were characterized by XRD, TEM and NMR. The results displayed that the anatase TiO2-SiO2 were directly synthesized by supercritical fluid drying technology. SiO2 remained monoseparated and amphorous at all samples. Application of the TiO2-SiO2 composite catalysts for the photocatalytic decomposition of phenol and pyrocatechol violet not only gave improved activity in some degree, but also reduced quantity of TiO2 and saved cost. The experimental results also proved that right amount Of SiO2 doping could hold up the growth of the size of nanopaticle and transformation from anatase to rutile, the thermal stability of TiO2 was enhanced greatly. The optimum doping of SiO2 is 15%.