纳米TiO2-SiO2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

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)。

A Study on the Preparation and Photocatalytic Properties of TiO2-SiO2 Nanocomposite Photocatalyst by Supercritical Fluid Drying

TiO₂-SiO₂ nanocomposite photocatalysts were prepared with Na₂SiO₃·9H₂O and TiCl₄ as precursors by chem-istry coating processes and supercritical fluid drying (SCFD) method. Morphology and structure of the photocata-lysts 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 ex-perimental 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%.