超临界流体干燥法制备TiO2/ Fe2O3 和TiO2/ Fe2O3/ SiO2 复合纳米粒子及光催化性能

以TiCl₄ 、Fe (NO₃ )₃·9H₂O 和Na₂SiO₃19H₂O 为原料, 采用溶胶凝胶法结合超临界流体干燥法(SCFD)制备了纳米级TiO₂/ Fe₂O₃ 和TiO₂/ Fe₂O₃/ SiO₂ 复合光催化剂。以光催化降解苯酚对所得催化剂的催化活性进行了评价。结果表明, 纳米TiO₂/ Fe₂O₃ 复合粒子与单组分TiO₂ 比较, 复合粒子光催化活性高于单组分的TiO₂, 6h 苯酚降解率高达95.9 %。SiO₂ 的加入可以抑制纳米粒子粒径的长大和晶相的转变, 增强TiO₂ 纳米粒子的热稳定性。复合光催化剂中Fe₂O₃ 最佳掺入量为0.06 %, SiO₂ 最佳掺入量为10 %(摩尔分数) 。并用XRD、TEM 和FTIR 等手段进行了表征。TiO₂ 以锐钛矿型形式存在, SiO₂ 以无定性形式存在。比较了不同制备方法制得的TiO₂/ Fe₂O₃ 复合光催化剂, 得出超临界干燥法制备的光催化剂具有粒径小、比表面积大、分散性好、光催化活性高等特点。采用超临界流体干燥可直接得锐钛型纳米复合光催化剂。

PREPARATION AND PHOTOCATALYTIC PROPERTIES OF TiO2/ Fe2O3 ANDTiO2/ Fe2O3/ SiO2 NANO-COMPOSITE PHOTOCATALYST BYSUPERCRITICAL FLUID DRYING

TiO2/ Fe2O3 and TiO2/ Fe2O3/ SiO2 nanocomposite photocatalysts were prepared with Na2SiO3 ·9H2O , Fe(NO3 )3·9H2O and TiCl4 as precursors by chemistry coating processes and supercritical fluid drying (SCFD ) methods. Thephotocatalytic activity was evaluated by photocatalytic degradation of phenol as model reaction. Characterizations withXRD , TEM and FTIR show that in addition to anatase type TiO2 is also formed in the range of the studied doping concentration , and SiO2 remains amorphous at all samples. It could hold up the growth of the nanoparticle size and transformation from anatase to rutile. Compared with pure TiO2 , or TiO2/ Fe2O3 catalyst prepared by sol-gel method , nano-composite photocatalyst shows significant improvement in catalytic activity : The photocatalytic degradation rate of phenolin 6 h reached 9519 %. The optimum doping of Fe2O3 is 0106 %. Application of the TiO2/ Fe2O3/ SiO2 composite catalysts for the photocatalytic decomposition of phenol could not only give the same activity relative to pure ultrafine TiO2 ,but also reduce cost . The experimental results prove that the thermal stability of TiO2 is greatly enhanced after mixingwith slight amount of SiO2 . The optimum doping of SiO2 is 1010 %. The photo-catalytic particles prepared by SCFD combination technology have small size , large surface area and high activity.