吸附相反应技术制备纳米TiO_2的反应过程

Reaction Mechanism of Preparation of Nano TiO_2 by Adsorption Phase Reaction Technique

通过不同水量实验并结合同样条件下的浸渍法实验,研究了吸附相反应技术吸附层中钛酸丁酯的反应过程。用分光光度法测定乙醇体相中 Ti 含量随反应时间的变化,发现有外加水的条件下,Ti 含量曲线都呈现先快后慢的变化趋势,且水量在1.0～1.1 mL 时 Ti 含量曲线出现突变。Ti 含量的突变区域通过电子色散能谱仪对载体 SiO_2表面 Ti 含量的测定得到了进一步地确定,但浸渍法得到样品的 Ti 含量变化非常缓慢。透射电子显微镜(TEM)和 X 射线衍射(XRD)分析结果表明,吸附法得到的 TiO_2粒子粒径远远小于浸渍法得到的 TiO2,而且在 Ti 含量较高时也能保持非常高的分散性。实验结果发现,由于纳米级吸附层作为反应器的独特性,钛酸丁酯在吸附层中发生的反应有着不同于宏观反应的特点。

Reaction of tetrabutyl titanate in adsorption layer was investigated by adsorption phase reaction technique （APRT） under different water concentration combining with impregnation method （IMP） under same condition. The change of Ti concentration in ethanol bulk during reaction was determined by spectrophotometry and it showed a rapid decrease at beginning then became slowly. When water volume was between 1.0 mL and 1.1 mL the Ti concentration in bulk presented a jump, which corresponded to similar phenomena of the Ti concentration on SiO2 surface from energy dispersive X-ray microanalysis. But Ti concentration of IMP samples changed slight when water changing from 1.0 mL and 1.1 mL. Transmission electron microscope （TEM） and X-ray diffraction （XRD） showed that the size of TiO2 particles by APRT was much smaller than that of the particles by IMP, and high dispersibility of particles by APRT was kept at high Ti concentration. It was found that the reaction of tetrabutyl titanate in adsorption layer was different from macrodynamics of tetrabutyl titanate.