吸附相反应技术用于不同载体表面纳米TiO2的制备

研究了不同载体对吸附相反应技术制备TiO2粒子的影响, 设计了两种不同表面形貌载体的温度实验(A型SiO2: 粒径20 nm, 比表面积640 m2·g-1; B型SiO2: 粒径12 nm, 比表面积200 m2·g-1), 并用电子能谱仪测定了两种载体表面TiO2含量随温度的变化. 结果表明, 两种载体表面Ti含量都随着温度的升高而减少, 且在一定温度范围内存在着突变, 但A载体突变的温度范围是40-60 ℃, 而B载体为30-50 ℃. TEM表征结果则显示, B表面TiO2粒子要比A表面的均匀. XRD得到的晶粒粒径曲线表明, A 载体表面TiO2晶粒粒径随着温度升高而减小并存在着突变, B载体表面粒子粒径则基本不变. 根据硅胶表面的吸附特性, 提出SiO2吸附的共性导致载体表面Ti含量变化曲线存在着共同点, 而载体内外表面的不同形貌则引起其表面吸附层的形貌以及温度敏感性不同, 最终导致两种载体表面Ti含量、晶粒粒径以及形貌上的差别.

Preparation of TiO2 Nanoparticles on Surface of Different Supports by Adsorption Phase Reaction Technique

The influence of supports on the preparation of TiO2 nanoparticles in adsorption phase nanoreactor formed by the adsorption layer on silica surface was studied. Series temperature experiments of two types of supports (support A: size 20 nm, specific surface area 640 m2·g-1; support SiO2 B: size 12 nm, surface area 200 m2·g-1) were designed. Electronic energy spectrum indicated that the concentration of TiO2 on the two supports both decreased with temperature increasing. TiO2 quantity on support A decreased sharply between 40-60 ℃, whereas the coresponding temperature range for support B was between 30-50 ℃. TiO2 particles on support B were more uniform than those on support A in TEM. The grain size curve by XRD suggested that size of TiO2 particles on support A reduced with temperature rising and there was also a sharp decrease as in quantity curve of TiO2, but TiO2 particles on support B had a substantially constant size. Based on the characteristics of adsorption on silica surface, the generality of adsorption on SiO2 was proposed to explain the same changes in Ti concentration on different supports. The different characteristics of internal/external surface induced variant temperature-sensitivities and characteristics of adsorption on support surface. Moreover these different adsorptions led variance of content and grain size, as well as characteristics of TiO2 on the two types of supports.