纳米TiO_2光催化剂的酸催化水解合成与表征

Preparation and Characterization of Nanosize TiO_2 Photocatalyst Obtained via Acid Catalyzed Hydrolysis Method

以TiCl4为钛源,采用酸催化水解法控制TiCl4水解速度,合成了纳米TiO2光催化剂。以苯酚的光催化降解为模型反应,考察了酸催化剂种类、水解温度、煅烧温度对TiO2光催化活性的影响。采用X射线衍射(XRD)、紫外-可见漫反射(DRS)、扫描电镜(SEM)、低温氮物理吸附,分析了TiO2光催化剂的晶相结构、光谱特征以及表面形貌。结果表明,以HCl为催化剂、水解温度98℃、煅烧温度500℃下制得TiO2活性最高。最佳条件下合成的TiO2前驱体为无定型结构,400℃煅烧时几乎完全转化为锐钛矿相,800℃时完全转化为金红石相。随着煅烧温度升高,TiO2光吸收阈值红移,TiO2粒子尺寸增大,比表面积下降,光催化活性降低。

An acid was used as the catalyst to adjust the hydrolysis rate of TiCl4 , and a high active nanosize TiO2 photocatalyst was obtained by means of acid catalyzed hydrolysis method. Various preparation parameters such as the kind of acid catalysts, hydrolysis temperature and calcination temperature were optimized by means of phenol degradation. XRD, DRS, SEM and N2 adsorption isotherm were used for the characterization of TiO2 photocatalyst. The optimal preparation conditions were determined as： catalyst： HCl, hydrolysis reaction temperature：98 ℃, and calcination temperature：500 ℃. The prepared TiO2 precursor was uncrystalline. With the increasing of calcination temperature, uncrystalline was transformed into anatase, accompanyed with the threshold red-shift, SBET decreased and particle size increased. Completely transformation of anatase to rutile can be realized at 800 ℃.