南京林业大学.doc

南京林业大学
本科毕业设计(论文)
题目:介孔二氧化钛光催化剂的制备及分形结构研究
学院: 理学院
专业: 高分子材料与工程
学号: 070804110
学生姓名: 黄华
指导教师: 刘福生
职称: 教授
二O一一年六月一日
介孔二氧化钛光催化剂的制备及分形结构研究
摘要:本文以钛酸四丁酯、自制模板A、B为原料制备了多孔TiO2,并采用X射线衍射(XRD)、紫外可见漫反射光谱(UV-Vis)和比表面积和孔隙分析仪对所制备的多孔TiO2光催化剂进行了结构表征。XRD表征结果表明用模板A制备的介孔TiO2主要以锐钛晶型存在;以模板B制备的介孔TiO2,存在金红石晶型。随着模板添加量的增多,晶格常数(a,c)开始变小。a和c变化幅度和趋势基本相同,表现为各向同性。样品的禁带宽度计算结果表明:样品的禁带宽度都有不同程度的减小,说明晶格存在缺陷。
此外,本文用分形模型来描述多孔材料的孔结构。首先,通过BET吸附模型法计算得到了介孔TiO2的分形维数,再通过分形维数建立TiO2的孔结构与孔容和比表面积的定量关系,并以此对介孔TiO2的孔容和比表面积进行了计算。计算结果表明:分形模型计算得到的介孔TiO2的孔容和比表面积更接近实验数据,因此,可以证实介孔TiO2的孔道形状主要为分形柱孔。
以上结论为预测多孔材料的孔结构数据提供了理论依据。
关键词:介孔 TiO2 分形
Preparation and Fractal Characterization of
Mesoporous TiO2 Photocatalyst
Abstract
In this paper, the mesoporous TiO2 was prepared by Tetra-n-butyl Titanate with self-made template A and template B. The products were characterized by X-ray powder diffraction (XRD), ultraviolet and visible spectrum (UV-Vis), surface area and pore volume analyzer. The results by XRD showed that the crystal of mesoporous TiO2 by template A was anatase while the crystal of mesoporous TiO2 by template B existed rutile.
With the increasing of the amount of template, the lattice constants a and c decreased. The change of and was at same amplitude and trends, and the crystal expressed as isotropy. The band gap of mesoporous TiO2 was calculated through the results of UV-Vis. The band gap decreased for existing lattice defects.
In addition, the fractal model is used to describe the pore structure of porous materials. Firstly, the BET adsorption model are used to calculate fractal dimension of the mesoporous TiO2, and then through the fractal dimension, the quantitative relationship between pore structure and pore volume and specific surface area of TiO2 is established. The results showed that pore volume and specific surface area calculated by fractal model was more closing to the experimental data. So the shape of pores of mesoporous TiO2 could be described as fractal structure.
The above c