二氧化锆相结构的漫反射光谱表征

利用紫外漫反射光谱考察了二氧化锆基催化剂的表面相组成 ,结合X射线粉末衍射、差热分析和X射线光电子能谱研究了铂化以及Al2 O3 的引入对样品中ZrO2 体相和表面相结构的影响。结果表明 :通氢还原铂化过程使部分的ZrO2 由四方相向单斜相转化 ,而且在催化剂表面这一效应更为显著。随着基体中引入Al2 O3 量的增加 ,二氧化锆的相变温度不同程度地向高温转移 ,添加Al2 O3 使ZrO2 得到较好的分散并抑制单斜相二氧化锆的生成。

Diffusion Reflectance Spectroscopy of ZrO2 Phase Structure

Diffusion Reflectance Spectroscopy (DRS) was employed to study the surface phase structure of ZrO 2 based catalysts. The effect of calcining temperature, and the addition of Al 2O 3 and platinum on the surface and bulk phase structures of zirconia was studied by DRS combined with XRD, DTA and XPS. The same trend was observed that heating to higher temperatures results in the conversion to monoclinic zirconia in undoped samples, while incorporation of an appropriate amount of Al 2O 3 would stabilize the tetragonal phase zirconia. And the reduction processing of Pt/ZrO 2 affects crystallization and phase transitions, resulting in certain fraction of tetragonal ZrO 2 transferred to monoclinic ZrO 2. The DRS shows an appreciable difference in the corresponding XRD spectra that more monoclinic zirconia formed on the surface of catalyst during the reduction processing of Pt/ZrO 2, compared to the bulk of catalyst.