PrO_y-ZrO_2固溶体的结构表征和CO氧化性能

PrO_y-ZrO_2 Solid Solution: Characterization and Catalytic Oxidation of CO

采用共沉淀法制备了不同Pr/Zr比的PrOy-ZrO2固溶体,用激光拉曼光谱(Raman)、X-射线粉末衍射(XRD)、紫外可见吸收光谱(UV-Vis)等技术对固溶体进行了物相结构表征并选择CO氧化作为模型反应考察了固溶体的催化性能。结果表明,随着Pr含量的增加,无定形ZrO2转化为晶相ZrO2的温度提高、热效应下降,而PrOy-ZrO2固溶体的物相结构从单斜相逐步向四方和立方相转变。XRD和Raman光谱得到的物相结构的差别是PrOy-ZrO2固溶体的表层和体相结构不一致造成的,PrOy-ZrO2固溶体表层更易生成低对称性的物相,而且也容易生成非晶相的物相。CO氧化实验表明PrOy-ZrO2固溶体的催化活性与样品的组成有很大关系,其中高温区和低温区分别是PZ-30和PZ-50的CO氧化活性最高。

Characterization for PrOy-ZrO2 solid solutions prepared by coprecipitation was performed by means of Raman, XRD, UV-Vis and CO oxidation. It is found that with increasing content of Pr, crystallization temperature of amorphous ZrO2 increases and heating effect of crystallization decreases. At higher Pr content, phase transformation towords a higher-symmetrical phase （tetragonal or cubic） was observed. The phase composition obtained by Raman spectra is different from that by XRD, which implies a structure difference between the surface and the bulk of the samples. The CO oxidation activity highly depends on the content of Pr. For CO oxidation, PZ-30 presents the best performance at high reaction temperature, while PZ-50 presents the best performance at low reaction temperature.