负载型贵金属催化剂中活性组分非均匀型分布的研究

Study on non-uniformity distribution of active component in supported noble metal catalysts

采用饱和浸渍法与涂覆法制备出负载于氧化铝载体上活性金属呈非均匀分布的贵金属催化剂,并采用活性组分显色,电子探针对活性组分在载体中分布进行表征研究。结果表明对催化剂进行显色处理和光学显微照相,及用电子探针微量分析(EPMA)仪分析表征Pd和Pt在剖面上的分布,可确定活性组分在载体中非均匀分布情况。采用浸渍法制备催化剂时,添加竞争吸附剂,可得到Pd或Pt在载体中呈蛋壳型、蛋白型、蛋黄型或均匀型几种不同分布结构;采用涂覆法制备催化剂时,可得到所需壳层厚度的蛋壳型贵金属催化剂,活性金属主要集中在载体外表面。

Studies on non-uniformity distribution of active component were performed on noble metal catalysts which were supported on alumina by dry impregnation method and coating method.The distributions of active component in the support were studied by color disposal,micrographic and EPMA.The results showed that the situation of distribution of active component in support can be ascertained by these methods.By impregnation method and under the function of competition sorbent,different distributions of active component were gained such as egg-shell distribution,egg-white distribution,egg-yolk distribution and uniformity distribution.By coating method,the egg-shell distribution noble catalysts can be prepared and active component located at the outside surface of support.