超薄切片与高角环形暗场像联用表征Pd/Al_2O_3催化剂贵金属的分散性  

CHARACTERIZATION OF NOBLE METAL DISPERSION OF Pd/Al_2O_3 BY ULTRATHIN SECTIONS AND HADDF IMAGE

作　　者：杨卫亚[1] 凌凤香[1] 沈智奇[1] 王少军[1] 张会成[1] Yang Weiya Ling Fengxiang Shen Zhiqi Wang Shaojun Zhang Huicheng(Fushun Research Institute of Petroleum and Petrochemicals, SINOPEC, Fushun 113001, Liaoning, China)

机构地区：[1]中国石化抚顺石油化工研究院,辽宁抚顺113001

出　　处：《精细石油化工》2017年第4期1-4,共4页Speciality Petrochemicals

基　　金：中国石油化工股份有限公司资助项目(YK515035)

摘　　要：通过超薄切片与高角环形暗场像联用表征蒽醌加氢制双氧水Pd/Al_2O_3催化剂贵金属的分散性,提出了以平均尺寸、尺寸分布、空间粒子密度及表面原子分散度4个指标全面评估负载型贵金属催化剂金属分散性质的方法。实验结果显示,Pd/Al_2O_3催化剂切片厚度以30~40nm较为适宜,能够获得幅面更大的试样薄区,从而根据高角环形暗场像得到催化剂的平均尺寸、尺寸分布、空间粒子密度及表面原子分散度的信息。超薄切片与高角环形暗场像联用可以克服化学吸附法及普通TEM表征贵金属分散度的不足。所述的组合表征方法与氢氧滴定相比,不仅可以得到贵金属原子表面分散度,还可以更直观、全面评价贵金属在载体上的分散状态,尤其对不适合使用氢氧滴定法及常规TEM衬度成像难以区分的金属纳米粒子和载体的体系,具有较高应用价值。Noble metal dispersion performance of Pd/Al2O3 catalyst were characterized by high angle annular dark field（HAADF） coupled with ultrathin sections. The average particle size, particle size distribution, spatial particle number density and surface atomdispersionwere presented to measure quantitatively dispersion property of noble metal. The experimental results show that the large area thin area with 30 - 40 nm thickness can easily be got to acquire HADDF Images, which are used to calculate the average particle size, particle size distribution, spatial particle number density and surface atom dispersion of Pd/Al2O3 catalyst. Compare with HOT method, the combination of characterization methods can not only present surface atom dispersion but estimate directly comprehensive dispersion state of Pd supported on Al2 O3, is appropriate for supported noble metal catalysts, especially for the weak TEM contrast between carrier and metal nano-paticles.

关 键 词：超薄切片 高角环形暗场像 贵金属催化剂 分散性 

分 类 号：TQ426.95[化学工程]