SEM-EDS研究NiMo/Al_2O_3催化剂失活机理  

SEM-EDS study on the deactivation mechanism of NiMo/Al_2O_3 catalyst

作　　者：王海涛[1] 肖天存[1] 苏继新[1] 鹿玉理[1] 张孔远[2] 郑绍宽[2] 

机构地区：[1]山东大学环境工程系,济南250100 [2]齐鲁石化公司研究院,山东淄博255400

出　　处：《电子显微学报》1999年第6期624-629,共6页Journal of Chinese Electron Microscopy Society

基　　金：山东省优秀中青年科学家科研奖励基金

摘　　要：收集了炼油厂失活的加氢精制镍钼催化剂，用扫描电子显微镜观察反应前后样品的形貌变化及微区成分分析，对催化剂不同部位的组成进行剖析。结果表明：催化剂外层沉积了大量磷、铁、硫及少量钾和钙等物质，这些呈鱼鳞状的物质覆盖了催化剂上的镍钼活性中心，并覆盖了催化剂外表面，使吸附的沥青质无法与活性中心接触，从而导致催化剂失活。从催化剂外层向内层，磷的含量迅速下降，而铁、钙和钾等元素主要分布在催化剂的外表面，硫以硫酸根和硫化物的形式存在。热处理和水洗方式不能恢复催化剂活性中心，但通过热处理可除去积炭。Spent NiMo/Al\-2O\-3 catalysts for hydrodesulfurization (HDS) fo heavy residuum were collected and treated under different conditions. SEM was employed to observe the changes of the morphologies,while EDS was used to analyze the composition at various position of the single catalyst particle. The results showed that the outer layer of the spent catalyst was covered by a large amount of phosphorus, iron and sulfur, and a little potassium and calcium. The compounds of these elements were in fish\|scale shape,which pack the surface and shield the active centers of the catalysts,separate the reactants of residuum from the active center, and thus result in the deactivation of the catalysts. From the outer layer to the inner layer of the catalyst, phosphorus content decreases rapidly, while iron, calcium and potassium distribute mainly in the outer layer of the spent catalyst, sulfur is in the form of S\+\{2-\} and SO\+\{2-\}\-4. Thermal treatment of the spent catalyst can only remove the deposited carbon, but can not remove the phosphorus, iron and other metals. Washing and scrubbing can remove some sulfate. For the catalysts deactivated by large deposit of carbon, thermal treatment and washing can not fully recover the active center of the spent catalyst.

关 键 词：加氢催化剂 失活 SEM-EDS 

分 类 号：O643.36[理学—物理化学]