负载的钼催化剂表面结构的研究  

Studies on Surface Structures of Supported Molybdenum Catalysts by LRS and XPS

作　　者：陆伟杰 伏义路[1] 许存义[1] 黄志刚[1] 吴建新[1] 范立 

机构地区：[1]中国科学技术大学

出　　处：《Chinese Journal of Chemical Physics》1989年第3期222-232,共11页化学物理学报（英文）

基　　金：国家自然科学基金

摘　　要：本文应用激光拉曼光谱和X光光电子能谱技术,研究了在γ-Al_2O_3、ZrO_2、CeO_2和La_2O_3几种载体上,氧化态和硫化态钼催化剂的表面结构。在氧化态样品上,MoO_3基本上是单层分布的,但钼的存在形态在不同载体上差别较大,表现出较强的载体效应。讨论了催化剂从氧化态到硫化态转化过程中的结构变化,即钼首先由+6价还原成+4价,然后发生一系列氧硫交换过程,逐步被硫化。并讨论了暴露空气后对硫化态催化剂结构的影响。Laser Raman spectra of oxidized and sulfided molybdenum catalysts supported on γ-Al_2O_3, ZrO_2, CeO_2, and La_2O_3 were measured. According to MoO_3 monolayer model and when MoO_3 loading was equal to the monolayer saturated capacity on γ-Al_2O_3 catalyst, tetrahedral and octahedral coordinated Mo, bulk MoO_3 and molybdate were formed. On ZrO_2, two kinds of coordinated Mo were determined. Only octahedral Mo on DeO_2 and only tetrahedral Mo on La_2O_3 were observed. A strong support effect appeared. In the sulfided samples, surface oxysulfide molybdnum and little MoS_2 microcrystal on the catalysts were formed. The sulfidation process of Mo / ZrO_2 and Mo / CeO_2 was studied by XPS. Under the weaker sulfidation condition (300C, 20min), the most of Mo^(+6) were reduced to Mo^(+4). The structure of highly dispersed Mo was destroied gradually and sulfur loading was increased step by step with sulfiding. The surface structures of oxidized and sulfided state were discussed ac- cording to the results of LRS and XPS.

关 键 词：钼催化剂 表面结构 

分 类 号：TQ426.81[化学工程]