Scanning Tunneling Microscopic Studies on Model Molybdenum Sulfide Catalysts

这是一个拓扑和电子的调查， 促进和未促进二硫化钼的行为 使用最先进的扫描隧道效应的晶体 扫描隧道显微镜（STM）和扫描隧道光谱（STS） 技术. 测量是在双真空下进行的 在大气条件下， 催化剂表面。 目标是：（1）使用 扫描隧道显微镜（STM）表征二硫化钼单晶 在溅射之前和之后的表面，并将其与 石墨上的硫化钼（100）和二硫化钼; (2)研究钴对形貌的影响， 二硫化钼的电子结构 （3）研究吸附和解离 探针分子如噻吩的特性， 二噻吩，和在二硫化钼上的苯并噻吩， 钴促进的二硫化钼和二硫化钼 （4）在石墨上进行硫化处理， 钼（100）和石墨上的氧化钼。 数据 根据反应位点的性质进行解释， 加氢脱硫（HDS）催化反应机理。 这项研究涉及一种新的电池的应用， 技术（隧道显微镜）的经典问题 （加氢硫化）对两者都有潜在的益处。 尽管在过去的两年里，HDS几乎没有进展， 几十年来，环境压力迫使它 又是兴趣的前沿。 虽然被广泛使用， 过程仍然知之甚少，甚至是渐进的 改进可能会产生重大影响。

This an investigation of the topological and electronic behavior of promoted and unpromoted molybdenum disulfide crystals using state-of-the-art scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS) techniques. Measurements are made both under ultrahigh vacuum and under atmospheric conditions in order to follow changes in the catalyst surface. The goals of the effort are (1) using STM, to characterize the molybdenum disulfide single-crystal surface before and after sputtering, and to contrast this to sulfided molybdenum(100) and molybdenum disulfide on graphite; (2) to investigate the effect of cobalt on the morphology and on the electronic structure of molybdenum disulfide under various loadings; (3) to study the adsorption and dissociation characteristics of probe molecules such as thiophene, dithiophene, and benzothiophene on molybdenum disulfide, cobalt-promoted molybdenum disulfide, and molybdenum disulfide on graphite; and (4) to follow the sulfidation process of molybdenum(100) and molybdenum oxide on graphite. The data are interpreted in terms of nature of reaction sites and reaction mechanisms in hydrodesulfurization (HDS) catalysis. This study involves the application of a new battery of techniques (tunnelling microscopy) to a classical problem (hydrosulfurization) with potential benefits for both. Although there has been little advance in HDS in the last two decades, environmental pressures are forcing it to the forefront of interest again. Although widely practiced, the process is still poorly understood, and even incremental improvements could have a major impact.