Imaging Industrial-Type Catalysts

By using a novel electron microscopy method, an international team has recorded images of industrial-type nanostructured molybdenum disulfide catalyst particles with element specificity and single-atom resolution (Angew. Chem. Int. Ed. 2010, 49, 2708). Previous studies that yielded atomic resolution details of MoS₂, a hydrotreating catalyst used to strip sulfur from petroleum, typically focused on model single-crystal-supported specimens that were prepared under pristine vacuum conditions. In contrast, the current study—led by Stig Helveg of Danish catalyst manufacturer Haldor Topsøe, Christian Kisielowski of Lawrence Berkeley National Laboratory, and coworkers—focuses on MoS₂ samples synthesized on graphitic carbon powder via the same methods used to manufacture catalysts for oil refineries. The researchers analyzed the samples with a recently developed transmission electron microscopy technique that enabled them to distinguish between one- and two-layer-thick regions of the particles and determine the chemical identity of the atoms throughout those regions. The results, which the team notes are in “excellent agreement” with computer simulations, could help establish new relationships between the catalyst’s function and atomic structure and could offer possibilities for improving catalyst formulations, they say.