The Complex Nanostructure of an Ammonia Synthesis Catalyst

A complex nano structured catalyst for ammonia synthesis consists of ruthenium nanoclusters dispersed on a boron nitride support (Ru/BN) with barium added as a promoter (JJ). It was observed that the introduction of barium promoters results in an increase of the catalytic activity by 2—3 orders of magnitude. The multi-phase catalyst was first investigated by means of conventional HRTEM, but this technique did not succeed in identifying a barium-rich phase (34). It was even difficult to determine how the catalyst could be active, because the ruthenium clusters were encapsulated by layers of the boron nitride support. By HRTEM imaging of the catalyst during exposure to ammonia synthesis conditions, it was found that the 

On the basis of these results, the increased activity of the promoted catalyst was attributed to a two-dimensional barium-oxygen overlayer on the ruthenium nanocrystals, located in the vicinity of the crystal edges (Bs-type sites). The ability to 

Gas-Induced Shape Changes in Cu/ZnO-Containing Methanol Synthesis 

The microscopy results characterizing the Cu/ZnO catalyst are in accord with EXAFS data representing the dynamic morphology changes (39-41), and they also provide an important additional insight On the basis of the lattice-resolved images, the nature of the exposed facets of the projected copper nanoclusters and the epitaxial relationship between the copper and ZnO can be identified. The majority of the copper nanocrystals appear to be in contact with the ZnO support with their (1 1 1) facets, as was also observed for copper particles prepared by vapor 

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