Nanoscale Chemical Imaging of Catalysts at Work

13 November 2008

Chemists at Utrecht University (The Netherlands) have developed a new method using X-ray microscopy to observe catalysts in action. A report on their work is published in the 13 November edition of the journal Nature.

Gaining insight into the mechanisms of heterogeneous catalysts could lead to improved or novel catalysts. So far, scanning probe microscopy methods have been used to study inorganic catalyst phases at sub-nanometer resolution, but detailed chemical information of the materials in their working state is often difficult to obtain. Optical microspectroscopic approaches offer more flexibility for in situ chemical characterization; however, this comes at the expense of limited spatial resolution.

The researchers at Utrecht, in collaboration with the Delft University of Technology (The Netherlands) and the Lawrence Berkeley National Laboratory (USA), used scanning transmission X-ray microscopy to provide both high spatial resolution and chemical characterization capability. In a proof-of-principle study, they used the technique to characterize a solid Fischer-Tropsch catalyst.

This enabled them to see chemical state of the individual particles in the working catalyst. The researchers believe the X-ray microscope used may make other nano-level processes visible, such as hydrogen storage and the distribution of medical nanoparticles in living cells.

Separately, a team of scientists at Berkeley Laboratory recently reported on the use of a state-of-the-art spectroscopy system to observe bi-metallic nanoparticle catalysts changing their composition in the presence of different reactants. Until now, scientists have had to rely on snapshots of catalysts taken before and after a reaction. A paper describing that work was published online 9 October in the journal Science. (Earlier post.)

Resources

• E de Smit et al. (2008) Nanoscale chemical imaging of a working catalyst by scanning transmission X-ray microscopy Nature doi: 10.1038/nature07516