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SLAC National Accelerator Laboratory

Fischer-Tropsch Catalyst Nanoscale Chemistry under Realistic Working Conditions
SSRL Science Summary - November 2012

Snapshot of 3D elemental mapping (see Rock on Fire)
Olefins are the basic building blocks for many products from the petrochemical industry and are currently produced by steam cracking of naphtha or ethane, but increasing oil and gas prices are driving the industry toward producing olefins from syngas derived from cheaper feedstocks via the Fischer-Tropsch process instead. A team of scientists used full-field Transmission hard X-ray Microscopy (TXM) and a special reactor designed and built at SSRL and installed on SSRL Beam Line 6-2 to learn more about the catalyst at the heart of the Fischer-Tropsch-to-Olefins (FTO) process.

The FTO process commonly uses an iron-based catalyst, to which promoters can be added to improve catalytic activity and affect selectivity toward light olefins. The active sites are thought to be located on metal nanoparticles, but their exact chemical nature is still under debate. Using the customized reactor and recent advances in in situ spectroscopic techniques, scientists from Utrecht University and The Dow Chemical Company and Fondazione Bruno Kessler, in close collaboration with SSRL, were able to follow a single nanoscale catalytic particle, a bulk iron oxide promoted with titanium, zinc and potassium oxides, during activation and under Fischer-Tropsch reaction conditions.

Their results show that recent advances in TXM combined with their specially designed in situ spectroscopy reactor enable the study of dynamic changes of a single catalyst particle under high pressure (10-30 bar) and temperature (350-500 °C). By following single-pixel chemistry of a working catalyst at nm-scale resolution, they successfully correlated catalyst reaction chemistry with specific chemical forms within the starting particle. This type of spatially resolved chemical information can inform synthesis protocols for FTO and other catalysts for optimized activity.


Primary Citation

I. Gonzalez-Jimenez, K. Cats, T. Davidian, M. Ruitenbeek, F. Meirer, Y. Liu, J. Nelson, J.C. Andrews, P. Pianetta, F.M.F. de Groot, B.M. Weckhuysen (2012) Hard X-Ray Nanotomography of Catalytic Solids at Work, Angew. Chem. Int. Ed. v51:11986-11990.
[DOI: 10.1002/ anie.201204930]

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Joy C. Andrews (SSRL) and Bert M. Weckhuysen (Utrecht)

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