de Smit, Emiel; Swart, Ingmar; Creemer, J. Fredrik; Hoveling, Gerard H.; Gilles, Mary K.; Tyliszczak, Tolek; Kooyman, Patricia J.; Zandbergen, Henny W.; Morin, Cynthia; Weckhuysen, Bert M.; de Groot, Frank M. F.

Nature (London, United Kingdom) (2008), 456(7219), 222-225 CODEN: NATUAS; ISSN: 0028-0836. English.

The modern chem. industry uses heterogeneous catalysts in almost every production process. They commonly consist of nanometer-size active components (typically metals or metal oxides) dispersed on a high-surface-area solid support, with performance depending on the catalysts' nanometer-size features and on interactions involving the active components, the support and the reactant and product mols. To gain insight into the mechanisms of heterogeneous catalysts, which could guide the design of improved or novel catalysts, it is thus necessary to have a detailed characterization of the physicochem. composition of heterogeneous catalysts in their working state at the nanometer scale. Scanning probe microscopy methods were used to study inorg. catalyst phases at sub-nanometer resolution, but detailed chem. information of the materials in their working state is often difficult to obtain. By contrast, optical microspectroscopic approaches offer much flexibility for in situ chem. characterization; however, this comes at the expense of limited spatial resolution A recent development promising high spatial resolution and chem. characterization capabilities is scanning transmission x-ray microscopy, which was used in a proof-of-principle study to characterize a solid catalyst. When adapting a nanoreactor specially designed for high-resolution electron microscopy, scanning transmission x-ray microscopy can be used at atmospheric pressure and up to 350.degree. to monitor in situ phase changes in a complex iron-based Fischer-Tropsch catalyst and the nature and location of carbon species produced. The authors expect that the system, which is capable of operating up to 500.degree., will open new opportunities for nanometer-resolution imaging of a range of important chem. processes taking place on solids in gaseous or liquid environments.