Combined TPRx, in situ GISAXS and GIXAS studies of model semiconductor-supported platinum catalysts in the hydrogenation of ethene

Sonja A. Wyrzgol; Susanne Schäfer; Sungsik Lee; Byeongdu Lee; Marcel Di Vece; Xuebing Li; Sönke Seifert; Randall E. Winans; Martin Stutzmann; Johannes A. Lercher; Stefan Vajda

doi:10.1039/B926493K

Combined TPRx, in situGISAXS and GIXAS studies of model semiconductor-supported platinumcatalysts in the hydrogenation of ethene

Sonja A. Wyrzgol,^a Susanne Schäfer,^b Sungsik Lee,†^c Byeongdu Lee,^d Marcel Di Vece,^e Xuebing Li,^a Sönke Seifert,^d Randall E. Winans,^d Martin Stutzmann,^b Johannes A. Lercher*^a and Stefan Vajda ‡*^cef

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* Corresponding authors

^a Department of Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstr. 4, D-85747 Garching, Germany
E-mail: johannes.lercher@ch.tum.de

^b Experimental Semiconductor Physics 2, Walter Schottky Institute and Catalysis Research Center, Technische Universität München, Am Coulombwall 3, D-85747 Garching, Germany

^c Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, USA
E-mail: vajda@anl.gov

^d X-Ray Sciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, USA

^e Department of Chemical Engineering, Yale University, 9 Hillhouse Avenue, New Haven, USA

^f Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, USA

Abstract

The preparation, characterization and catalytic reactivity of a GaN supported Pt catalyst in the hydrogenation of ethene are presented in this feature article, highlighting the use of in situ characterization of the material properties during sample handling and catalysis by combining temperature programmed reaction with in situ grazing incidence small-angle X-ray scattering and X-ray absorption spectroscopy. The catalysts are found to be sintering resistant at elevated temperatures as well as during reduction and hydrogenation reactions. In contrast to Pt particles of approximately 7 nm diameter, smaller particles of 1.8 nm in size are found to dynamically adapt their shape and oxidation state to the changes in the reaction environment. These smaller Pt particles also showed an initial deactivation in ethene hydrogenation, which is paralleled by the change in the particle shape. The subtle temperature-dependent X-ray absorbance of the 1.8 nm sized Pt particles indicates that subtle variations in the electronic structure induced by the state of reduction by electron tunnelling over the Schottky barrier between the Pt particles and the GaN support can be monitored.

This article is part of the themed collection: Recent developments in X-ray absorption spectroscopy

Physical Chemistry Chemical Physics

Combined TPRx, in situGISAXS and GIXAS studies of model semiconductor-supported platinumcatalysts in the hydrogenation of ethene

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