title: Combined UHV/high-pressure catalysis setup for depth-resolved near-surface spectroscopic characterization and catalytic testing of model catalysts.
abstract: An ultra-high vacuum (UHV) setup for "real" and "inverse" model catalyst preparation, depth-resolved near-surface spectroscopic characterization, and quantification of catalytic activity and selectivity under technologically relevant conditions is described. Due to the all-quartz reactor attached directly to the UHV-chamber, transfer of the catalyst for in situ testing without intermediate contact to the ambient is possible. The design of the UHV-compatible re-circulating batch reactor setup allows the study of reaction kinetics under close to technically relevant catalytic conditions up to 1273 K without contact to metallic surfaces except those of the catalyst itself. With the attached differentially pumped exchangeable evaporators and the quartz-microbalance thickness monitoring equipment, a reproducible, versatile, and standardised sample preparation is possible. For three-dimensional near-surface sample characterization, the system is equipped with a hemispherical analyser for X-ray photoelectron spectroscopy (XPS), electron-beam or X-ray-excited Auger-electron spectroscopy, and low-energy ion scattering measurements. Due the dedicated geometry of the X-ray gun (54.7°, "magic angle") and the rotatable sample holder, depth analysis by angle-resolved XPS measurements can be performed. Thus, by the combination of characterisation methods with different information depths, a detailed three-dimensional picture of the electronic and geometric structure of the model catalyst can be obtained. To demonstrate the capability of the described system, comparative results for depth-resolved sample characterization and catalytic testing in methanol steam reforming on PdGa and PdZn near-surface intermetallic phases are shown.
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria.
authors.forename: Lukas
authors.initials: L
authors.lastname: Mayr
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria.
authors.forename: Raffael
authors.initials: R
authors.lastname: Rameshan
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Klötzer
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria.
authors.forename: Simon
authors.initials: S
authors.lastname: Penner
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Rameshan