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Title: Adding diffuse reflectance infrared Fourier transform spectroscopy capability to extended x-ray-absorption fine structure in a new cell to study solid catalysts in combination with a modulation approach

We describe a novel cell used to combine in situ transmission X-ray absorption spectroscopy (XAS) with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in a single experiment. The novelty of the cell design compared to current examples is that both radiations are passed through an X-ray and IR transparent window in direct contact with the sample. This innovative geometry also offers a wide surface for IR collection. In order to avoid interference from the crystalline IR transparent materials (e.g., CaF{sub 2}, MgF{sub 2}, diamond) a 500 μm carbon filled hole is laser drilled in the center of a CaF{sub 2} window. The cell is designed to represent a plug flow reactor, has reduced dead volume in order to allow for fast exchange of gases and is therefore suitable for experiments under fast transients, e.g., according to the concentration modulation approach. High quality time-resolved XAS and DRIFTS data of a 2 wt.% Pt/Al{sub 2}O{sub 3} catalyst are obtained in concentration modulation experiments where CO (or H{sub 2}) pulses are alternated to O{sub 2} pulses at 150 °C. We show that additional information can be obtained on the Pt redox dynamic under working conditions thanks to the improved sensitivity given by the modulationmore » approach followed by Phase Sensitive Detection (PSD) analysis. It is anticipated that the design of the novel cell is likely suitable for a number of other in situ spectroscopic and diffraction methods.« less
Authors:
 [1] ; ; ; ;  [2]
  1. Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi 19, I-20133 Milano, Italy and Empa, Swiss Federal Laboratories for Materials Science and Technology, Lab. for Solid State Chemistry and Catalysis, Ueberlandstrasse 129, CH-8600 Dübendorf (Switzerland)
  2. Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)
Publication Date:
OSTI Identifier:
22308685
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ABSORPTION SPECTROSCOPY; ABUNDANCE; ALUMINIUM OXIDES; CARBON MONOXIDE; CATALYSTS; CRYSTALS; DIAMONDS; DIFFRACTION METHODS; FINE STRUCTURE; FOURIER TRANSFORM SPECTROMETERS; GASES; HYDROGEN; INFRARED RADIATION; MAGNESIUM FLUORIDES; OXYGEN; PULSES; SENSITIVITY; TIME RESOLUTION; WORKING CONDITIONS; X-RAY SPECTROSCOPY