skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Small-volume, ultrahigh-vacuum-compatible high-pressure reaction cell for combined kinetic and in situ IR spectroscopic measurements on planar model catalysts

Abstract

We describe the design and performance of a high-pressure reaction cell for simultaneous kinetic and in situ infrared reflection (IR) spectroscopic measurements on model catalysts at elevated pressures, between 10{sup -3} and 10{sup 3} mbars, which can be operated both as batch reactor and as flow reactor with defined gas flow. The cell is attached to an ultrahigh-vacuum (UHV) system, which is used for sample preparation and also contains facilities for sample characterization. Specific for this design is the combination of a small cell volume, which allows kinetic measurements with high sensitivity under batch or continuous flow conditions, the complete isolation of the cell from the UHV part during UHV measurements, continuous temperature control during both UHV and high-pressure operation, and rapid transfer between UHV and high-pressure stage. Gas dosing is performed by a designed gas-handling system, which allows operation as flow reactor with calibrated gas flows at adjustable pressures. To study the kinetics of reactions on the model catalysts, a quadrupole mass spectrometer is connected to the high-pressure cell. IR measurements are possible in situ by polarization-modulation infrared reflection-absorption spectroscopy, which also allows measurements at elevated pressures. The performance of the setup is demonstrated by test measurements on themore » kinetics for CO oxidation and the CO adsorption on a Au/TiO{sub 2}/Ru(0001) model catalyst film at 1-50 mbar total pressure.« less

Authors:
; ; ; ;  [1]
  1. Department Surface Chemistry and Catalysis, University of Ulm, D-89069 Ulm (Germany)
Publication Date:
OSTI Identifier:
20778487
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 76; Journal Issue: 12; Other Information: DOI: 10.1063/1.2140449; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; ADSORPTION; CATALYSTS; CHEMICAL REACTORS; DESIGN; GAS FLOW; GOLD; MASS SPECTROMETERS; MODULATION; OPERATION; OXIDATION; PERFORMANCE; POLARIZATION; REFLECTION; RUTHENIUM; SAMPLE PREPARATION; SENSITIVITY; TEMPERATURE CONTROL; TITANIUM OXIDES

Citation Formats

Zhao, Z., Diemant, T., Haering, T., Rauscher, H., and Behm, R.J. Small-volume, ultrahigh-vacuum-compatible high-pressure reaction cell for combined kinetic and in situ IR spectroscopic measurements on planar model catalysts. United States: N. p., 2005. Web. doi:10.1063/1.2140449.
Zhao, Z., Diemant, T., Haering, T., Rauscher, H., & Behm, R.J. Small-volume, ultrahigh-vacuum-compatible high-pressure reaction cell for combined kinetic and in situ IR spectroscopic measurements on planar model catalysts. United States. doi:10.1063/1.2140449.
Zhao, Z., Diemant, T., Haering, T., Rauscher, H., and Behm, R.J. Thu . "Small-volume, ultrahigh-vacuum-compatible high-pressure reaction cell for combined kinetic and in situ IR spectroscopic measurements on planar model catalysts". United States. doi:10.1063/1.2140449.
@article{osti_20778487,
title = {Small-volume, ultrahigh-vacuum-compatible high-pressure reaction cell for combined kinetic and in situ IR spectroscopic measurements on planar model catalysts},
author = {Zhao, Z. and Diemant, T. and Haering, T. and Rauscher, H. and Behm, R.J.},
abstractNote = {We describe the design and performance of a high-pressure reaction cell for simultaneous kinetic and in situ infrared reflection (IR) spectroscopic measurements on model catalysts at elevated pressures, between 10{sup -3} and 10{sup 3} mbars, which can be operated both as batch reactor and as flow reactor with defined gas flow. The cell is attached to an ultrahigh-vacuum (UHV) system, which is used for sample preparation and also contains facilities for sample characterization. Specific for this design is the combination of a small cell volume, which allows kinetic measurements with high sensitivity under batch or continuous flow conditions, the complete isolation of the cell from the UHV part during UHV measurements, continuous temperature control during both UHV and high-pressure operation, and rapid transfer between UHV and high-pressure stage. Gas dosing is performed by a designed gas-handling system, which allows operation as flow reactor with calibrated gas flows at adjustable pressures. To study the kinetics of reactions on the model catalysts, a quadrupole mass spectrometer is connected to the high-pressure cell. IR measurements are possible in situ by polarization-modulation infrared reflection-absorption spectroscopy, which also allows measurements at elevated pressures. The performance of the setup is demonstrated by test measurements on the kinetics for CO oxidation and the CO adsorption on a Au/TiO{sub 2}/Ru(0001) model catalyst film at 1-50 mbar total pressure.},
doi = {10.1063/1.2140449},
journal = {Review of Scientific Instruments},
number = 12,
volume = 76,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}
  • No abstract prepared.
  • A small-volume reaction cell for catalytic or photocatalytic testing of solid materials at pressures up to 1000 Torr has been coupled to a surface-science setup used for standard sample preparation and characterization under ultrahigh vacuum (UHV). The reactor and sample holder designs allow easy sample transfer from/to the UHV chamber, and investigation of both planar and small amounts of powder catalysts under the same conditions. The sample is heated with an infrared laser beam and its temperature is measured with a compact pyrometer. Combined in a regulation loop, this system ensures fast and accurate temperature control as well as cleanmore » heating. The reaction products are automatically sampled and analyzed by mass spectrometry and/or gas chromatography (GC). Unlike previous systems, our GC apparatus does not use a recirculation loop and allows working in clean conditions at pressures as low as 1 Torr while detecting partial pressures smaller than 10{sup −4} Torr. The efficiency and versatility of the reactor are demonstrated in the study of two catalytic systems: butadiene hydrogenation on Pd(100) and CO oxidation over an AuRh/TiO{sub 2} powder catalyst.« less
  • A bakeable, ultrahigh-vacuum compatible, retractable four-point resistance probe has been constructed to make in situ measurements of superconductivity in ultrathin films. A bellows actuation mechanism allows the very compact contacting mechanism to be withdrawn from the substrate area for cleaning and characterization of the substrate surface, then returned for film resistance measurements. The device has been used to make contact to Pb films less than 10 A thick deposited on high-resistivity Si substrates, which require a cleaning step that would be destructive to permanent or predeposited contacts.
  • A kinetics study of the CO + NO reaction over Pd has been carried out using single-crystal, model planar-supported, and conventional high-surface-area Pd/Al{sub 2}O{sub 3} catalysts. A pronounced structure sensitivity is evident that results in a rate enhancement over the Pd(111) single crystal relative to the more open (100) and (110) faces, and for larger supported particles relative to smaller ones. Temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) data indicate that the Pd(100) face is more active for NO dissociation and atomic N stabilization than the close-packed (111) plane. Similarly, TPD results show that smaller particles in the modelmore » supported catalysts are more active for atomic N formation and stabilization. The inverse correlation between reaction activity and N, formation and stabilization suggests that an inactive atomic N species plays a role in determining the reaction rate. 33 refs., 11 figs., 1 tab.« less
  • 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 andmore » 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.« less