New DRIFTS-Cell Design for the Simultaneous Acquisition of Spectroscopic and Kinetic Data

A new design for a DRIFTS cell for in-situ studies in heterogeneous catalysis is presented, which allows for improved reaction control (i.e., gas flow, temperature, minimized background conversion) and for precise kinetic measurements. Specifically, the very low background activity of the cell itself for CO and H2 oxidation makes it possible to study the preferential CO oxidation in H2-rich gases (PROX) at relevant reaction temperatures (150-350°C) and reactant concentrations (≤ 1 kPa CO and O2). Comparison with results obtained in a quartz tube reactor shows excellent agreement with the reaction rates obtained in the DRIFTS cell. The improved performance of the new DRIFTS cell design is demonstrated by examining the influence of CO2 on the PROX reaction over a Au/Fe2O3 catalyst. The addition of CO2 to idealized reformate (varying CO and O2 partial pressures, 75 kPa H2, balance N2) significantly reduces both, the CO oxidation rate and the selectivity of the PROX reaction on Au/α-Fe2O3, and strongly affects the frequency of the C-O stretch vibration of adsorbed CO due to CO2 coadsorption. Index Headings: In-situ DRIFTS, FTIR Cell Design, Gold Catalysts, Au/Fe2O3, Selective CO Oxidation, PROX Running title: New DRIFTS-Cell Design Submitted to Appl. Spectr.: 08.01.2001 *: pres. address: Laboratory for Technical Chemistry, Swiss Federal Institute of Technology; ETH-Zentrum; CH-8092 Zürich, Switzerland; e-mail: [email protected] †: pres. address: GM Global R&D, Global Alternative Propulsion Center, 10 Carriage St., Honeoye Falls, NY 14472-0603, USA Schubert et al. New DRIFTS-Cell Design