N. Köpfle, L. Mayr, D. Schmidmair, J. Bernardi, A. Knop-Gericke, M. Hävecker, B. Klötzer, S. Penner:
"A Comparative Discussion of the Catalytic Activity and CO2-Selectivity of Cu-Zr and Pd-Zr (Intermetallic) Compounds in Methanol Steam Reforming";
The activation and catalytic performance of two representative Zr-containing intermetallic
systems, namely Cu-Zr and Pd-Zr, have been comparatively studied operando using methanol
steam reforming (MSR) as test reaction. Using an inverse surface science and bulk model catalyst
approach, we monitored the transition of the initial metal/intermetallic compound structures into
the eventual active and CO2-selective states upon contact to the methanol steam reforming mixture.
For Cu-Zr, selected nominal stoichiometries ranging from Cu:Zr = 9:2 over 2:1 to 1:2 have been
prepared by mixing the respective amounts of metallic Cu and Zr to yield different Cu-Zr bulk phases
as initial catalyst structures. In addition, the methanol steam reforming performance of two Pd-Zr
systems, that is, a bulk system with a nominal Pd:Zr = 2:1 stoichiometry and an inverse model system
consisting of CVD-grown ZrOxHy layers on a polycrystalline Pd foil, has been comparatively assessed.
While the CO2-selectivity and the overall catalytic performance of the Cu-Zr system is promising due
to operando formation of a catalytically beneficial Cu-ZrO2 interface, the case for Pd-Zr is different.
For both Pd-Zr systems, the low-temperature coking tendency, the high water-activation temperature
and the CO2-selectivity spoiling inverse WGS reaction limit the use of the Pd-Zr systems for selective
MSR applications, although alloying of Pd with Zr opens water activation channels to increase the
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