[Zurück]

K. Ploner, M. Watschinger, P. Kheyrollahi Nezhad, T. Götsch, L. Schlicker, E.M. Köck, A. Gurlo, A. Gili, A. Doran, L. Zhang, N. Köwitsch, M. Armbrüster, S. Vanicek, W. Wallisch, C. Thurner, B. Klötzer, S. Penner:
"Mechanistic insights into the catalytic methanol steam reforming performance of Cu/ZrO2 catalysts by in situ and operando studies";
Journal of Catalysis, 391 (2020), S. 497 - 512.

We assessed the catalytic properties of the Cu/ZrO2 interface in methanol and formaldehyde steam
reforming (MSR and FSR) on powder catalysts by using a comparative approach with respect to the influence
of the ZrO2 polymorph support structure (monoclinic (m-)ZrO2 vs. tetragonal (t-)ZrO2), its synthesis
routine and the choice of the precursor material on the CO2 selectivity. Our studies reveal that ZrO2 exhibits
a pronounced versatility as a support material and its catalytic properties depend most strongly on
its surface properties governed by its synthesis, especially by the choice of the Zr precursor. The way of
combining the support with copper introduces an additional layer of complexity, but its influence on the
MSR performance is limited to a modification of the conditions provided by the ZrO2 support. Exploiting
the comparative approach regarding the Cu-ZrO2 catalysts in FSR and MSR - including the pure support
materials - in combination with in situ Fourier transform infrared (FT-IR) spectroscopy shows that the CO
observed in MSR on Cu/m-ZrO2 can be attributed to a spillover of formaldehyde to the support. Side reactions
of m-ZrO2 are suppressed at lower temperatures due to its lack of highly reactive sites, resulting in a
CO2-selective MSR performance. In Cu/t-ZrO2, however, the amount of CO is higher and a combination of
a formaldehyde spillover to the support and a Cu-ZrO2 phase boundary yielding CO leads to the lower CO2
selectivity of these samples. An elevated number of defects and reactive Lewis acidic and Brønsted basic
centers of t-ZrO2 explains this increased activity towards side reactions in contrast to Cu/m-ZrO2
catalysts.

http://dx.doi.org/10.1016/j.jcat.2020.09.018