ACS Publications
Due to its peculiar properties and strong interaction with noble metals, ceria is widely used as a catalyst support for numerous applications. In this work, morphologically pure and highly crystalline ceria nanocubes and nanorods were prepared to systematically investigate both the impact of the support morphology and Pd–Pt interaction degree on the noble metal-support interplay during CO oxidation. By using a constant surface noble metal concentration, the same probability for cluster/nanoparticle formation or noble metal redispersion during catalyst pretreatment and under reaction conditions was ensured. This novel approach allows for highlighting the impact of the support morphology on the catalyst dynamics and reveals different activity trends compared to what was previously reported for monometallic Pd- or Pt-catalysts supported on CeO2. In particular, complementary ex situ and in situ/operando characterization tools combined with catalytic tests uncovered that by tuning the morphology and surface characteristics of ceria, the clustering and redispersion of the deposited noble metals in different atmospheres (e.g., oxidizing/reducing) can be controlled. The initial state and corresponding catalyst dynamics were thoroughly probed, showing that by depositing Pt and Pd on CeO2-nanocubes, a balanced noble metal–support interaction is obtained that promotes the formation and retention of small and active noble metal clusters, regardless of the initial Pd–Pt interaction. In contrast, a high number of surface defects, as evidenced by Raman spectroscopy for CeO2-nanorods, fosters the formation of highly dispersed species with a decreased low-temperature activity. Pd and Pt species with minimal mutual interaction performed better during CO oxidation, while the presence of alloyed particles on ceria prevented rapid noble metal redispersion and thus catalyst deactivation. Based on a rational adjustment of the noble metal–support interaction, the findings of this study are expected to contribute to the future development of NM/CeO2-based catalysts containing the desired active sites, i.e., highly dispersed species or nanoparticles.
For details
Influence of the CeO₂ Morphology and Initial Pd–Pt Interaction Degree on Catalyst Activity and Stability
Andrea De Giacinto a,b, Paolo Dolcet a,b, Di Wang c,d, Joachim Czechowsky a, Carina B. Maliakkal c, Christian Kübel c,d, Silke Behrens e, Jan-Dierk Grunwaldt a,e, Silvia Gross a,b, Maria Casapu a
a) Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), Engesserstrasse 18, 76131 Karlsruhe, Germany;
b) Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, 35131 Padova, Italy
c) Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
d) Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
e) Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
DOI: https://pubs.acs.org/doi/full/10.1021/acs.jpcc.5c04366
