Oxidative Thermal Sintering and Redispersion of Rh Nanoparticles on Supports with High Oxygen Ion Lability
Grammatiki Goula,
Georgia Botzolaki,
Amin Osatiashtiani,
Christopher M. A. Parlett,
Georgios Kyriakou,
Richard M. Lambert,
Ioannis V. Yentekakis
Affiliations
Grammatiki Goula
Laboratory of Physical Chemistry & Chemical Processes (<uri>www.pccplab.tuc.gr</uri>), School of Environmental Engineering, Technical University of Crete, GR-73100 Chania, Greece
Georgia Botzolaki
Laboratory of Physical Chemistry & Chemical Processes (<uri>www.pccplab.tuc.gr</uri>), School of Environmental Engineering, Technical University of Crete, GR-73100 Chania, Greece
Amin Osatiashtiani
European Bioenergy Research Institute, Aston University, Aston Triangle, Birmingham B4 7ET, UK
Christopher M. A. Parlett
The School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, UK
Georgios Kyriakou
European Bioenergy Research Institute, Aston University, Aston Triangle, Birmingham B4 7ET, UK
Richard M. Lambert
Department of Chemistry, Cambridge University, Cambridge CB2 1EW, UK
Ioannis V. Yentekakis
Laboratory of Physical Chemistry & Chemical Processes (<uri>www.pccplab.tuc.gr</uri>), School of Environmental Engineering, Technical University of Crete, GR-73100 Chania, Greece
The thermal sintering under oxidative conditions of Rh nanoparticles supported on oxides characterized by very different oxygen storage capacities (OSC) and labilities was studied at 750 and 850 °C. Under sintering conditions, significant particle growth occurred for Rh/γ-Al2O3 (up to 120% at 850 °C). In striking contrast, Rh/ACZ (alumina−ceria−zirconia) and Rh/CZ (ceria−zirconia) exhibited marked resistance to sintering, and even moderate (ca. −10% at 850 °C) to pronounced (ca. −60% at 850 °C) redispersion of the Rh. A model is proposed based on a double-layer description of metal−support interactions assigned to back-spillover of labile oxygen ions onto the Rh particles, accompanied by trapping of atomic Rh by the resulting surface oxygen vacancies. This model accounts for the observed resistance to sintering and actual redispersion of Rh, consistent with both alternative sintering mechanisms, namely Ostwald ripening (OR) or particle migration and coalescence (PMC).
