The effect of CeO2 on the surface and catalytic properties of Pt/CeO2-ZrO2 catalysts for methane dry reforming
The CO2 reforming of CH4 over Pt catalysts supported on nanocrystalline mesoporous ZrO2 and CeO2-ZrO2 carriers was investigated at atmospheric pressure. The effect of CeO2 content (1-12 wt%) on the surface and catalytic properties of the catalysts was studied. It was found that the pre-treatment temperature and the concentration of CeO2 influence on the morphology of Pt particles. The calcination temperature as high as 1073 K leads to sintering of Pt particles deposited over zirconia- and CeO2-loaded zirconia substrates. Temperature-programmed reduction (TPR) results showed good reductive properties for Pt/CeO2-ZrO2 catalysts due to both, the high surface shell reduction of zirconia and the synergetic effect between Pt and CeO2. X-ray photoelectron spectroscopy (XPS) of reduced catalysts revealed the presence of different Pt oxidation state depending on the catalyst composition. Stabilization of partially oxidized platinum species by ceria was detected for the reduced Pt/CeO2-ZrO2 samples. An activation period was required for the stabilization of the activity of Pt/CeO2-ZrO2 catalysts. The high stability of Pt/CeO2-ZrO2 catalysts was related to the close contact between Pt and CeO2. (C) 2009 Elsevier B.V. All rights reserved.
Applied Catalysis B-Environmental
CSIC (Spain); CAM [CCG07-CSIC/ENE-1884]; NFS-Bulgaria [X-1515/05]; Ministry of Education and Culture (Spain) [SAB2005/0035]