Ceria-Praseodymia Mixed Oxides: Relationships Between Redox Properties and Catalytic Activities Towards NO Oxidation to NO2 and CO-PROX Reactions

• Published in: Topics in catalysis 2016-07, Vol.59 (10-12), p.1065-1070
• Main Authors: Giménez-Mañogil, Javier, Guillén-Hurtado, Noelia, Fernández-García, Susana, Chen, Xiaowei, Calvino-Gámez, José Juan, García-García, Avelina
• Format: Article
• Language: English
• Subjects: Catalysis; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Original Paper; Pharmacy; Physical Chemistry
• ISSN: 1022-5528; 1572-9028
• DOI: 10.1007/s11244-016-0591-1

A series of Ce x Pr 1−x O 2−δ catalysts was prepared by co-precipitation method in alkali media. These catalysts were characterized by N 2 adsorption–desorption isotherms at −196 °C, X-ray diffraction, thermogravimetry combined with mass spectrometry (TG-MS), and temperature-programmed reduction with H 2 and CO (H 2 -TPR and CO-TPR, respectively). Catalytic tests were performed for temperature programmed NO oxidation to NO 2 (from 25 to 750 °C) and for the preferential oxidation of CO in H 2 rich stream (CO-PROX reaction) in the range of 150–500 °C. The trends in the order of catalytic activities towards NO oxidation and CO-PROX are correlated with the redox properties of the catalysts and their composition. Ce x Pr 1−x O 2−δ mixed oxides present very different catalytic behaviours towards NO oxidation and CO-PROX reactions. These experimental trends might be explained by the balance of several factors: the acid character of the NO and CO molecules, the different lattice oxygen mobility of the catalysts, the presence of surface carbonates species in the samples, and the catalysts’ reducibility under H 2 and CO. The understanding of the features that govern the activity towards these environmentally relevant oxidation reactions is important in the designing of effective catalysts.