Influence of the redox properties of ceria on the preparation of three-way automotive platinum—rhodium/ alumina—ceria catalysts

• Published in: Applied catalysis. B, Environmental Vol. 5; no. 1-2; pp. 57 - 69
• Main Authors: Marécot, P., Pirault, L., Mabilon, G., Prigent, M., Barbier, J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.12.1994; Elsevier
• Subjects: Catalysis; Catalysts: preparations and properties; Ceria; Chemical Sciences; Chemistry; Exact sciences and technology; Exhaust; General and physical chemistry; Inorganic chemistry; Material chemistry; Platinum—rhodium; Propane oxidation; Propene oxidation; Redox properties; Temperature-programmed reduction; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Exhaust; Temperature-programmed reduction; Propene oxidation; Ceria; Propane oxidation; Redox properties; Platinum—rhodium; Mixed catalyst; Cerium Oxides; Catalytic reaction; Hydrocarbon; Transition metal; Experimental study; Supported catalyst; Thermal stability; Heterogeneous catalysis; Gamma form; Propene; Rhodium; Platinum; Preparation; Three way catalyst; Oxidation; Platinoid; Alumina; Propane
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/0926-3373(94)00038-7

The redox properties of ceria were investigated by temperature-programmed reduction performed under hydrogen and the catalysts were evaluated by determining the temperatures at which 50% conversion for propene and propane oxidation were reached. The results obtained show that ceria plays a decisive role within the preparation of bimetallic PtRh/Al2O3CeO2 catalysts by successive impregnations (SI) when reduced capping cerium atoms (Ce3+) are present on the parent Pt/Al2O3CeO2 catalyst before introduction of the rhodium salt. Thus, rhodium deposition would occur by a redox reaction between Ce3+ and Rh3+. The preparation procedure of PtRh/Al2O3CeO2 catalysts by the SI method increases the thermal stability of the metallic species under oxidizing conditions. This improvement would be the consequence of a higher resistance to the formation of PtRh alloys with surface enrichment in rhodium.