title: Influence of the Ce-Zr promoter on Pd behaviour under dynamic CO/NO cycling conditions: a structural and chemical approach.
abstract: The behaviour of the Pd phase in three way catalysts (TWCs) having a Ce-Zr oxide as a promoter component has been examined under CO/NO cycling conditions. In order to extract information on the role of the noble metal and the metal-promoter interface, two catalysts in, respectively, the presence or the absence of the promoter and having a similar Pd particle size were analyzed by a synchronous multitechnique approach using X-ray absorption (XAS) or high energy X-ray diffraction (HXRD) in combination with diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) and mass spectrometry (MS). From a structural point of view it is shown that the promoter oxide strongly influences Pd behaviour, limiting morphological (size/shape) and structural (formation of carbide/oxide phases) modifications occurring under dynamic conditions in the absence of the promoter. Activity measurements show that these phenomena have important chemical consequences in terms of CO/NO pollutant metal coverage(s), the occurrence of NO and/or CO dissociation steps as well as the subsequent transformation of the pollutants into CO2 and N2.
authors.affiliation: Instituto de Catálisis y Petroleoquímica, CSIC, C/Marie Curie 2, 28049-Madrid, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Kubacka
authors.forename: Ana
authors.initials: A
authors.lastname: Iglesias-Juez
authors.forename: M
authors.initials: M
authors.lastname: Di Michiel
authors.forename: Mark A
authors.initials: MA
authors.lastname: Newton
authors.forename: Marcos
authors.initials: M
authors.lastname: Fernández-García
mesh_terms: D002248:Carbon Monoxide / Q000737:chemistry*; D002586:Cesium / Q000737:chemistry*; D015394:Molecular Structure; D009569:Nitric Oxide / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D013816:Thermodynamics; D015040:Zirconium / Q000737:chemistry*
chemical_list: D002586:Cesium; D009569:Nitric Oxide; D010165:Palladium; D002248:Carbon Monoxide; D015040:Zirconium