Alloying Effect in Low Loaded Rh Catalysts Supported on High Surface Area Alumina on Their Activity in CH4 and NO Decomposition

In the alloys of transition metals (TM) and main group ones (MGM) the valence electrons from MGM can fill the d band of the TMs entirely and slightly increase the number of electrons in their s band (Azaroff, 1960; Kittel, 2005). Such Rh atoms enriched in electrons, present in Al-Rh alloys, were found to be very active electron donors (Pietraszek et al., 2007). It was revealed that they transfer the electrons to the antibonding Л orbital of adsorbed nitric oxide molecules causing NO decomposition to dinitrogen and dioxygen (Pietraszek et al., 2007). Due to the great difference in the Al and Rh electro-negativity, the alloys are sometimes considered as nonstoichiometric chemical compounds. Because of the large range of nonstoichiometry those compounds should rather be estimated as intermediate phases (IP) (Azaroff, 1960). The presence of the Al-Rh alloy nanocrystallites isostructural with Al9Rh2 (Bostrom et al., 2005) was earlier revealed in the freshly prepared Rh/δAl2O3 catalysts containing 0.06 and 1.5 wt.% Rh (Pietraszek et al., 2007; Zimowska et al., 2006)..

Oxidation of acid-proof steel foil as a method of deposition of phases active in nitrogen oxides decomposition on metallic monolith walls

Pieces of 1H18N9T acid-proof steel foil were subjected to thermoprogrammed oxidation up to 823K, 873K, 1023K and 1113K in air flow. The phases in the oxide layers were determined by Raman spectroscopy. The chemical compositions of the surface microlayers of oxidized foils were investigated by energy dispersive X-ray spectrometry and the chemical compositions of their surface nanolayers were determined by X-ray photoelectron spectrometry. The affinity to oxygen of the foil components was found to be a main factor determining chemical composition and phase structure of the oxides

modélisation des propriétés thermodynamiques de solutions d'électrolytes d'intérêts industriels

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF