DTA/TGA characterization of ZrXCe1-XO2 catalysts and study of their reactivity in soot oxidation

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EPR study of the rare paramagnetic centres in Ce-based oxides

Electron Paramagnetic Resonance (EPR) measurements have been performed at 4.2 K on MeCeO oxides, where Me = Cu, V, Mn, Mo, with atomic ratio Me/Ce = 0.1. In addition to the paramagnetic species usually observed in such oxides (Cu2+, V4+, Mn2+, Mo5+) and assigned in a previous work, new EPR spectral features have been observed and attributed to Ce3+ ions, to another valence state (V2+) of the vanadium doping ion, to new Mn2+ sites and to paramagnetic impurities ions such as Fe3+ and Er3+

Identification of different Cu

Different copper-titanium oxides were obtained by impregnation of copper nitrate (atomic ratio Cu/Ti = 0.1) on three TiO2 samples with different initial structures: amorphous (AM), anatase (AN) and rutile (RT). X-band Electron Paramagnetic Resonance (EPR) analysis of Cu-TiO2 samples revealed the formation of different copper species depending on the initial structural state of TiO2. Aggregates of Cu(II) ions and isolated Cu2+ ions located either on the surface or in the solids were observed. Copper ions incorporated in anatase exhibit an octahedral symmetry mainly characterized by a significant elongation of Cu-O bonds following the z-axis. With the transformation of TiO2 from the anatase to the rutile form, copper atoms occupied Ti4+ sites in the rutile structure

EPR characterization of Cr

Similar to commercial anatase samples, a well-resolved EPR spectrum has been observed in anatase-TiO2 prepared by Rhône-Poulenc. Using the X and Q-band microwave frequencies, it has been demonstrated that the spectrum is formed by two signals. One, constituted by a fine structure, has been attributed to Cr3+ ions and the other to Cr5+. It seems that these species are responsible for the spectrum when they are simultaneously present in anatase

Catalytic properties of beta zeolite exchanged with Pd and Fe for toluene total oxidation

Siberia: 'Private' house Lake BaikalColorVolume 137, Page 1