Influence of the partner oxide on the catalytic properties of Au/CexZr1-x highly loaded gold catalysts

SSCI-VIDE+ING+FMO:JROInternational audienc

Contribution to the study of the Ce-Zr-Au system

The equilibrium phase diagram of the Ce-Zr-Au system was studied by differential thermal analysis, X-ray diffraction and electron probe microanalysis along the isopletic section at 50 at. % Au. Our main result concerns the discovery of a new ternary phase and a ternary invariant. The polymorphic transitions of the ZrAu phase, previously reported, was confirmed and we precised the melting and the polymorphic transition temperatures of the CeAu phase. A schematic representation of the isopletic section is given

Carbon steel corrosion in clay-rich environment

International audienceWe investigated the carbon steel corrosion in carbon dioxide clay-rich environment to understand its behavior under geological conditions. The results show the formation of magnetite as the main corrosion product in the first step of the corrosion process, followed by the formation of different corrosion products with complex mixtures of iron-oxide, hydroxycarbonate, hydroxychloride and sulfide phases. These results strongly contrast with similar experiments conducted under H-2 atmosphere where the major corrosion products consisted of iron sulfides. It appears then important to consider all the geochemical parameters including gas composition to better study corrosion of steel buried in geological formations. (C) 2014 Elsevier Ltd. All rights reserved

Vapor hydration of a simulated borosilicate nuclear waste glass in unsaturated conditions at 50 degrees C and 90 degrees C

International audienceVapor hydration of a simulated typical French nuclear intermediate-level waste (ILW) glass in unsaturated conditions has been studied in order to simulate its behaviour under repository conditions before complete saturation of the disposal site. The experiments were conducted for one year at 50 degrees C and 90 degrees C and the relative humidity (RH) was maintained at 92% and 95%. The glass hydration was followed by Fourier Transform Infra-Red spectroscopy (FTIR). The surface of the reacted glass was characterised by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The chemical and mineralogical composition of the alteration products were studied by Energy Dispersive X-ray Spectroscopy (EDX) and mRaman spectroscopy, respectively. The glass hydration increased with temperature and RH and led to the formation of a depolymerized gel layer depleted in alkalis. The glass hydration rate decreased with time and remained almost unchanged for the last three months of exposure. Overall, the ILW glass hydration rate was similar to that obtained with the SON68 high-level waste glass