Download or read book OBTENTION D HYDROCARBURES LEGERS VIA CO H 2 CO 2 H 2 SUR MATERIAUX COMPOSITES FE CO METAL written by FABRICE.. TIHAY and published by . This book was released on 2000 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: LES PRINCIPAUX CATALYSEURS UTILISES POUR L'HYDROGENATION DU MONOXYDE DE CARBONE (OU SYNTHESE FISCHER-TROPSCH) POUR LA PRODUCTION D'HYDROCARBURES SONT A BASE DE FER ET/OU DE COBALT. AUSSI BIEN POUR LES CATALYSEURS A BASE D'OXYDE DE FER QUE POUR CEUX A BASE DE COBALT, UN TRAITEMENT REDUCTEUR SOUS HYDROGENE ET/OU MONOXYDE DE CARBONE EST NECESSAIRE A LEUR MISE EN REGIME. AINSI LA PREPARATION DE CATALYSEURS A BASE DE FER ET DE COBALT, CONTENANT UNE PHASE METALLIQUE ET UNE PHASE OXYDE SANS TRAITEMENT REDUCTEUR PREALABLE, POUR LA PRODUCTION D'HYDROCARBURES INSATURES SEMBLE INTERESSANTE. LA SYNTHESE DE TELS MATERIAUX A ETE REALISEE PAR VOIE DOUCE ET REPOSE SUR LA DISMUTATION DU FE(II) EN FE(0) ET EN MAGNETITE EN MILIEU AQUEUX FORTEMENT BASIQUE ET CHAUFFE. EN PRESENCE DE COBALT(II), LA REACTION D'OXYDO-REDUCTION FE 0 + CO 2 + FE 2 + + CO 0 A LIEU. AINSI, UN MATERIAU NANO-COMPOSITE, STABLE A L'AIR, CONTENANT UN ALLIAGE (CO-FE) ET UNE MAGNETITE DE COBALT EST OBTENU. LA FORMULE DE CE COMPOSITE PEUT S'ECRIRE (CO-FE) CO XFE 1 XO 4. LE MATERIAU EST COMPOSE PRINCIPALEMENT DE MAGNETITE AU COBALT ET D'UN ALLIAGE (CO-FE) DE STRUCTURE C.C. ISOMORPHE DE -FE. LA TRANSFORMATION DE LA STRUCTURE C.C. EN STRUCTURE C.F.C. DE L'ALLIAGE (CO-FE), OBSERVEE POUR UNE TEMPERATURE SUPERIEURE A 430\C, REVELE UN ENRICHISSEMENT DE L'ALLIAGE EN COBALT. CET ENRICHISSEMENT EN COBALT S'EXPLIQUE PAR LA REACTION D'OXYDO-REDUCTION ENTRE LE FE(0) DE L'ALLIAGE ET LE CO(II) DE LA PHASE SPINELLE. L'ETUDE A CONSISTE A RELIER LES DIFFERENTES CARACTERISTIQUES DU CATALYSEUR (RAPPORT CO/FE, ETAT DE SURFACE OBSERVE PAR XPS, MET, MEB) AUX PROPRIETES CATALYTIQUES. AINSI, ON OBSERVE QU'UN CATALYSEUR AYANT SUBI UN TRAITEMENT FLASH SOUS ARGON A 800\C, CONDUIT A UNE SELECTIVITE VERS DES HYDROCARBURES LOURDS (>70% EN MASSE). CECI A ETE RELIE A LA PRESENCE DE CO 3O 4 EN SURFACE DU CATALYSEUR. EN REVANCHE, POUR LES CATALYSEURS N'AYANT PAS SUBI DE TRAITEMENT THERMIQUE, LA SELECTIVITE EST ORIENTEE VERS LES HYDROCARBURES LEGERS (C 2-C 4).

Download or read book Composites m tal carbone obtenus par dismutation catalytique de CO written by Marc Audier and published by . This book was released on 1980 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: THERMODYNAMIQUE ET CINETIQUE DE DISMUTATION DE CO AVEC FE, NI, CO ET LEURS ALLIAGES. IDENTIFICATION DES COMPOSITES METAL-CARBONE. MECANISME DE DISMUTATION: LOI CINETIQUE. ACTIVITE POUR LA SYNTHESE D'HYDROCARBURES

Download or read book The Natural Radiation Environment VII written by S. E. Simopoulos and published by Elsevier Science Limited. This book was released on 2005 with total page 1191 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Natural Radiation Environment Symposium (NRE VII), the Seventh in the NRE series, which commenced forty years ago in 1963 at Rice University Texas, was held in Rhodes (Greece) in May 2002. During the intervening four decades the research work presented at these NRE Symposia has contributed to a deeper understanding of natural radiation and in particular of its contribution to human radiation exposures. It is clear from the quality and diversity of the 143 papers in this volume of Radioactivity in the Environment series that the study of the natural radiation environment is an active and continually expanding field of research. The papers in this volume fall into a number of main and topical research areas namely: the measurement and behaviour of natural radionuclides in the environment cosmic radiation measurement and dosimetry the external penetrating radiation field at ground level TENR (Technologically Enhanced Natural Radiation) and NORM (Naturally Occurring Radioactive Materials) studies assessment of the health effects of radon regulatory aspects of natural radiation exposures In these papers the results of many new surveys of natural radionuclide levels in the environment and of improved methods of detection are described. While some of the natural radiation sources investigated are unmodified by human activity, many accounts are given here of exposures to natural sources which have been enhanced by technology. Such TENR and NORM exposures are shown to range from activities such as mining, oil and gas exploitation, the use of industrial by-products as building materials, to space travel to name but a few. In several cases quite high doses to some individuals are shown to occur. Accounts are given here of methods to prevent and reduce exposures to such sources.

Download or read book Protection of the Ozone Layer written by and published by . This book was released on 1995 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Tropical Timber Agreement 1994 written by United Nations Conference on Trade and Development and published by New York and Geneva : United Nations. This book was released on 1994 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: