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Session Chairperson: Prof. Dr. D.V. Drobot, Moscow State Academy of Fine Chemical Technologies, Pr. Vernadskogo 86, 117571 Moscow, Russia
PREPARATION OF NANOSIZED RHENIUM OXIDE AND RHENIUM BASED METAL PARTICLES BY THERMAL DECOMPOSITION OF ORGANIC PRECURSORS: G.A. Seisenbaeva, D.V. Drobot, Moscow State Academy of Fine Chemical Technologies, Pr. Vernadskogo 86, 117571 Moscow, Russia; V.G. Kessler, Moscow State University; Moscow, Russia; M. Sundberg and M. Nygren, Arrhenius Laboratory, University of Stockholm, Sweden
The thermal decomposition of the organic derivatives of rhenium (Re4O2(OMe)16 (I), ReMoO2(OMe)7 (II), Re4-xWxO2 (OMe)16 (III), Re2O5(acac)2 (IV)) in air at temperatures below 400°C leads in case of I, III and IV to the oxide powders containing fine particles (40-60 Å) with ReO3 type structure included into amorphous matrix, while in case of II a mixture of ReO3 and MoO3 phases was obtained. In an inert atmosphere (N2, Ar) at 300-400°C. I also gives a ReO3 phase, II and III give a pseudocubic phase with Re1-xMxO2 composition (M=Mo, x ¾ 0.25), while IV provides spherical amorphous particles (~1 µm size) of rhenium metal. The reduction of I-III in hydrogen atmosphere leads to formation of single-phase metal product (with the -phase alloy structure) at the temperature about 300-400°C.
SOFT CHEMISTRY ROUTE TO RHENIUM-BASED MATERIALS: V.G. Kessler, Moscow State University; Moscow, Russia; G.A. Seisenbaeva, D.V. Drobot, Moscow State Academy of Fine Chemical Technologies, Pr. Vernadskogo 86, 117571 Moscow, Russia
The so called soft chemistry approach is usually based on hydrolytic or pyrolytic decomposition of the complexes of metals with organic ligands. The methoxides of rhenium (I), rhenium and molybdenum (II) and rhenium and tungsten (III) were prepared by anodic oxidation of rhenium metal in methanol in the presence of LiCl as electrolyte and methoxides of countermetals. Acetylacetonate, Re2O5(acac)2 (IV) was obtained by interaction of re2O7 and Hacac in toluene. I and III are insoluble in common organic solvents and air stable in contrast to highly soluble and air and moisture sensitive II. IV is insoluble in hydrocarbons and dissolves in ethers with decomposition. All these compounds are volatile at reduced pressure and decompose in inert atmosphere into mixed low-valent oxides or, in case of IV, into rhenium metal.
REDUCTION OF AMMONIUM PERRHENAT TO METAL RHENIUM: V.P. Seleznev, D. Mendeleev, University of Chemical Technology of Russia, Miusskaya Sq. 9, Moscow 125047, Russia
BINUCLEAR RHENIUM CLUSTERS AS A BASIS FOR METAL COATINGS AND NEW FUNCTIONAL MATERIALS: A.V. Shtemenko, Ukrainian State University of Chemical Technology, Gagarin Av. 8, Dniepropetrovsk 320005, Ukrainia
Thermal behaviour of binuclear halogenated and halogencarboxylated Re26+ clusters, synthesized according to elaborated procedures, is studied. It is shown, that the last stage of thermal distribution of the substances in vacuum or inert atmosphere is formation of metal rhenium with content of contaminants 0,001-0,01%. Method of obtaining of composite material of "metal-oxide" type is elaborated, providing the best combination of thermophysical and mechanical properties in wide temperature intervals. Density of rhenium framework of the material approaches to that of theoretical and microhardness of 250-260 kg/mm2.
THE CATALYTIC PROPERTIES OF SUPPORTED RHENIUM AND RHENIUM HEPTASULFIDE: Margarita A. Ryashentseva, Zelinski Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow, Leninsky prospect 47, Russian
The catalytic properties of supported rhenium were widely investigated in the reactions of de, hydrogenation, hydrogenation of hydrocarbons and reforming of petrol fractions. Lowpercentage bimetallic supported catalysts containing rhenium and palladium have been developed. A world first publication of these results were in 1960's - a little bit earlier than known Pt - Re reforming catalysts. An effective catalyst, rhenium heptasulfide has been found in the chemical synthesis of S - and N - containing heterocycles compounds. It is a specific selective catalyst for the hydrogenation of the pyridine ring without affecting the benzene ring in aryl-substituted pyridines, including those containing silicon, isoquinolines, annelated pyridine and condensed aromatic compounds. The process of hydrogenation in the presence of alcohols is going on along with N - alkylation on rhenium heptasulfide. Selective hydrogenation of various number of physiologically active substances, containing a pyridine ring could afford some alkaloids and their analogs.
9:50 am BREAK
CHEMISTRY OF BINUCLEAR RHENIUM CLUSTERS: A.V. Shtemenko, B.A. Bovykin, Ukrainian State University of Chemical Technology, Gagarin Av. 8, Dniepropetrovsk 320005, Ukrainia
Binuclear rhenium clusters are the first examples of inorganic substances, which contain multiple metal-metal bond, that is the reason of some special (unique) properties of these compounds. Mechanism of formation of Re3+ clusters is thoroughly studied by us that became the base of elaboration of new technological methods of synthesis of different types of binuclear Re26+ clusters. On the base of accomplished investigations the perspective of binuclear rhenium clusters application is shown as precursors for obtaining of rhenium and new inorganic materials on it's basis, catalysis and promotors of catalytic systems among them.
SOLID STATE CHEMISTRY OF RHENIUM HALOGENIDE AND OXIDES: D.V. Drobot, Moscow State Academy of Fine Chemical Technologies, Pr. Vernadskogo 86, 117571 Moscow, Russia; M.B. Varfolomeev, Institute of the Chemical Problems of Microelectric, Pr. Vernadskogo 86, 117571 Moscow, Russia
Results of the investigations of the phase equilibriums in the systems Re-O-Hal (Hal = C1, Br, I) individual phases M(ReO4)3 (M = metals of the III group) in systems Re-O-M and corresponded crystallohydrates M(ReO4)3nH20 (n = 3; 4; 4,5 and 8) are discussed. By experimental dates P-T-x diagrams of binary systems are obtained and it is shown that oxohalides Re204Cl5 (Hal = Cl, Br) can be obtained. By means of vapour pressure measurements thermodynamic dates for sublimation and vaporisation processes of individual phases are obtained. Thermostability of ReI3-x and lower rhenium iodides is investigated. The processes of chlorination of Re(IV) and Re(VI) oxides are investigated. Total results are the importance for CVD processes and technology of Re compounds purification. The methods of controlled synthesis ReO3, ReHalx, ReOyHalx, M(ReO4)3 and M(ReO4)3 nH20 are described. Crystall structure and thermal stability of M(ReO4)3 and M(ReO4)3 nH20 are investigated. It is shown that crystal! structure of M(ReO4)3 nH20 depends on the size of ri for M3+.
USAGE OF ELECTRODIALYSIS METHOD FOR PREPARING HIGH-PURITY RHENIUM CHEMICAL COMPOUNDS: A.V. Elutin, M.V. Istrashkina, Z.A. Peredereeva, State Research Centre-State Institute of Rare Metals-GIREDMET, 5 B. Tolmachevsky Per., Moscow 109017, Russia
This report presents the results of studies the process of electrodialysis of rhenium-containing solutions. It contains experimental data obtained by studying transport of rhenium and impurity elements through different membranes and selection of optimal electromembrane system, electrode materials and ion-exchange membranes. The received data have allowed to develop methods of electrodialysis conversion of potassium perrhenate to superpure ammonium perrhenate and preparation of highpurity concentrated perrhenic acid by treatment of contaminated salts. It is found that the method of electrodialysis is very efficient for recovery of rhenium from complicated sulphuric-acid solutions containing molybdenum, iron, zinc, lead and other elements. The described methods are successfully used at Russian enterprises.
PROGRESS IN ANALYTICAL CHEMISTRY OF RHENIUM: Ludmilla V. Borisova, V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 117975 Moscow, Kosygin Str. 19, Russia
Rhenium speciations in various solutions, which are important for process and analytical chemistry have been studied for many years. Model systems, containing Rhenium, different ligands and reductors, equilibrium diagrams of Rhenium compounds were studied. Analytical forms of Rhenium compounds and their properties (oxidative-reductive, complexability, catalytical and etc.), their composition, structure, mechanism and reaction kinetics with the used of WMS, IR, ESR, NMR and kinetic spectroscopy methods were revelated. Effective analytical systems were discovered on the basis of these investigations. Perspective methods of optical and potentiometrical sensors, catalytic methods for cone. of alkaline and acid medias with detection limit down to 0.001 µgRe/ml, coulometric method for mg Re determination, ICPAES, luminescence, thermochromatographical, spectrophotometric, ESR and other methods were developed. Some of them are in use as FIA detectors. New sorbents, watersoluable polymers with membrane filtration, electrodialysis and electromigration appeared to be the base for effective isolation and preconcentration of Rhenium. Express-testing methods, based on the catalytic properties of "unusual" state of oxidation Rhenium - Re (VI), were created and applied for analytical control on several manufactures (limit of detection up to 0.001 µg/ml). The developed methods comprise the basis of analytical control during the reworking of Rhenium-containing ores, technological rests, waste Re-Pt catalysators, volcanic products from Kurila Islands, being used in field conditions, and also for geochronology by Re/Os isotop ratio.
RHENIUM (I)-CARBONYL COMPOUNDS OF DI-2-PYRIDYL KETONE: ELECTROCHEMICAL SENSORS FOR ELECTROPHILES AND METAL IONS: Mohammed Bakir, Department of Chemistry, The University of the West Indies, Mona Campus, Kingston 7, Jamaica, W.I.
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