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Platinum Group Metals (platinum + group_metal)
Selected AbstractsVoltammetric Analysis of Trace Levels of Platinum Group Metals , Principles and ApplicationsELECTROANALYSIS, Issue 21 20072Article first published online: 4 OCT 200, Clinio Locatelli Abstract The compelling use of autocatalytic converters, containing platinum group metals (PGMs), has been the cause, in the environmental and biological matrices, of an increasing concentration of such metals. For this reason, in the last decade, the literature has reported several papers regarding analytical procedures for the determination of Pt(II), Pd(II) and Rh(III) in real samples, generally employing spectroscopic methods. The present review intends to highlight the contribution of the voltammetric techniques for the determination of these metals, including also those less investigated, i.e. Iridium, Osmium and Ruthenium. [source] Selective Oxidation of Alcohols to Carbonyl Compounds and Carboxylic Acids with Platinum Group Metal CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2003Ross Anderson Abstract The use of platinum group metal (PGM) catalysts for the selective oxidation of various primary and secondary alcohols under mild conditions is described. High throughput screening (HTS) techniques have been used to identify trends in catalyst activity and product selectivity. Using air as oxidant and water as solvent 5% Pt, 1% Bi/C has been identified as an efficient catalyst for the transformation of 2-octanol to 2-octanone and 1-octanol to octanoic acid. To improve aldehyde selectivity the promotion of Pt/Al2O3 and Ru/C catalysts has been investigated. The use of H2O2 as oxidant has been demonstrated as a suitable alternative to air. [source] Voltammetric Analysis of Trace Levels of Platinum Group Metals , Principles and ApplicationsELECTROANALYSIS, Issue 21 20072Article first published online: 4 OCT 200, Clinio Locatelli Abstract The compelling use of autocatalytic converters, containing platinum group metals (PGMs), has been the cause, in the environmental and biological matrices, of an increasing concentration of such metals. For this reason, in the last decade, the literature has reported several papers regarding analytical procedures for the determination of Pt(II), Pd(II) and Rh(III) in real samples, generally employing spectroscopic methods. The present review intends to highlight the contribution of the voltammetric techniques for the determination of these metals, including also those less investigated, i.e. Iridium, Osmium and Ruthenium. [source] The use of sodium formate for the recovery of precious metals from acidic base metal effluentsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2001Herman G Julsing Abstract Zinc was used for the reduction of the platinum group metals (PGMs) in acidic effluents. Due to the increasing cost of zinc, sodium formate was investigated as an alternative reductant. In a base metal-containing acidic effluent, called diethylenetriamine barren, sodium formate was used to precipitate the PGMs. This effluent was the filtrate obtained after a precipitation procedure had been used to remove rhodium and iridium. It was found that pH 1.5 was the optimum starting pH for sodium formate reduction. The pH increased to approximately 4.5 after the addition of sodium formate. The optimum concentration of sodium formate was found to be 30,g,dm,3 at a temperature of 100,°C where the process time was 6,h. Platinum and palladium were the most effectively reduced PGMs, both exhibiting an average precipitation efficiency of greater than 99%. Difficulty was experienced with the precipitation of iridium (average precipitation efficiency of 76%). The precipitated PGMs readily dissolved in hydrochloric acid (6,M) and sodium chlorate (2%). A reduction in costs resulted from the discontinuation of the use of zinc for reduction purposes. An additional advantage was that zinc was no longer introduced into the PGM refinery circuits. © 2001 Society of Chemical Industry [source] Oxidant-Free Dehydrogenation of Alcohols Heterogeneously Catalyzed by Cooperation of Silver Clusters and Acid,Base Sites on AluminaCHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2009Ken-ichi Shimizu Dr. Abstract Trifunctional green catalysis: In-depth characterization shows that oxidant-free selective oxidation of alcohols by silver nanoparticles on ,-Al2O3, as a new heterogeneous catalyst, proceeds through cooperation of silver, acid, and base sites (see figure). A ,-alumina-supported silver cluster catalyst,Ag/Al2O3,has been shown to act as an efficient heterogeneous catalyst for oxidant-free alcohol dehydrogenation to carbonyl compounds at 373,K. The catalyst shows higher activity than conventional heterogeneous catalysts based on platinum group metals (PGMs) and can be recycled. A systematic study on the influence of the particle size and oxidation state of silver species, combined with characterization by Ag,K-edge XAFS (X-ray absorption fine structure) has established that silver clusters of sizes below 1,nm are responsible for the higher specific rate. The reaction mechanism has been investigated by kinetic studies (Hammett correlation, kinetic isotope effect) and by in situ FTIR (kinetic isotope effect for hydride elimination reaction from surface alkoxide species), and the following mechanism is proposed: 1),reaction between the alcohol and a basic OH group on the alumina to yield alkoxide on alumina and an adsorbed water molecule, 2),CH activation of the alkoxide species by the silver cluster to form a silver hydride species and a carbonyl compound, and 3),H2 desorption promoted by an acid site in the alumina. The proposed mechanism provides fundamental reasons for the higher activities of silver clusters on acid,base bifunctional support (Al2O3) than on basic (MgO and CeO2) and acidic to neutral (SiO2) ones. This example demonstrates that catalysts analogous to those based on of platinum group metals can be designed with use of a less expensive d10 element,silver,through optimization of metal particle size and the acid,base natures of inorganic supports. [source] | ||||||||||