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- Volume 47, Issue 3, 2003
Platinum Metals Review - Volume 47, Issue 3, 2003
Volume 47, Issue 3, 2003
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Nucleation and Growth of Platinum Clusters in Solution and on Biopolymers
The molecular mechanisms of platinum cluster nucleation and growth in solution and on biopolymers have been investigated by means of first-principles molecular dynamics. In contrast with the classical picture where clusters nucleate by aggregation of metallic Pt(0) atoms, it was found that Pt-Pt bonds can form between dissolved Pt(II) complexes after only a single reduction step. Furthermore, small clusters were observed to grow by addition of unreduced [PtCl2(H2O)2] complexes, in agreement with an autocatalytic growth mechanism. Moreover, Pt(II) ions covalently bound to biopolymers were found to act as preferential nucleation sites for the formation of clusters. This is a consequence of the presence of heterocyclic donor ligands which both enhance the electron affinity of the metal nuclei and induce the formation of metal-metal bonds that are stronger than those obtained in solution. In fact, in metallisation experiments a clean and purely heterogeneous metallisation of single DNA molecules leading to thin and uniform Pt cluster chains extending over several microns was obtained.
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Strengthening Platinum-Palladium-Rhodium Alloys by Ruthenium and Cerium Additions
Authors: By Yuantao Ning and Hu XinThe effects of cerium and ruthenium additions on the mechanical properties of Pt-15 Pd-3.5 Rh alloy (wt.%) at ambient and high temperature are examined. The mechanical properties of the alloy were improved by adding cerium (≤ wt.%) or ruthenium (≤ 0.5 wt.%) solute, with the cerium additions giving a better strengthening effect. Higher concentrations of cerium and ruthenium did not visibly increase the strength properties of the Pt-15Pd-3.5Rh alloy and even reduced some of the mechanical properties at high temperature. Increasing the palladium content in the Pt-Pd-Rh alloy could enhance the alloy strengths at room temperature but damaged the mechanical properties at high temperatures. Observations of the morphologies of fracture sections of alloy samples after creep-rupture tests at high temperature showed ductile fracture for alloys with lower contents of palladium, cerium or ruthenium and brittle fracture for alloys with higher contents ofpalladium, cerium or ruthenium. The different strengthening mechanisms of palladium, cerium and ruthenium additions to Pt-15Pd-3.5Rh alloy are discussed.
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Johnson Matthey Catalysts Division
In November 2002, Johnson Matthey completed the acquisition from ICI of its Synetix business. Synetix was added to Johnson Matthey’s Catalysts & Chemicals Division, which was then renamed Johnson Matthey Catalysts. This division comprises Process Catalysts and Technologies (PCT), Environmental Catalysts and Technologies (ECT) and Fuel Cells. The former Synetix businesses, now part of PCT, bring a complementary range of base metal technologies to Johnson Matthey’s traditional precious metals catalysis business.
Synetix was formed in 1998 from three ICI businesses: Katalco, Vertec (adhesion promoters) and Tracerco, and from businesses from Unilever: Unichema catalysts and the HTC catalysts business from Crosfield. It also included the former BASF syngas catalysts, linked to the ammonia and methanol markets.
Subsequently, units such as J & J Dyson’s ‘Dycat’ business related to the hydrogen industry and to refineries and the oil and gas areas, and the former catalyst units of Celanese: ‘Hoecat’ for edible oils and ‘CelActiv‘ linked to the alcohol sector, were acquired. In India, the catalyst business of Hindustan Lever - linked with oleochemicals and the Taloja facility for catalysts for oleochemicals and edible oils, were also acquired.
Synetix also brings expertise in chiral catalysis.
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Recovery of Value Fission Platinoids from Spent Nuclear Fuel
Authors: By Zdenek Kolarik and Edouard V. RenardSeveral processes are reviewed for recovering fission platinoids from radioactive liquids and solid material that typically originate during the reprocessing of spent nuclear fuel by the Purex process. The liquids are radioactive high-level liquid waste and the solution obtained on dissolving the spent nuclear fuel in nitric acid (dissolver solution). The solid is the undissolved fuel residue (dissolver residue). The processes described here have been particularly developed to recover platinoids or, if aimed at the separation of actinides, platinoid recovery is included. Hydrometallurgical processes are predominantly based on solvent extraction, electrodeposition and ion exchange, and less frequently on precipitation and extraction chromatography. Pyrochemical processes are based on extraction or distillation.
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Volumes & issues
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Volume 58 (2014)
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Volume 57 (2013)
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Volume 56 (2012)
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Volume 55 (2011)
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Volume 54 (2010)
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Volume 53 (2009)
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Volume 52 (2008)
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Volume 51 (2007)
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Volume 50 (2006)
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Volume 49 (2005)
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Volume 48 (2004)
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Volume 47 (2003)
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Volume 46 (2002)
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Volume 45 (2001)
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Volume 44 (2000)
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Volume 43 (1999)
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Volume 42 (1998)
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Volume 41 (1997)
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Volume 40 (1996)
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Volume 39 (1995)
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Volume 38 (1994)
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Volume 37 (1993)
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Volume 36 (1992)
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Volume 35 (1991)
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Volume 34 (1990)
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Volume 33 (1989)
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Volume 32 (1988)
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Volume 31 (1987)
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Volume 30 (1986)
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Volume 29 (1985)
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Volume 28 (1984)
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Volume 27 (1983)
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Volume 26 (1982)
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Volume 25 (1981)
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Volume 24 (1980)
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Volume 23 (1979)
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Volume 22 (1978)
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Volume 21 (1977)
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Volume 20 (1976)
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Volume 19 (1975)
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Volume 18 (1974)
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Volume 17 (1973)
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Volume 16 (1972)
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Volume 15 (1971)
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Volume 14 (1970)
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Volume 13 (1969)
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Volume 12 (1968)
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Volume 11 (1967)
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Volume 10 (1966)
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Volume 9 (1965)
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Volume 8 (1964)
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Volume 7 (1963)
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Volume 6 (1962)
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Volume 5 (1961)
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Volume 4 (1960)
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Volume 3 (1959)
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Volume 2 (1958)
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Volume 1 (1957)