Showing papers on "Platinum published in 1971"

Platinum complexes of unsaturated siloxanes and platinum containing organopolysiloxanes

Abstract: PLATINUM COMPLEXES OF UNSATURATED SILOXANES ARE PROVIDED WHICH ARE USEFUL AS HYDROSILATION CATALYSTS. THESE PLATINUM-SILOXANE COMPLEXES MUST CONTAIN LESS THAN ABOUT 0.1 GRAM ATOM OF HALOGEN, PER GRAM ATOM OF PLATINUM, AND PREFERABLY SUBSTANTIALLY FREE OF HALOGEN WHICH INCLUDE PLATINUM-SILOXANE COMPLEXES WHICH ARE SUBSTANTIALLY FREE OF INORGANIC HALOGEN. THESE PLATINUM-SILOXANE COMPLEXES CAN BE MADE BY EFFECTING CONTACT BETWEEN A PLATINUM HALIDE AND AN UNSATURATED SILOXANE, FOR EXAMPLE, 1,3-DIVINYLTETRAMETHYLDISILOXANE, AND REMOVING AVAILABLE INORGANIC HALOGEN FROM THE RESULTING MATERIAL. IN ADDITION, CURABLE ORGANOPOLYSILOXANE COMPOSITIONS ARE PROVIDED COMPRISING AN ORGANOPOLYSILOXANE POLYMER AND AN EFFECTIVE AMOUNT OF SUCH PLATINUM-SILOXANE COMPLEX.

Promising catalyst for auto exhaust.

Abstract: Lanthanum cobalt oxide as potential auto exhaust catalyst from studies of activity in gas phase

Platinized platinum electrodes

Abstract: The platinized platinum electrode is the most widely used type of electrode. It makes a regular appearance in conductance cells, forms the basis of the hydrogen reference electrode, and is unsurpassed as an electrocatalyst in fuel cells. Yet the mechanism of the formation of the platinum deposit has been investigated only recently, and information on the properties of the electrode (its appearance, structure, area, and reproducibility), and how these are affected by its method of preparation, is widely scattered and not well known. The main factors are critically assessed in this review.

Low‐temperature migration of silicon in thin layers of gold and platinum

Abstract: The backscattering method is employed to obtain microscopic information about solid‐solid reactions of Si with thin layers (500–2000 A) of both vacuum‐evaporated Au and sputtered Pt. A remarkable observation is the migration of Si atoms into Au and Pt at relatively low temperatures (150 and 350 °C, respectively). Migration of Si in Pt induces first the formation of Pt2Si‐like compounds and then PtSi. In the Au–Si system, on the other hand, Si moves through and accumulates on the Au surface in the form of SiO2 under an oxidizing heat‐treatment atmosphere.

Electronic Spectra of Square-Planar Bis(tertiary phosphine)dialkynyl Complexes of Nickel(II), Palladium(II), and Platinum(II)

Abstract: Electronic spectra of trans-[L2M(C≡CR)2], (L=tertiary phosphine or tertiary stibine, and M=Ni, Pd or Pt) have been studied in solution from 220 mμ to 360 mμ. Nickel and platinum complexes showed three intense absorption bands. The lowest energy band was particularly sensitive to substituents of alkynyl groups. This band was assigned empirically to the transition between the molecular orbitals involved in metal-alkynyl bonds. The possibility of π-interaction between the two alkynyl groups through central metal was discussed in relation to the influence of R.

Zerovalent platinum chemistry. Part VI. The reactions of bis- and tris-triphenylphosphineplatinum(0) with hydrogen sulphide, hydrogen selenide, sulphur, and related molecules

Abstract: The reactions of Pt(PPh3)n(n= 2 or 3) with H2M, HMPh, and M (M = S or Se) to form adducts have been studied. The reactivity of the products towards soft and hard reagents has been investigated and compared with that of related H2M, HMPh, and M adducts of some RhI and IrI triphenylphosphine complexes. The results agree with the proposed mechanisms of poisoning of metal surfaces by species such as H2M or M.

A study of grain-boundary grooving at the platinum/alumina interface

Abstract: Grain-boundary grooving at the interface between solid platinum and solid alumina has been studied and its relevance to spheroidisation and particle coarsening noted. Analysis of the equilibrium shape of the grooves in conjunction with zero creep studies on platinum shows that the platinum/alumina interfacial energy is 1050 ergs/cm2 at 1400° C. The rate of growth of the grooves shows that volume diffusion is the operative mass transport mechanism at all temperatures considered (1240 to 1540° C); however, there are indications that diffusion through the metal is rate-determining at lower temperatures (< 1410° C) while diffusion through the ceramic phase predominates at higher temperatures.

An improvement in the carbon-reduction method for the oxygen isotopic analysis of sulphates

Abstract: The carbon-reduction technique for the oxygen isotopic analysis of sulphates has been further developed to improve its reliability for isotopic ratio measurements. Barium sulphate is reduced with carbon at 1, 000°C in a thin platinum boat as an electric resistance heating element to evolve carbon dioxide and carbon monoxide. The carbon monoxide is converted by a high-voltage (3.0kV) discharge between two parallel platinum plates in a liquid-nitrogen cooled vessel. The barium sulphate precipitated from the solution containing sulphate ions by the standard procedure can be reduced with a 98 ± 2% yield of oxygen as carbon dioxide, and analysed with the reproducibility of 0.1-0.25‰ for the oxygen isotopic ratio. No significant memory effect is observed in the analyses of barium sulphates having oxygen isotopic ratios in the range from -1 to +46‰ (SMOW).

Platinum-tin uniformly dispersed hydro-carbon conversion catalyst and process

Abstract: A CATALYSTIC COMPOSITE COMPRISING A COMBINATION OF CATALYTICALLY EFFECTIVE AMOUNTS OF A PLATINUM GROUP COMPONENT, A TIN COMPONENT AND A HALOGEN COMPONENT WITH A POROUS CARRIER MATERIAL IS DISCLOSED. THE PLATINUM GROUP, TIN AND HALOGEN COMPONENTS ARE PRESENT IN THE COMPOSITE IN AMOUNTS, CALCULATED ONAN ELEMENTAL BASIS, OF ABOUT 0.01 TO ABOUT 2 WT. PERCENT PLANTINUM GROUP METAL, ABOUT 0.01 TO ABOUT 5 WT. PERCENT TIN, AND ABOUT 0.1 TO ABOUT 3.5 WT. PERCENT HALOGEN. MOREOVER, THE TIN COMPONENT IS UNIFORMLY DISPERSED THROUGHOUT THE POROUS CARRIER MATERIAL IN A PARTICULE SIZE HAVING A MAXIMUM DEMENSION LESS THAN 100* A., AND SUBSTANTIALLY ALL OF THE PLATINUM GROUP COMPONENT IS PRESENT AS THE ELEMENTAL METAL AND SUBSTANTIALLY ALL OF THE TIN IS PRESENT IN AN OXIDATION STATE ABOVE THAT OF THE ELEMENTAL METAL. THE PRINCIPAL UTILITY OF THE SUBJECT COMPOSITE IS IN THE CONVERSION OF HYDROCARBONS, PARTICULARLY IN THE REFORMING OF A GASOLINE FRACTION. A SPECIFIC EXAMPLE OF THE CATALYST DISCLOSED IS A COMBINATION OF A PLATINUM GROUP METAL, TIN OXIDE AND HALOGEN WITH AN ALUMINA CARRIER MATERIAL WHEREIN THE TIN OXIDE COMPONENT IS UNIFORMLY DISPERSED THROUGHOUT THE ALUMINA CARRIER MATERIAL IN A RELATIVELY SMALL PARTICLE SIZE AND WHEREIN THE COMPOSITE CONTAINS ON AN ELEMENTAL BASIS 0.01 TO 2 WT. PERCENT PLATINUM METAL, 0.01 TO 5 WT. PERCENT TIN AND ABOUT 0.1 TO 3.5 WT. PERCENT HALOGEN.