Showing papers on "Noble metal published in 1984"

A structural investigation of stabilized oxygen evolution catalysts

Abstract: A ternary mixed oxide containing SnO2, RuO2 and IrO2 was shown to exhibit a more stable electrocatalytic behaviour than simpler catalysts consisting of noble metal oxides only. X-ray diffraction and transmission electron microscopy were used to characterize the structure of these oxide catalysts. It was found that precipitation of the fine catalyst powders resulted in the formation of a mixed (Sn, Ru, Ir)O2 rutile phase. This phase was shown to be thermodynamically unstable, decomposing to SnO2 and (Ru, Ir)O2 on annealing at 800° C. X-ray photoelectron spectroscopy revealed that the surface composition of these mixed oxide catalysts varies considerably from the bulk composition. The formation of such metastable, mixed oxides is discussed.

Manufacture of semiconductor device

Abstract: PURPOSE:To obtain a semiconductor device characterized by a low cost and improved reliability, by providing a noble metal layer on the surface of a semiconductor substrate through an ohmic contact layer, performing electrolysis of the surface of the noble metal layer in plating liquid including the ions of the same noble metal, reversing the polarity of a voltage, performing electric plating, thereby forming a uniform rear surface of electrode by few processes. CONSTITUTION:A noble metal layer 8 is provided on the surface of a semiconductor substrate 1 through an ohmic contact layer 7. The surface of the noble metal layer undergoes electrolysis by using plating liquid including the ions of the same noble metal as the noble metal 8. Thereafter, the polarity of a voltage is reversed, and electric plating 9 is performed. For example, the Ti-AuSb layer 7 is formed on the rear surface of a wafer. Then, the surface on the side, where an Ag bump 6 is formed, is covered. The wafer is connected to a positive electrode. A platinum plate is connected to a negative electrode. Ag is plated on the rear surface of the semiconductor substrate 1 in the aqueous solution of AgCN. Then, heat treatment is performed in an N2 atmosphere, and the Ag layer 8 is provided through the ohmic contact layer. Then, the wafer is connected to the positive electrode, and the platinum plate is connected to the negaive electrode, and the electrolysis is performed in the aqueous solution of AgCN. Thus the surface of the Ag layer 8 is cleaned. Then the polarity is immediately reversed, and the plating is performed. Thus the Ag layer 9 is obtained.

Heterogeneous catalysis in organic chemistry. 2. A mechanistic comparison of noble-metal catalysts in olefin hydrogenation

Abstract: Hydrogenation/deuteriation d'olefines cycliques sur des catalyseurs a base de palladium, platine et rhodium sur support de carbone

Conductive pigment-coated surfaces

Abstract: Conductive thick film pigment-coated surfaces which possess desirable conductivity and solderability characteristics are formed from an alloy comprising a mixture of a nonnoble conductive metal, a noble metal and at least one oxidizable material. The oxidizable material is present in the alloy in an amount in the range of from about 5% to about 25% by weight, the nonnoble metal in an amount in the range of from about 94% to about 60% by weight and the noble metal in an amount in the range of from about 1% to about 15% by weight of the alloy. The desired product is prepared by admixing a nonnoble metal, an oxidizable material and a noble metal, arc-melting the mixture to form an alloy, grinding the arc-melted alloy to a powdered form, admixing the powder with the carrier binder, depositing said admixture on an inert surface, firing the admixture and surface in an oxygen-containing atmosphere at a temperature in the range of from about 500° to about 950° C. and fluxing the resultant conductive thick film pigment-coated surface with a zinc-chloride based flux to provide the desired product.

Method of preparing an improved catalyst

Abstract: A reforming catalyst comprising a type L zeolite containing at least one Group VIII noble metal may be prepared by a method involving contacting the freshly prepared catalyst with oxygen, hydrogen or an inert gas and optionally water at elevated temperatures, contacting the catalyst at elevated temperatures with a source of chlorine such as HCl or Cl 2 and preferably oxygen and water, and contacting the catalyst at elevated temperatures with oxygen and optionally water Prior to use the catalyst is reduced by contact at elevated temperatures with hydrogen and optionally water This process enhances the dispersion of the noble metal particles

Neutron Activation Analysis for Platinum Group Elements and Gold in Chromitites

Abstract: Noble metals are inhomobeneously distributed as discrete minerals and to a limited extent in solid solution in sulfides, silicates and chromian spinel. A N1-N1 sulfide bead fire assay technique has been adapted to analyse noble metals in chromiterich rocks and chromitites. The fire assay technique concentrates the noble metals into a nickel sulfide button. Upon dissolution of the button, the Pt group elements and Au remain as a residue and are filtered off for analysis. The previous method employed a sodium borate-sodium carbonate flux which did not dissolve chromite grains. It is found that a lithium tetraborate-sodium carbonate flux attacks the chromite to form a worm-like residium of chromian sesquioxide, which allows access to inclusions and elements held in solid solution in the chromite. Losses during the fire assay have been checked by spiking the charge with noble metal radiotracers and found to be within 10 percent of the amount present. The technique has also been checked by making repl...

Method for making ternary fuel cell catalysts containing platinum cobalt and chromium

Abstract: An improved ternary noble metal-containing, alloy catalyst which has a catalytic activity for the electrochemical reduction of oxygen greater than two and one-half times that of the supported unalloyed noble metal alone. In addition, a disclosure of the method of preparing said catalyst is by intimately contacting two metallic elements with a supported noble metal, then heating this material to form the ternary alloy catalyst. This catalyst has particular utility for the electrochemical reduction of oxygen which makes it particularly useful as a cathode in acid fuel cells. The preferred embodiment of this catalyst is finely divided platinum alloyed with chromium and cobalt supported on an electrically conductive carbon-black support material.

Process for the isolation of noble metals

Abstract: The present invention involves the isolation or leaching of noble metals from materials containing noble metals, e.g. ores, by treating the noble metal- containing materials with a cyclic thiourea derivative under acid pH conditions. Removal is effected by adsorption onto charcoal or by an ion exchanger, for example. Preferred cyclic thioureas are N,N'-ethylenethiourea and N,N'-propylenethiourea and the acid pH conditions may be achieved by sulfuric acid or hydrochloric acid solutions containing 0.01 to 2.0% by weight of the cyclic thiourea.

Preparation of carboxylic acid anhydrides

Abstract: A carboxylic acid anhydride such as acetic anhydride, is prepared from a carboxylate ester or a hydrocarbyl ether in processes comprising the use of a halide, carbon monoxide and a Group VIII noble metal.

Process for producing the center electrode of spark plug

Abstract: A process for producing a center electrode for a spark plug comprises the following steps: providing a cylindrical electrode body of a less noble metal which is predominantly made of a nickel alloy or a composite thereof with a copper core, the electrode body having a concentric, smaller-diameter projection from the tip of the body; placing on the tip of the electrode body a disk which has a center hole into which the projection fits and which is made of a noble metal such as platinum or an alloy thereof; electrically welding the noble metal disk to the tip of the electrode body; and drawing and extruding the assembly to reduce its outside diameter so that the layer of the noble metal or alloy thereof covers at least the side wall of the part close to the tip of the electrode body.

Manufacture of noble metal/zeolite catalysts

Abstract: A simplified method of manufacture of noble metal/zeolite catalysts involves impregnation of the formed catalyst base with a solution of the noble metal and an ammonium salt. Catalysts having a highly uniform radial distribution of the noble metal are prepared.

Noble metal/Si(111) interfaces studied by MeV ion scattering

Abstract: The displacement‐sensitive MeV ion‐scattering measurement has been performed on Si(111) surfaces covered with Au and/or Ag evaporated at room temperature. For single metal depositions, the reactivity of Ag atoms with Si atoms was very low compared to Au. For sequential depositions of both Ag and Au, the reactivity of the system was dominated by the more reactive material Au while the onset of the Si displacement depends on the amount of both metals for 0.5–2.0 ML coverage of predeposited materials (1 ML=7.83×1014 atoms/cm2). No significant differences were observed between Au/Si(111) 7×7 and Au‐stabilized 3×1 surfaces for subsequent Ag depositions. The mechanism of the reaction between the noble metal and Si atoms is discussed in terms of current models.

Recovery of silver and mercury from COD samples by iron cementation

Abstract: Cementation experiments were conducted on solutions containing mercury and silver and on actual wastes from chemical oxygen demand to assess mercury and silver recovery with iron as the reductant. Reaction order, reaction rate, removal efficiency, and stoichiometry of the reaction were evaluated. Reactions were half-order with respect to the noble ion concentration. The ratio of iron dissolved to noble metal removed indicated that the amount of iron used in the reactions was greater than the theoretical requirement for both metals. The relationship between the iron consumption ratio and initial noble metal concentration was investigated. Removal efficiencies of better than 99% for silver and mercury were readily attainable. The thickness of the mercury film deposited from single-solute mercury solutions was directly proportional to the ratio of initial mercury concentrations to reductant surface area. 13 references, 14 figures, 4 tables.

Process for the production of urethanes

Abstract: Urethanes are made by reacting a primary amine with carbon monoxide and a compound containing at least one hydroxyl group in the presence of an oxidizing agent and a catalyst system. The catalyst system is made up of (i) a noble metal and/or a noble metal compound of a metal of the Eighth Secondary Group of the Periodic System of Elements and (ii) an oxidizing quinoid and/or a compound capable of being converted to an oxidizing quinoid compound under the reaction conditions. The catalyst system may optionally include (iii) metal compounds of elements of the Third to Fifth Main Groups and/or First to Eighth Secondary Groups of the Periodic System of Elements and/or (iv) a tertiary amine. This reaction is generally carried out at a temperature of from 100° to 300° C. and at a pressure of from 5 to 500 bars. The product urethanes are useful in the production of isocyanates and pesticides.

Process for the hydrogenation of aromatic hydrocarbons

Abstract: A process for the hydrogenation of aromatic hydrocarbons contained in hydrocarbonaceous oil feed comprising at least about 15 wppm organic nitrogen compounds is provided in which the feed is contacted with hydrogen in a substantially sulfur-free environment in the presence of a catalyst comprising a Group VIII noble metal component, such as palladium, a Y-type crystalline aluminosilicate zeolite and a support such as alumina. When the hydrogenation activity of the catalyst decreases, the partially deactivated catalyst is stripped with hydrogen periodically to increase the hydrogenation activity of the catalyst.

Chemical reactions at the noble and near‐noble metal/InP interfaces: Comparison to Si and GaAs

Abstract: The room‐temperature chemical reactions of noble (Cu, Ag, Au) and near‐noble transition (Ni, Pd) metals with the vacuum cleaved InP (110) surface have been studied with surface sensitive photoemission spectroscopies. It has been shown that the chemical reactions at these interfaces are closely similar to the reactions taking place on silicon substrates. In particular all metals that react strongly with Si to produce silicides (Cu, Ni, Pd) also form stable phosphides. This reaction is accompanied by phase segregation of metallic In. In addition, for Au (intermixing without a stable compound with P) and Ag (very weak reaction with substrate; growth of metallic Ag islands) the reactions with both InP and Si are qualitatively identical. It has been found that for GaAs the reactions with noble and near‐noble metals, though weaker than for InP, follow the same pattern.

Zeolite catalyst and process for using said catalyst

Abstract: OF THE DISCLOSURE A class of catalysts which exhibit superior activity maintenance in dehydrocyclization reactions are defined as a type L zeolite having exchangeable cations of which at least 75% are selected from Group IA and calcium and barium cations and containing well dispersed particles of at least one Group VIII noble metal where at least 90% of the noble metal thereof is dispersed in the form of particles having a diameter less than 7 .ANG.. The catalysts may also be identified as type L zeolites loaded with at least one Group VIII noble metal which have a terminal cracking index (as a measure of production of pentanes versus butanes from hexane) of at least 1.5.

A thin film electroluminescent display device

Abstract: An improved dark field material for use in a thin film electroluminescent display device that typically includes a transparent electrode layer, a segmented electrode layer and an electroluminescent phosphor layer between the electrode layers. The improved dark field layer is of a composition of a dielectric material such as the preferred magnesium oxide and a noble metal, which is preferably gold co-evaporated by way of an electron beam deposition technique. The preferred range of noble metal by volume is 6%-101%. By varying the noble metal content within this range, there is provided control of the operating temperature of the electroluminescent display device.

Reactivation of noble metal-containing zeolite catalyst materials

Abstract: A process is described for rejuvenating a coke-deactivated noble metal-containing zeolite catalyst material which comprises sulfiding the deactivated catalyst material by contacting with a sulfiding agent such as hydrogen sulfide-containing gas, removing coke from the sulfided catalyst by contacting the catalyst with oxygen in the presence of sulfur dioxide, and thereafter reducing the catalyst in the presence of a reducing agent such as hydrogen. The process permits catalyst reactivation by burning off coke from the catalyst while avoiding excessive agglomeration of the noble metals thereon.

Process for recovering noble metals belonging to group VIII of the Periodic System of the elements from a contaminated catalyst solution originating from the carbonylation of methyl acetate and/or dimethylether

Abstract: In this process for recovering noble metals of group VIII from a contaminated catalyst solution originating from the carbonylation of methyl acetate and/or dimethylether (the catalyst solution containing carbonyl complexes of these noble metals, organic or inorganic promoters, undistillable organic contaminants as well as volatiles) the volatiles are distillatively removed from the catalyst solution and the remaining distillation residue is water-treated, whereby the noble metal/carbonyl-complex is precipitated together with the organic contaminants and is separated from the aqueous phase, while the promotor is dissolved and recovered in conventional manner. The noble metals are then set free in elemental form by subjecting the noble metal/carbonyl-complex separated and contaminated with organic polymers at temperatures of 150° to 300° C. to treatment with an ethyleneglycoldialkylether solvent of the formula R(--OCH2 --CH2)n --OR, in which n stands for a number of from 1 to 4 and R stands for identical or different alkyl groups having from 1 to 6 carbon atoms. The noble metal can then be recovered by filtration, and the solvent can be freed of organic contaminants by distillation.

Method for increasing fuel efficiency

Abstract: By contacting a combustible fluid fuels with a metallic medium, such as metallized pellets, the fuel efficiency of the fuel can be increased. The metallic medium is maintained at a temperature sufficiently low so as to not alter the fluid phase of the fuel, e.g. if liquid, it remains liquid. The metallic medium is, preferably, a noble metal, such as platinum.

Plating method of metal dispersed with particles

Abstract: PURPOSE:To form a noble metal plating layer having various excellent characteristics at a low cost in the stage of forming a plating layer of noble metals or an alloy contg. noble metals by dispersing and codepositing specific inorg. particles and metallic particles in the plating layer. CONSTITUTION:A plating layer of noble metals such as Pd, Au, In, Ru or the like or a plating layer of their alloy is formed on the electrical contact part of a relay, switch, contact point, etc. in order to improve the resistance to corrosion and wear, high conductivity and the resistance to wear by arc. Hard inorg. particles or lubricative inorg. particles of caribide, oxide, boride, nitride, etc. are suspended in a concn. of 5-500g/l with grain sizes as fine as 0.01-10mu in the plating bath of the above-mentioned noble metal or noble metal alloy and further particles of about the same degree as the metal composing the plating bath are suspended in an amt. of 1/20-1/2 of the amt. of the inorg. particles, then plating is performed. The noble metal plating layer dispersed and codeposited uniformly with the inorg. particles and metallic particles is obtd. at a low cost.