Showing papers on "Noble metal published in 1989"

New solid polymer electrolyte composites for water electrolysis

Abstract: A new procedure for the preparation of SPE-electrocatalyst composites has been developed. In this procedure, noble metal cationic species are chemically reduced within a solid polymer electrolyte. The metallic particles are not homogeneously distributed across the SPE thickness but predominate near its surfaces. The structure and the distribution of the precipitates, along the membrane thickness have been investigated by scanning electron microprobe analysis and transmission electron microscopy. Application to SPE water electrolysis has been performed using Nafion membranes and platinum-group electrocatalysts. The SPE-electrocatalyst composites prepared according to this new procedure present good electrochemical properties, low catalyst loadings, long-time stability and high energetic efficiencies.

A layered automotive catalytic composite

Abstract: This invention relates to a catalytic composite for treating an exhaust gas to minimize the hydrogen sulfide content thereof and comprising a first support which is a refractory inorganic oxide having dispersed thereon at least one noble metal component and having dispersed immediately thereon an overlayer comprising at least one oxygen storage component and optionally a second support which is a refractory inorganic oxide. The first support may be selected from the group consisting of alumina, silica, titania, zirconia and aluminosilicates with alumina being preferred. The noble metal component may be selected from the group consisting of platinum, palladium, rhodium, ruthenium and iridium. The oxygen storage component is an oxide of a metal which includes cerium, iron, nickel, cobalt lanthanium, neodymium, praseodymium, etc. and mixtures thereof. Cerium oxide is a preferred oxygen storage component. The second support may be selected from the group consisting of alumina, silica, titania, zirconia and aluminosilicates, with alumina preferred.

Zerovalent metal polymer composites. I. Metallized beads

Abstract: Binding of a noble metal salt, eg, PdCl to a functional ligand on a polymer surface, eg, amine, quaternary ammonium, sulphonic acid, followed by reduction to zerovalent state and subsequent reductive deposition of transition metal ions, such as copper, nickel, and cobalt, provides a sequence of events leading to controlled zerovalent metal polymer composites Metallization of submicron and larger beads are described Large amounts of metal can be incorporated The metallized beads retain the shape of the starting beads, even at high bonding of metal They adapt the properties of the metal, eg, magnetic properties The submicron particles are sensitive to hydrolysis Multicomponent systems, such as multimetallic beads, are provided by additive codeposition of metal ions, or by codeposition of metal and dye Direct deposition of metal to preimmobilized dye ligands is also possible, leading to magenta, cyan, or yellow metallic beads, with no adverse influence on the magnetic properties Further deposition of noble metals by subtractive deposition on active metal surfaces is also described Submicron latices can be immobilized by coating on polyester-based films, eg, KODAK ESTAR base, and then activated with palladium and metallized to form highly conductive film surfaces

A lanthanum containing catalyst for treating automotive exhaust gas.

Abstract: This invention relates to an improved catalytic composite for treating an exhaust gas comprising a first support which is a refractory inorganic oxide, having dispersed thereon at least one oxygen storage component and at least one noble metal component and having dispersed immediately thereon an overlayer comprising lanthanum oxide and optionally a second support which is a refractory inorganic oxide. The first and second support may be selected from the group consisting of alumina, silica, titania, zirconia and aluminosilicates with alumina being preferred. Additionally, the noble metal component may be selected from the group consisting of platinum, palladium, rhodium, ruthenium and iridium. The oxygen storage component is an oxide of a metal which includes cerium, iron, nickel, cobalt lanthanum, neodymium, praesodymium, etc. and mixtures thereof. This invention also relates to a process for treating automotive exhaust comprising contacting the exhaust with the catalytic composite described above. The catalytic composite shows improved activity, especially for eliminating NOx, after extensive durability testing and also minimizes the formation of H2S.

The importance of superficial (adatom) surface oxidation in the electrocatalytic behaviour of noble metals in aqueous media

Abstract: The conventional, activated chemisorption, model of electrocatalysis is unable to explain fully the surprisingly high level of activity of gold anodes in base for certain organic electrooxidation reactions or even the ability of platinum to catalyse certain oxygen insertion reactions, e.g. methanol or formaldehyde oxidation in acid, at low potentials (in the hydrogen or double layer region) where the surface is considered usually to be oxygen-free. It was demonstrated that such behaviour can be rationalized by postulating the involvement of a quite low coverage of hydrous oxide species, generated at low potential at adatom sites, which act as mediators or catalysts in many electrooxidation reactions. The converse situation was also shown to arise, i.e. the reduction of certain species, e.g. HNO3 or NO 3 − , which requires the involvment of adatoms, was shown to be inhibited as long as the latter existed in the oxidized, hydrous oxide, form. An appreciation of hydrous oxide electrochemistry was shown to be very useful in interpreting electrocatalytic effects at noble metal electrodes in aqueous media.

Corrosion-resistant coatings technology

Abstract: 1. Principles of Corrosion Protection by Coatings 2. Cathodic Control Protection by Sacrificial Metal Coatings 3. Anodic Control Protection by Noble Metal Coatings 4. EMF Control Protection by Noble Metal Coatings 5. Mixed Control Protection by Conversion Coatings 6. EMF Control Protection by Organic Coatings

Electro‐Oxidation of Formaldehyde on Thermally Prepared RuO2 and Other Noble Metal Oxides

Abstract: The electro‐oxidation of formaldehyde has been investigated at thermally prepared noble metal oxides, especially, in aqueous solution. Studies were carried out on thin layers of oxide supported on Ta or Ti, and on thin, Teflonbonded oxide layers attached to a glassy carbon rotating disk electrode. The catalytic activity of for oxidation was considerably greater than that of and . At , formaldehyde was observed to undergo oxidation to formate at potentials from ca. 0.75–1.25V vs. reference hydrogen electrode (RHE), and to carbonate at higher potentials. The results suggest that (and ) oxidation is mediated by higher valent states of the oxide metal ions electrogenerated at the electrode surface. Values of 10−3 cm s−1 (geometric electrode area based) and 10−6 cm s−1 (real area based) were estimated for the heterogeneous rate constant for oxidation at . The activity for oxidation is correlated with the catalytic activity of the oxides for the oxygen gas evolution reaction.

Method of making mixed metal oxide coated substrates

Abstract: In a reactive ion plating process utilizing radio frequency power, the rate of evaporation of a noble metal such as ruthenium or iridium, the rate of evaporation of a valve metal such as titanium, and the partial oxygen pressure are adjusted to produce electrically conductive mixed metal oxide ceramic coating on a valve metal substrate. The noble metal constitutes 10-20 percent of the metal atoms in the coating. The coated substrate can sustain 150 amperes per square meter of exposed coating surface in fresh water electrolyte for at least 20 hours, and preferably at least 75 hours, without an excessive increase in the voltage level required to maintain that current density.

Spectroscopic characterisation and photochemical behaviour of a titanium hydroxyperoxo compound

Abstract: In order to obtain more information about the generation of peroxide species during water photo-cleavage using M/TiO2(M = noble metal) systems in which an O2 evolution is normally not observed, a titanium hydroxyperoxo compound has been prepared by the reaction of TiCl4 with H2O2. The structure and the thermal behaviour of this compound have been examined using TG-MS, XRD and TPD techniques. XPS, i.r., e.s.r. and u.v.-visible reflectance spectroscopy have been used to characterise the types of peroxo species present in this sample. The photochemical decomposition of this compound, which leads to O2 evolution, has been studied compared to a TiO2(Degussa P25) sample. A model is proposed to explain the lack of O2 evolution during water photo-cleavage on M/TiO2 systems where peroxo species, similar to those observed in the titanium hydroxyperoxo compound, become stabilised against photodecomposition.

High-temperature three-way catalyst for treating automotive exhaust gases

Abstract: A three-way catalyst for use in treating automotive exhaust gases employs a delta alumina support which contains oxides of cerium plus barium and/or lanthanum, plus at least one Group VIII noble metal from the group consisting of platinum, palladium, rhodium, ruthenium and iridium.

Ternary alloy fuel cell catalysts and phosphoric acid fuel cell containing the catalysts

Abstract: A noble metal ternary alloy catalyst, which has increased mass activity and stability. This catalyst comprises a ternary alloy of platinum, iridium and a metal selected from the group consisting of iron, chromium, cobalt, nickel, vanadium, titanium and manganese.

Electrochemical machining with avoidance of erosion

Abstract: Metal workpieces for electrochemical machining, particularly those comprising titanium and/or aluminum, are protected from pitting by the application of an adherent conductive and protective coating comprising a compound of at least one noble metal selected from the group consisting of ruthenium, rhodium, palladium, iridium and platinum. Said coating protects the workpiece and also catalyzes oxidation of halide and/or water in the electrolyte, which competes successfully with oxidative erosion in the vicinity of faults in the protective coating. Other anodic elements, including clamping fixtures and auxiliary anodes, may also be coated.

A multilayered metallurgical structure for an electronic component

Abstract: Disclosed is a multilayered metallurgical structure for an electronic component. The structure includes a base metallurgy which includes one or more layers of chromium, titanium, zirconium, hafnium, niobium, molybdenum, tantalum, cooper and/or aluminum. Directly on the base metallurgy is a layer of cobalt. The structure may also include a layer of noble or relatively noble metal such as gold, platinum, palladium and/or tin directly on the cobalt.

Durability of Palladium Only Three-way Automotive Emisson Control Catalysts

Abstract: The noble metal palladium (Pd) has the capability of simultaneously converting significant quantities of HC, CO and NO/sub x/ in automotive exhaust Primary interests in using palladium-containing TWC catalysts are overall noble metal cost reduction, reduction in rhodium usage and important performance advantages Dynamometer aging experiments comparing palladium and platinum/rhodium catalysts were conducted under a variety of operating conditions Vehicle evaluation of these aged catalysts under US FTP-75, European ECE-15 and Japan 10-Mode conditions indicate that palladium-only TWC technology is vaiable for achieving high levels of three-way control Vehicle aging studies (25K miles) were also conducted The results of these studies are discussed in this work

Catalyst for purifying exhaust gases and preparation thereof

Abstract: The invention concerns a catalyst for oxidation of hydrocarbons and carbon monoxide and/or reduction of nitrogen oxides. The catalyst consists of a carrier body and on this a catalytical coating, which consists of a washcoat layer containing a support material with a high specific surface area, one or more metal oxides with a promoting effect and at least two catalytically active noble metals within the washcoat or on the washcoat. The catalytical coating consists of at least two washcoat layers containing different amounts of at least one noble metal, in such a way that at least one noble metal is concentrated to more than 50% by weight of its total amount to at least one of the layers and that at least two noble metals are contained together in at least one of the layers. The invention also concerns a process for the preparation of said catalyst in order to obtain said layers with different composition of noble metals. The invention also concerns the use of said catalyst for purification of exhaust gases from internal combustion engines.

Method of selectively providing a metal from the liquid phase on a substrate by means of a laser

Abstract: From a solution comprising a salt of a noble metal, for example Pd, and ammonia or amine a metal track is deposited on a substrate surface which may be an insulator, semiconductor or conductor, by means of a laser beam.

Catalyst for exhaust gas purification and method for producing the catalyst

Abstract: There is provided an improved catalyst for purifying exhaust gases comprising a carrier carrying alumina, zirconium oxide and a noble metal catalyst The improvement resides in the fact that the carrier carries the alumina as a layer having dispersed therein the zirconium oxide particles, the zirconium oxide particles carrying said noble metal catalyst The dispersibility of the noble metal catalytic component is thereby improved and the sintering prevention effect on the noble metal catalytic component by the zirconium oxide is effectively exhibited Thus, the heat-proof property of the catalyst is improved and the cooperation between the noble metal catalytic component and alumina is effectively enhanced, improving longevity of the catalyst

Control of nitrogen oxide (NOx) emissions by selective catalytic reduction with hydrogen over hydrophobic catalysts

Abstract: The selective catalytic reduction of NO x with H 2 over noble -metal catalysts supported on hydrophobic material has been studied for the control of NO x emission from simulated stationary sources. The activity of the noble metal catalysts was found to be in the order Pt>Pd-Ru>Pd>Ru>>Au. The presence of O 2 in the feed tends to decrease the NO x conversion. The control of reaction temperature is crucial to the catalyst selectivity due to the competitive reaction between H 2 and O 2 . Optimum reaction temperature and space velocity lead to the minimum hydrogen requirement

Heat-resistant noble metal catalyst and method of producing the same

Abstract: A heat-resistant noble metal catalyst having both of exceedingly superior heat-resistant property and a remarkable high activity at any temperature ranges of low, middle, and high, is provided having a heat-reistant noble metal catalyst consisting essentially of a composition having a formula A 1-z C z B x D u Al 12-y-u O 19- α, wherein A is at least one element selected from the group consisting of Ba, Ca and Sr, C is at least one element selected from the group consisting of K, Rb and rare earth elements, B is at least one element selected from the group consisting of Mn, Co, Fe, Ni, Cu and Cr, D is at least one element selected from the group consisting of Au, Ag and platinum group noble metals, z is a value in a range of 0-about 0.4, x is a value in a range of 0-about 4, y is a value in a range of x-2x, u is a value of not less than about 0.01, x+u is a value of not more than about 4, and α is a value which is determined by the values X, Y, Z and U of the respective elements, A, C, B and D and the values of x, y, z and u and is expressed as α=1-1/2{X-z(X-Y)+xZ+uU-3y-3u}. A method of producing such a catalyst is also provided.

Catalyst for purifying exhaust gases and preparation and use thereof

Abstract: The invention concerns a catalyst for oxidation of hydrocarbons and carbon monoxide and/or reduction of nitrogen oxides. The catalyst consists of a carrier body and on this a catalytical coating, which consists of a washcoat layer containing a support material with a high specific surface area, one or more metal oxides with a promoting effect and at least two catalytically active noble metals within the washcoat or on the washcoat. The catalytical coating consists of at least two washcoat layers containing different amounts of at least one noble metal, in such a way that at least one noble metal is concentrated to more than 50 % by weight of its total amount to at least one of the layers and that at least two noble metals are contained together in at least one of the layers. The invention also concerns a process for the prepa­ration of said catalyst in order to obtain said layers with different composition of noble metals. The invention also concerns the use of said catalyst for purification of exhaust gases from internal combustion engines.