Showing papers on "Noble metal published in 1973"
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TL;DR: In this paper, the charge required to oxidize the strongly bound intermediate on Pt electrodes in 1 M H2SO4 is determined from sweep measurements extrapolated to infinite speed, and from the oxidation of the intermediate in the absence of bulk reaction using a dipping technique.
551 citations
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TL;DR: In this article, the dual path mechanism for HCOOH oxidation has been verified and the ability of Pt, Rh, Ir and Au to adsorb reaction intermediates in varying degrees has been demonstrated.
398 citations
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TL;DR: In this paper, the authors reviewed recent work on the oxidation of formic acid on noble metal electrodes in aqueous solution at room temperature and concluded that detailed studies of the mechanism are necessary for each electrode material.
310 citations
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TL;DR: In this paper, a comparative study of the infrared spectra of reaction intermediates and chemisorbed species during the reaction of NO + CO over Pt, Pd, Rh, Ir, and Ru-on-alumina catalysts at elevated temperatures has been made.
179 citations
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110 citations
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TL;DR: In this paper, the lattice constants of isostructural series show a trend which also is known for the radii of the actinide elements, and the preparation of alloy phases of some other transition and main group elements, e.g., Zr, Hf, Nb, Ta, MgBa, are reported.
77 citations
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TL;DR: The discovery of this isocyanate species suggests a new mechanistic pathway to the ammonia formed during catalytic reduction of nitrogen oxides in automobile exhaust.
Abstract: Isocyanate species have been detected on the surface of noble metal catalysts during the reactions of carbon monoxide with nitric oxide. The intensity of the surface isocyanate infrared band correlates with the known ammonia-forming tendencies among the noble metals. The discovery of this isocyanate species suggests a new mechanistic pathway to the ammonia formed during catalytic reduction of nitrogen oxides in automobile exhaust.
70 citations
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01 Jun 1973TL;DR: Compositions of a Group VIII noble metal, tin and an inorganic, solid, refractory oxide carrier have excellent dehydrogenation activities and little or no isomerization and cracking activities as mentioned in this paper.
Abstract: Composites of a Group VIII noble metal, tin and an inorganic, solid, refractory oxide carrier have excellent dehydrogenation activities and little or no isomerization and cracking activities.
60 citations
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TL;DR: In this paper, the authors showed that the active surface in chemisorption is confined to a few atomic layers, consistent with the known immiscibility of the component metals.
59 citations
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TL;DR: In this article, the valence bands of noble-metal alloys were studied using Al K α-radiation and the results showed that in the absence of surface contamination the alloys exhibit more intense spectra with sharper features than those observed for previously studied bulk samples.
46 citations
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06 Aug 1973TL;DR: In this paper, a method of coating a gas turbine engine alloy substrate comprising depositing a rare earth and aluminum-containing alloy initial layer to a thickness sufficient to produce and maintain an adherent irregular aluminum oxide was proposed.
Abstract: A method of coating a gas turbine engine alloy substrate comprising depositing a rare earth and aluminum-containing alloy initial layer to a thickness sufficient to produce and maintain an adherent irregular aluminum oxide, mechanically working the surface of the initial layer to induce irregularity and angular topography in the aluminum oxide to be produced, oxidizing the initial layer to produce a sufficiently thick and irregular aluminum oxide layer to establish mechanical adherence of a noble metal layer and prevent alloying between the initial layer and the noble metal layer, depositing a noble metal layer on the oxidized layer to a thickness of approximately 0.1-0.2 mils and oxidatively treating the coated substrate to cause additional growth of the oxide layer to metallurgically insulate the noble metal layer from the substrate and the initial metal layer.
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TL;DR: In this paper, the effect of 5d character on the crystalline electric field in noble metal rare earth alloys and in pure rare earths has been investigated and the change in sign of the fourth order CEF coefficient in the noble metal alloys can be interpreted in terms of this d character.
Abstract: The effect of 5d character on the crystalline electric field in noble metal rare earth alloys and in pure rare earths has been investigated. The change in sign of the fourth order CEF coefficient in the noble metal alloys can be interpreted in terms of this d character. From symmetry this d like component has no effect on the sixth order coefficients whose varying magnitude in these alloys can be explained using the f like contribution. In the pure rare earth metals it is likely that d character will predominate.
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10 Jan 1973TL;DR: In this paper, a stable aprotic solvent (e.g. propylene carbonate) and at least 1 stable conducting salt are used to prevent oxalate-anions formed at the cathode.
Abstract: is electrochemically reduced, using an electrolytic cel contng. a stable aprotic solvent (e.g. propylene carbonate) and at least 1 stable conducting salt (e.g. a tetra-1-4C-alkyl-ammonium carbonate) dissolved therein, the cell comprising a cathode (e.g. a Cr-Ni-steel) which consists of an electrical conductor that does not chemisorb the CO2, and of an anode (e.g. a noble metal such as Pt). The cathode is kept free of reducible cpds. and the anode is kept free of oxalate-anions formed at the cathode. This may be achieved by interposing ion exchange membranes. Electro-chemical reduction of CO2 in protic solvents (water) has in the past resulted in the formation of formic acid. The prodn. of oxalic acid by the claimed process has been made possible by using suitable aprotic solvents, conducting salt and material for the electrodes.
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18 Sep 1973TL;DR: A fuel cell electrode catalyst, adapted for application to a carbon fiber support mat substrate, is formed by the repetitive process of: mixing the powder with a dilute solution of the salt so as to form a slurry, the slurry then being concentrated and dried followed by the decomposition of salt to form partial product which is then used in place of the carrier powder in a repetition of the process until the desired concentration of catalyst is achieved as discussed by the authors.
Abstract: A fuel cell electrode catalyst, adapted for application to a carbon fiber support mat substrate to form a fuel cell electrode, comprising small crystals of noble metal fuel cell catalyst specie, such as platinum, deposited on discrete particles of an inert carrier or support such as carbon powder, is formed by the repetitive process of: mixing the powder with a dilute solution of the salt so as to form a slurry, the slurry then being concentrated and dried followed by the decomposition of the salt to form a partial product which is then used in place of the carrier powder in a repetition of the process until the desired concentration of catalyst is achieved. Usage of a low concentration of catalyst salt results in a smaller crystallite, which yields a higher surface area of catalyst, for a more active electrode that provides an improved current/voltage performance characteristic at a lower cost.
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08 Jan 1973TL;DR: In this paper, the ratio of a nickel or nickel-containing alloy to a noble metal is up to 1/1 (by weight), where the ratio is defined as the ratio between the two components of the alloy.
Abstract: Metallizations for formation of conductors on substrates, comprising (1) nickel or nickel-containing base metal alloys, and (2) noble metals, e.g., palladium, palladium/gold, platinum/palladium/gold, and palladium/silver, wherein the ratio of nickel or nickel-containing alloy to noble metal is up to 1/1 (by weight). The metallization are used as conductors on ceramic substrates and for ceramic capacitors.
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14 Feb 1973TL;DR: In this paper, a process for depositing a noble metal catalyst on an oxide support material comprising contacting the support material with an alkaline solution of complex noble metal-amine cations under prescribed pH conditions is disclosed.
Abstract: A process for depositing a noble metal catalyst on an oxide support material comprising contacting the support material with an alkaline solution of complex noble metal-amine cations under prescribed pH conditions is disclosed. The process is particularly suitable for depositing catalysts on monolithic honeycomb support structures because the catalyst dispersions produced thereby are extremely uniform on the interior channel walls of the structure.
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10 Sep 1973TL;DR: In this article, a thin catalyzed gas electrode for fuel cells comprising a porous wet proofed conductive substrate having a first waterrepellent porous active conductive layer over which is a surfacedeposited noble metal catalyst in an amount of at least about 0.5 mg/cm2, and a process for producing such an electrode.
Abstract: A thin catalyzed gas electrode for fuel cells comprising a porous wet proofed conductive substrate having a first waterrepellent porous active conductive layer over which is a surfacedeposited noble metal catalyst in an amount of at least about 0.5 mg/cm2, and a process for producing such an electrode.
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TL;DR: In this article, crystal field studies in a variety of 4 f and some 5 f electron-systems reveal a correlation between crystal field splittings, i.e. sign and charge strength of simple ligands and their electronegativities.
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29 Nov 1973
TL;DR: An improved anode structure for a chlor-alkali type diaphragm cell was proposed in this paper, where the anode is a porous, valve metal, e.g., titanium, anode having on one side a coating of a noble metal or noble metal oxide and on the uncoated side a membrane composed essentially of a cation-active permselective material which was substantially impervious to liquids and gases.
Abstract: An improved anode structure for a chlor-alkali type diaphragm cell wherein the anode is a porous, valve metal, e.g., titanium, anode having on one side a coating of a noble metal or noble metal oxide and on the uncoated side a membrane composed essentially of a cation-active permselective material which is substantially impervious to liquids and gases. The membrane covered surface is disposed spaced from but facing the cathode member. Anodes of this improved structure give minimum cell voltage and a surprisingly reduced consumption rate of the noble metal or oxide coating.
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25 Jun 1973
TL;DR: In this article, a colloidal catalyst metal-free acid liquid solution of a soluble, Lewis base-modified noble metal-tin halide complex is used to render surfaces intended to be electrolessly metal plated.
Abstract: Surfaces intended to be electrolessly metal plated are treated with a colloidal catalyst metal-free acid liquid solution of a soluble, Lewis base-modified noble metal-tin halide complex until the surface is rendered catalytic. The noble metal of the complex is a noble metal which is catalytic to the deposition of the metal destined to be electrolessly plated on the surface.
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29 Nov 1973
TL;DR: In this article, a noble metal catalysts are prepared by supporting the noble metal onto a refractory porous inorganic support from an aqueous medium containing a metal or a compound thereof in the presence of a nonionic surface active agent of poly(oxyethylene) type having an average molecular weight of at least 500.
Abstract: Noble metal catalysts are prepared by supporting a noble metal onto a refractory porous inorganic support from an aqueous medium containing a noble metal or a compound thereof in the presence of a nonionic surface active agent of poly(oxyethylene) type having an average molecular weight of at least 500 and subjecting the so treated support to activation.
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12 Mar 1973
TL;DR: In this article, the authors described the preparation of hydrophilic, semi-permeable film membranes having an increase in pores and containing complex-forming metals, which can be useful for separating a component, e.g. an aliphatically-unsaturated hydrocarbon, from mixtures by the combined use of liquid barrier permeation and metal complexing techniques.
Abstract: There is described the preparation of hydrophilic, semi-permeable film membranes having an increase in pores and containing complex-forming metals. The films can be formed from solutions having film-forming material and pore-forming material dissolved in a solvent. The films can be useful for separating a component, e.g. an aliphatically-unsaturated hydrocarbon, from mixtures by the combined use of liquid barrier permeation and metal complexing techniques. The liquid barrier is at least partially within the hydrophilic film membrane during use, and the barrier contains complex-forming metal ions in aqueous solution. The metal ions may be, for example, noble metal, nickel, mercurous, cuprous or other metal ions, and mixtures of these metal ions, and the aqueous solution may contain other cations. The separation of ethylene from ethane and methane is of particular interest.
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24 Jul 1973TL;DR: In this article, the authors used a solution of palladium ions to cover the surface of the nickel surface and then applied strong nitric acid to the solution to increase the amount of surface deposition.
Abstract: Nickel with a surface deposit of palladium is useful as an exhaust gas catalyst. Palladium may be deposited by contacting nickel with a solution of palladium ions. More than one deposition can be used. If a first deposition is followed by contacting the nickel with strong nitric acid, a second palladium deposition will result in an increased amount of palladium on the nickel surface.
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08 Jan 1973
TL;DR: A multi-component catalyst composition prepared by combining (A) noble metal catalyst elements effective for oxidizing carbon monoxide and hydrocarbons with (B) catalyst elements ineffective for the same purpose but containing no noble metal is presented in this paper.
Abstract: A multi-component catalyst composition prepared by combining (A) noble metal catalyst elements effective for oxidizing carbon monoxide and hydrocarbons with (B) catalyst elements effective for the same purpose but containing no noble metal The multi-component catalyst composition is effective in purifying exhaust gases containing nitrogen oxides, carbon monoxide and hydrocarbons by converting these harmful components into harmless components
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09 Jul 1973TL;DR: In this paper, a method for melting glass laser compositions to provide glass laser rods with a minimum of noble metal inclusions and a minimum amount of dissolved noble metal content is presented, where the process comprises melting the laser glass in a platinum container in a controlled reducing atmosphere using a buffered gas mixture.
Abstract: This invention provides methods for melting glass laser compositions to provide glass laser rods with a minimum of noble metal inclusions and a minimum of dissolved noble metal content. The process comprises melting the laser glass in a platinum container in a controlled reducing atmosphere using a buffered gas mixture, such as CO2/CO in which the partial pressure of oxygen is at a minimum level that is equivalent to a range of about 10 8.6 to 10 38 atmospheres for a temperature range of about 981 DEG F. to 3,321 DEG F. for a silicate glass. A method also is provided for melting glass to make high-quality glass articles in a noble metal container or a lined container in which the container or the liner therefore has at least 50% by weight of platinum without any attack on the container by the unwanted formation of a noble metal alloy from the glass melt during melting. The method comprises heating molten glass in the platinum container, providing a reducing atmosphere in which the partial pressure of oxygen is no greater than about 10 3 atmospheres with a buffered gas mixture, and controlling the reducing atmosphere by maintaining the partial pressure of oxygen above the amount at which oxides of an element such as SiO2, Li2O and Na2O are reduced to the element such as Si, Li or Na, so that the element does not react with the platinum metal to form a platinum-Si alloy.
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14 Nov 1973TL;DR: In this article, a process for regenerating deactivated noble metal hydrogenation catalysts to restore their catalytic activity is described, where the process involves contacting a deactivated metal hydrogenization catalyst with a polar organic solvent, then contacting the solvent-treated catalyst with an aqueous ammonium hydroxide solution followed by contacting the ammonium hyroxidetreated catalyst with steam and an oxygen-containing gas at temperatures from about 250*C to the transition temperature of the catalyst crystal structure.
Abstract: This invention describes a process for regenerating deactivated noble metal hydrogenation catalysts to restore their catalytic activity The process involves contacting a deactivated noble metal hydrogenation catalyst with a polar organic solvent, then contacting the solvent-treated catalyst with an aqueous ammonium hydroxide solution followed by contacting the ammonium hydroxidetreated catalyst with steam and an oxygen-containing gas at temperatures from about 250*C to the transition temperature of the catalyst crystal structure whereby the catalytic activity of the catalyst is substantially improved