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Showing papers on "Nickel published in 1972"


Journal ArticleDOI
TL;DR: In the presence of a nickel catalyst, acetylene decomposed to form carbonaceous solids with filamentary, amorphous, or laminar form as discussed by the authors, and parameters controlling the type of deposit have been established.

1,142 citations



Journal ArticleDOI
J. H. Sinfelt1, J.L. Carter1, D.J.C. Yates1
TL;DR: In this article, the effect of adding copper to nickel was investigated for the hydrogenolysis of ethane to methane and the dehydrogenation of cyclohexane to benzene over a series of copper-nickel alloys.

585 citations


Journal ArticleDOI
TL;DR: A series of alcohols and amines have been oxidised at oxide-covered nickel, silver, copper, and cobalt anodes in aqueous alkaline solutions as mentioned in this paper, and it was shown that the mechanism of these oxidations involves hydrogen abstraction from the substrate by an oxide species rather than direct electron transfer to the anode.
Abstract: A series of alcohols and amines have been oxidised at oxide-covered nickel, silver, copper, and cobalt anodes in aqueous alkaline solutions. The kinetics of these electrode processes have been studied and it is shown that the mechanism of these oxidations involves hydrogen abstraction from the substrate by an oxide species rather than direct electron transfer to the anode. The mechanism put forward is compared with those commonly suggested for the chemical reactions of transition-metal oxides and for heterogeneous catalysis.

313 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that the scale-forming reaction of Ni-20 wt. % Cr2O3 scales on dispersion-free systems must involve shortcircuit diffusion of chromium through the scale, and that it seems probable that an effect of the dispersion must be to retard or eliminate this short-circuit process.
Abstract: Alloys of Ni-20 wt. % Cr containing 3 vol. % of a dispersed oxide phase have been prepared by a mechanical alloying method and oxidized in oxygen at 100 Torr in the temperature range of 900 to 1200°C. It appears that the dispersed oxide has four distinct effects on the oxidation: (1) the selective oxidation of chromium to form a continuous protective Cr2O3scale is promoted; (2) the rate of growth of Cr2O3is reduced compared with particle-free alloys; (3) the adhesion of the Cr2O3is greatly improved; and (4)the scale-forming reaction appears to be at the scale-metal interface in alloys containing a dispersion, but at the scale-oxygen interface in alloys without a dispersion. It appears that the nature of the dispersed oxide is not important, since very similar effects can be obtained with ThO2,Y2O3,and CeO2dispersions. It is demonstrated that a logical deduction from this evidence is that the growth of Cr2O3scales on dispersion-free systems must involve short-circuit diffusion of chromium through the scale, and that it seems probable that an effect of the dispersion must be to retard or eliminate this short-circuit process. It is suggested that the oxide particles act as nucleation centers for the oxide, thus reducing the oxide grain size; and it is shown that this simple hypothesis is sufficient to explain a number of the experimental observations.

266 citations




Journal ArticleDOI
K.S. Kim1, R.E. Davis1
TL;DR: In this paper, the nickel photoelectron spectra of NiO are attributed to arise from multiples coupling and monopole charge transfer transition (O 2 pe g bo → Ni 3 de g ao ) accompanying primary photoemission.

222 citations



Journal ArticleDOI
TL;DR: In this article, the lattice parameter and density results have been obtained for alloys in the β-NiAl and 6-Ni2Al3 phase fields of the nickel-aluminium system.
Abstract: New lattice parameter and density results have been obtained for alloys in the β-NiAl and 6-Ni2Al3 phase fields of the nickel–aluminium system. The lattice parameter of the β-NiAl phase (CsCl-type) falls linearly from 2.8870 A at 50 at.% Ni to 2.8618 A at 66. at.% Ni, with 2.00 atoms per unit cell. On the other hand, the lattice parameter on the Al-rich side of NiAl falls linearly from 2.8870 A to 2.8652 A, while the number of atoms per unit cell falls from 2.00 to 1.817 by the creation of vacancies in normally nickel sites. The trigonal 6-Ni2Al3 phase-structure, which is essentially an extension of cubic β-NiAl, but with every third plane of nickel atoms perpendicular to the trigonal axis missing, shows a minimum in the a and c spacings at stoichiometric Ni2Al3. Density measurements indicate that the vacancies formed by the missing planes are progressively filled as nickel is added to Ni2Al3, but that a substitutional solid solution is formed on the aluminium-rich side of stoichiometric Ni2Al3 with aluminium replacing nickel atom by atom. In the NiAl phase, the number of valence electrons increases from 2.28 per unit cell at 61.9 at.% Ni to 3.00 at stoichiometric NiAl, and remains constant at 3.00 as the vacancies form until Ni2Al3 is reached, at which stage the number of vacancies will have reached a maximum when there are only 1.67 atoms per pseudo-cubic cell. The number of electrons per pseudo-cubic unit cell then begins to rise and reaches the phase boundary value of 3.12 at 37.6 at.% Ni.

198 citations


Journal ArticleDOI
TL;DR: In this paper, the equilibria of the decomposition reactions of carbon monoxide and methane were studied in the temperature range 450-700 °C on various nickel catalysts by means of a thermogravimetric apparatus.

Journal ArticleDOI
TL;DR: In this article, a cyclopentane-deuterium exchange has been followed on nickel and some nickel-copper alloys in the temperature range 200-430 °K.



Journal ArticleDOI
TL;DR: In this paper, the syntheses and properties of copper(II) and nickel (II) complexes of N,N′-alkylenebis(3-formyl-5-methylsalicylaldimine (alkylene=ethylene, propylene, or trimethylene) are described.
Abstract: The syntheses and properties of copper(II) and nickel(II) complexes of N,N′-alkylenebis(3-formyl-5-methylsalicylaldimine (alkylene=ethylene, propylene, or trimethylene) are described. By the reaction of these complexes with other alkylenediamines (ethylenediamine or trimethylenediamine), mononuclear copper(II) and nickel(II) complexes of new N4O2-type macrocycles have been synthesized. These complexes react with additional copper(II) or nickel(II) ions to form binuclear copper(II) or nickel(II) complexes. The geometries and properties of these new complexes are discussed.

Book ChapterDOI
R. Van Hardeveld1, F. Hartog1
TL;DR: In this paper, the effect of the metal particle size on the properties of a metal-on-carrier catalyst was discussed, and infrared spectra were recorded with a Grubb-Parson single-beam grating spectrometer provided with a GS 4-type monochromator.
Abstract: Publisher Summary This chapter discusses the effect of the metal particle size on the properties of a metal-on-carrier catalyst. To relate the adsorptive and catalytic properties of metal crystals to the crystal size, the structure of the crystal surface on an atomic scale must be known. This information is obtained from studies on crystal models. A surface atom has a smaller number of nearest neighbors than an atom in the interior of the crystal. The chapter illustrates the infrared studies on the adsorption of N2, CO, and CO2. The infrared spectra were recorded with a Grubb–Parson single-beam grating spectrometer provided with a GS 4-type monochromator. From thermodynamic considerations, it is evident that bulk nickel cannot be oxidized by CO2. In addition, the reaction of benzene with deuterium is an excellent means for studying the influence of the particle size on the catalytic activity.


Journal ArticleDOI
TL;DR: In this paper, an Extended Huckel MO (EHMO) method was used to calculate the adsorption energy of a hydrogen atom over a surface nickel atom, which was shown to be more favorable than adsorbing in some surface holes.

Journal ArticleDOI
TL;DR: In this article, the authors measured the oxygen uptake of clean nickel from 24° to 450°C at oxygen pressures of. Ultra high vacuum techniques made it possible to start oxidation on specimens free of oxide and surface impurities such as C, Si, and S. This was followed by slower oxidation obeying a logarithmic rate law over the thickness range 8-30Aa.
Abstract: The oxidation of "clean" nickel has been investigated from 24° to 450°C at oxygen pressures of . Ultra‐high vacuum techniques made it possible to start oxidation on specimens free of oxide and surface impurities such as C, Si, and S. Oxygen uptake was measured manometrically with a capacitance gauge of submonolayer sensitivity. Initial rapid oxygen adsorption (and place exchange) on nickel was followed by slower oxidation obeying a logarithmic rate law over the thickness range 8–30Aa. Growth of thicker films was in accord with a parabolic rate law, transport through the oxide occurring predominantly via easy diffusion paths. The value of 41 kcal·mole−1 calculated from an Arrhenius plot of the parabolic rate constants from 300° to 450°C is an approximate measure of the activation energy for growth via leakage paths. A p1/6 dependence of the parabolic growth rate on oxygen pressure was found at 450°C.


Journal ArticleDOI
TL;DR: In this article, the graphite atomizer has been evaluated for direct injection analysis of sea water for trace transition metals and was found to be impossible due to the scattering interference of the major salts.

Journal ArticleDOI
TL;DR: In this article, the potential dependence of reaction product composition has been studied on high purity binary Cu-Ni alloys (10 − 40%Ni) in 0·5M sodium chloride solution at 25°C.

Journal ArticleDOI
TL;DR: In this paper, the adsorption energy, Arrhenius preexponential factor and sticking coefficient have been determined for surface hydrogen populations less than 1013 atoms/cm2, the values obtained being 22.7 kcal/mole, 2×10−1 cm2 · sec−1, and 0.1, respectively.
Abstract: The adsorption of hydrogen on the (111) plane of nickel at room temperature has been investigated using the technique of flash desorption spectroscopy. The residual CO partial pressure has been reduced below 1 × 10−11 torr to minimize the effect of H2 and CO coadsorption. The experimental apparatus and crystal cleaning procedure are described. Hydrogen was observed to desorb in a single pressure burst for all the experimental conditions examined. Four techniques have been used to analyze the experimental results and a coherent picture emerges for low surface populations. The adsorption energy, Arrhenius preexponential factor and sticking coefficient have been determined for surface hydrogen populations less than 1013 atoms/cm2, the values obtained being 22.7 kcal/mole, 2×10−1 cm2 atoms−1 · sec−1, and 0.1, respectively. Furthermore it is shown that the adsorption energy is constant at low coverages. For surface populations greater than 1013 atoms/cm2, we have been able to reproduce the desorption spectra with a model in which either the adsorption energy decreased with adsorbed population or the pre‐exponential factor increased with population. It is not possible to distinguish between the two possibilities. Such a model does not however describe very well the observed adsorption kinetics. We have proposed that this discrepancy may be due to diffusion of hydrogen into the nickel when the crystal is heated.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the sorption of oxygen on the (110) face of a nickel single crystal and obtained the spectra obtained by varying the angle of incidence relative to the surface and the crystal orientation, can be explained by the assumption that in the case of the (2×1) structure every second place in the top [110] rows of Ni is occupied by an oxygen atom.
Abstract: In an experiment which combines low energy noble gas ion backscattering with LEED the sorption of oxygen on the (110) face of a nickel single crystal is investigated. The energy of the backscattered He+ ions is governed by binary collisions whereas the intensity of the spectrum is given by the cross sections, the concentration of surface atoms, the neutralization probabilities and the geometry. The spectra obtained by varying the angle of incidence relative to the surface and the crystal orientation, can be explained by the assumption that in the case of the (2×1) structure every second place in the top [110] rows of Ni is occupied by an oxygen atom. From a shadow effect observed at small angles of incidence it can be estimated that the adsorbed oxygen protrudes beyond the plane of the Ni atoms by about 0.4–0.8 A.



Journal ArticleDOI
TL;DR: In this paper, the valence bands of Cu, Ag and Ni have been obtained by X-ray photoemission spectroscopy (XPS) with a resolution of ≈ 0.5 eV.

Journal ArticleDOI
01 Aug 1972-Geoderma
TL;DR: In this article, the results are consistent with the prediction of crystal field theory, that elements with higher crystal field stabilization energies will displace manganite from the surface layers of the manganese oxides.


Journal ArticleDOI
TL;DR: In this paper, the defect structure of cobalt and nickel oxides is investigated and the concentrations and diffusion coefficients of the major defects in these oxides are determined as functions of temperature and oxygen pressure.
Abstract: Starting from a general model for the defect structure of nickel and cobalt oxides, the concentrations and diffusion coefficients of the major defects in these oxides are determined as functions of temperature and oxygen pressure. At the higher oxygen pressures, the majority of cation defects are mononegative metal ion vacancies while at lower oxygen pressures appreciable concentrations of dinegative metal ion vacancies are present. It is shown that it is highly probable that the onion defects are dipositive oxygen vacancies. However, these are minority defects over the whole stability range of the oxides. It is not possible with the methods discussed here to determine their individual concentrations and diffusion coefficients. On the basis of this defect structure, a model for the oxidation of Co and Ni is proposed; the deductions from this model are compared with experimental results and good agreement is observed. It is shown that more than one type of defect contributes to the total transport through the oxide. For cobalt, these are mono- and dinegative metal ion vacancies; for nickel, dipositive oxygen vacancies also make a significant contribution.