Results 171 to 180 of about 7,842 (218)

Electrical transport in copper chromite catalyst

Journal of Materials Science, 1984
The electrical conductivity, σ, and thermoelectric power, S, of copper chromite (CuCr2O4) are reported in the temperature range 295 to 815 K. A break (TB) in the slope of the plot of log σ against T−1 was observed around 556 K. Apart from this break, the curves are linear, and their slopes correspond to activation energies of 0.60 eV (TB 556 K).
B. N. Tiwari, P. N. Ojha, C. S. Shukla
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Study of copper chromite catalysts, III. Structure and catalytic activity of copper chromite catalyst in reductive alkylation reaction

Reaction Kinetics and Catalysis Letters, 1986
The catalytic activity of copper chromite catalysts prepared by thermal decomposition reaction of basic copper(II) ammonium chromate, CuCrO4[Cu(OH)2]0.17−(NH4OH)0.78, and copper(II) chromate CuCrO4, has been studied. The catalysts with highly disordered structure, prepared from basic copper(II) ammonium chromate at 270–320 °C, show the highest ...
F. Hanic, G. Plesch, P. Dolezel, J. Ovecková   +3 more
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Structure and reactivity of copper-zinc-cadmium chromite catalysts

Applied Catalysis A: General, 1995
Abstract Different mixed oxides containing Cu, Zn, Cd and Cr were obtained by heating hydroxycarbonate precursors at various temperatures and in different atmospheres, and characterized by using X-ray diffraction (XRD), infrared, diffuse reflectance spectroscopy, thermogravimetry, and BET and copper surface area analysis.
CASTIGLIONI GL, VACCARI A, FIERRO G, INVERSI M, LO JACONO M, MINELLI M, PETTITI I, PORTA P, GAZZANO M   +8 more
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Crystal and magnetic structure of copper chromite

Acta Crystallographica, 1957
Copper chromite, CuCr~O 4, is a tetragonally distorted normal spinel with a c/a ratio, as referred to a face-centered unit cell, of about 0.91. A structure which is physically reasonable, belonging to the space group D~-I42d, is based on an environment for the copper ions which is distorted from a tetr~hedron toward a square, and also slightly rotated ...
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Characterization of copper chromite catalysts for methanol dehydrogenation

Applied Catalysis, 1984
Abstract Copper chromite catalysts have been characterised by total and metal surface areas. X-ray powder diffraction, thermal gravimetric analysis and selective extraction of copper oxide in order to investigate the nature of the active catalyst for methanol dehydrogenation.
S.P. Tonner, M.S. Wainright, D.L. Trimm, N.W. Cant   +3 more
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Sintering of lanthanum chromite doped with zinc or copper

Journal of Materials Science Letters, 1988
La substitution de Zn ou Cu a Cr dans LaCrO 3 permet l'obtention de ceramiques denses sans controle de la pression d'oxygene lors du ...
Shinsuke Hayashi, Kenji Fukaya, Hajime Saito   +2 more
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A study of the preactivation of a copper chromite catalyst

Catalysis Letters, 1994
Copper chromite was studied for the reductive alkylation of aniline with acetone to N-isopropylaniline as a function of the catalyst prereduction conditions. In order to optimize prereduction conditions the catalyst was reduced in an atmosphere of hydrogen at different temperatures: 100, 150, 200, 250, 300, 350, 400 and 450°C and for different ...
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The nature of hydrogen stabilization in the reduced copper chromites

Journal of Molecular Catalysis A: Chemical, 1996
Abstract In situ powder X-ray and neutron diffraction showed that copper chromite retains its spinel structure (space group Fd3m, a = 8.348(3) A ) in hydrogen at 320°C. The spinel has a copper ion deficiency and is stabilized by the dissolved hydrogen.
L.M. Plyasova, L.P. Solovyeva, T.A. Krieger, O.V. Makarova, T.M. Yurieva   +4 more
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Methane combustion over copper chromite catalysts

Catalysis Letters, 1997
A study of the activity and durability of two different copper chromite catalysts in methane combustion is presented. The catalysts, a massive (CAT-E) and a supported (CAT-I) copper chromite, were characterized by different techniques in order to investigate morphological properties (N2 adsorption), crystalline structure (X-ray diffraction, XRD) and ...
G. Comino, A. Gervasini, V. Ragaini, Z. Ismagilov   +3 more
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Nanometer size copper particles in copper chromite catalysts

1995
Publisher Summary It is difficult to obtain copper in atomic state on the surface of an oxide catalyst. Therefore, the task of achieving metallic copper with a large surface area becomes crucial. Highly dispersed copper can be obtained on the surface via the reduction of copper-containing oxides.
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