Results 131 to 140 of about 595 (174)

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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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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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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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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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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Crystal Distortion in Copper Ferrite-Chromite Series

Journal of the Physical Society of Japan, 1961
The cation distributions in copper ferrite-chromite series and the copper ferrite quenched from high temperatures are measured by X-ray diffraction method. The lattice parameters are also measured as a function of chromium ion content and of temperature.
Haruyuki Ohnishi, Teruo Teranishi
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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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Properties of Copper Chromite Catalysts in Hydrogenation Reactions

Journal of Catalysis, 1997
Abstract A pretreatment involving a 4-h reduction under H2at 573 K, compared to either 473 or 673 K, gave the highest specific activity for furfural and crotonaldehyde hydrogenation over an unpromoted copper chromite catalyst. Both H2and CO chemisorption declined monotonically with increasing reduction temperature, but turnover frequencies also ...
R. Rao, A. Dandekar, R.T.K. Baker, M.A. Vannice   +3 more
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