Showing papers on "Cerium published in 1975"
75 citations
Patent•
16 Jul 1975
TL;DR: In this paper, a process for the oxidation of olefins to unsaturated aldehydes and acids using a catalyst containing iron, bismuth, molybdenum plus at least one of nickel, cobalt, magnesium, zinc, cadmium or calcium is described.
Abstract: The present invention is a process for the oxidation of olefins to unsaturated aldehydes and acids using a catalyst containing iron, bismuth, molybdenum plus at least one of nickel, cobalt, magnesium, zinc, cadmium or calcium and according to the invention, an element selected from germanium, cerium, thorium, manganese, niobium, chromium, praseodymium, yttrium, zirconium, ruthenium, gallium, tin, indium, copper, lanthanum, tantalum or tungsten. These catalysts may also contain certain elements that further enhance the desirability of the oxidation process.
60 citations
TL;DR: In this article, the external layers of some zeolite surfaces were studied using X-ray photoelectron spectroscopy (XPS) and it was shown that the (Si/Al) ratio of the external surface is roughly twice that of the bulk.
43 citations
TL;DR: In this paper, the authors investigated the contribution of conduction electron and hydrogen diffusion to the relaxation rate of PdH 0.7 and found that the difference between diffusion coefficients for pure metal and alloys containing 3% and 6% cerium, is less than 30% and concluded that the considerably higher hydrogen permeation rates in the alloys are due to differences in surface processes.
Abstract: Proton spin-lattice relaxation measurements have been carried out on β - PdH x and ( Pd - Ce ) H x in the temperature range 100–300 K and at resonance frequencies of 7, 11 and 47 MHz. Contributions to the relaxation rate due to conduction electrons and due to hydrogen diffusion are identified. Measurements on β-PdH 0.7 , undertaken both as a reference for the work on the alloys and also in an attempt to resolve an apparent discrepancy between earlier NMR and neutron scattering (Beg and Ross 1970) determinations of hydrogen diffusion rates, yield an activation energy for diffusion of 0.228 ± 0.010 eV for temperatures above 195 K; below 195 K interpretation of the data is uncertain. The relation with neutron scattering data is discussed. The difference between diffusion coefficients for the pure metal, and alloys containing 3% and 6% cerium, is less than 30% and it is concluded that the considerably higher hydrogen permeation rates in the alloys (Wise et al. , 1972) are due to differences in surface processes.
38 citations
TL;DR: In this paper, the preparation of seven cerium(IV) phosphates, six of which new compounds were described, were characterized by means of analytical, thermal, i.r., and X-ray methods.
31 citations
TL;DR: In this article, the radiation-induced optical loss in both the visible and near-infrared in these core materials has been studied as a function of time (10−3−104 sec) after pulsed irradiation and cerium concentration (0−1 wt%).
Abstract: High‐numerical‐aperature lead silicate and barium crown glass uncald fibers have been doped with cerium to decrease their radiation sensitivity. The radiation‐induced optical loss in both the visible and near‐infrared in these core materials has been studied as a function of time (10−3–104 sec) after pulsed irradiation and cerium concentration (0–1 wt%). It has been determined that cerium is effective in decreasing the loss at a given time and increasing the decay rate of absorption.
29 citations
TL;DR: In this paper, a defect model was proposed for CaO-doped nonstoichiometric cerium dioxide (Ce1−yCayO2−y−x) in the temperature range 800-1500°C and from oxygen pressures of 10−1-10−21 atm.
27 citations
Patent•
24 Sep 1975
TL;DR: In this article, the reformation process operated in the presence of a catalyst comprising a carrier, platinum, rhodium or osmium, an additional metal consisting of chromium, tungsten, molybdenum, manganese, rhenium, germanium, tin, gallium, indium, thallium, thorium, cerium, samarium, lanthanum, zinc, cadmium, titanium or zirconium, and halogen.
Abstract: Reforming process operated in the presence of a catalyst comprising a carrier, platinum, rhodium or osmium, an additional metal consisting of chromium, tungsten, molybdenum, manganese, rhenium, germanium, tin, gallium, indium, thallium, thorium, cerium, samarium, lanthanum, zinc, cadmium, titanium or zirconium, and halogen.
26 citations
22 citations
TL;DR: The reaction of phenols with cerium(IV) oxide–hydrogen peroxide to give hydroperoxycyclohexadienones is described and the reagent system is shown to be an in situ source of singlet oxygen.
Abstract: The reaction of phenols with cerium(IV) oxide–hydrogen peroxide to give hydroperoxycyclohexadienones is described. In particular 2,6-dihydroxy-3,4-dimethylbenzamide (V) is converted into 3-hydroperoxy-2-hydroxy-3,4-dimethyl-6-oxocyclohexa-1,4-dienecarboxamide (VII). The reagent system is shown to be an in situ source of singlet oxygen.
21 citations
TL;DR: In this paper, thin layer sectioning was used to determine the solute diffusivity of 59 Fe tracers in the light rare-earth metals cerium, praseodymium and neodynium, with values exceeding 10 −5 cm 2 /sec at temperatures above 0.7 T m (T m melting temperature of the solvent metal).
Patent•
25 Apr 1975
TL;DR: An austenitic stainless steel alloy which has extremely good pitting resistance and at the same time has good hot-workability characteristics is described in this article, where a method for making an alloy of the type described above wherein the finishing temperature of hot-rolled strip is maintained around or above 1800° F to reduce edge cracking and preferably is maintained at about 2000° F.
Abstract: An austenitic stainless steel alloy which has extremely good pitting resistance and at the same time has good hot-workability characteristics. The alloy contains, as essential constituents, chromium, nickel, molybdenum, calcium and cerium. In achieving the desirable characteristics of the invention, the molybdenum and chromium levels are important in determining pitting resistance; while recoveries of cerium and calcium in the final alloy are important in determining the hot-workability of the alloy, although cerium is the more important of the two. Sulfur levels are preferably maintained low, on the order of 0.006% or less. Also disclosed is a method for making an alloy of the type described above wherein the finishing temperature of hot-rolled strip is maintained around or above 1800° F to reduce edge cracking and preferably is maintained at about 2000° F.
Patent•
08 Sep 1975TL;DR: Nickel and cobalt base alloy articles are provided coated with a composition consisting essentially of about 20-60% chromium, 6-11% aluminum, 0.01-2.0% of a reactive metal such as yttrium, lanthanum or cerium and the balance nickel as discussed by the authors.
Abstract: Nickel and cobalt base alloy articles are provided coated with a composition consisting essentially of about 20-60% chromium, 6-11% aluminum, 0.01-2.0% of a reactive metal such as yttrium, lanthanum or cerium and the balance nickel.
TL;DR: The results reported in this article indicate that the oxidation of aromatic amines with CAN differs from the behaviour of other metal oxidants as acetates with these substrates, and that the reactivity of some aromatic trinuclear compounds with CAN is different from those of others.
Patent•
27 Jan 1975TL;DR: A new antimony-free yellow pigment was prepared by calcining anatase titanium dioxide with a limited quantitative combination of nickel, tungsten, zinc, lithium, cerium and magnesium compounds as discussed by the authors.
Abstract: A new antimony-free yellow pigment is prepared by calcining anatase titanium dioxide with a limited quantitative combination of nickel, tungsten, zinc, lithium, cerium and magnesium compounds.
Patent•
27 Mar 1975
TL;DR: In this article, Tungsten, phosphorus, vanadium and molybdenum were found to be especially effective for the oxidation of unsaturated aldehydes to form the corresponding unsaturated acid.
Abstract: Catalysts containing tungsten, phosphorus, vanadium and molybdenum have been found to be especially effective for the oxidation of unsaturated aldehydes to form the corresponding unsaturated acid. These catalysts may optionally contain one or more of tin, antimony, arsenic, copper, cerium, boron, chromium, iron, nickel, cobalt, uranium, manganese, strontium, silver, rubidium, rhodium, cadmium, bismuth, indium, zinc and lanthanum.
TL;DR: In this paper, the separation of rhodium and iridium in amounts of 100-1000 μg was achieved with a strongly basic anion-exchange resin, and recoveries of 98% or more were obtained for both metals.
TL;DR: Magnetic susceptibility measurements to temperatures below 5 mK were made on powdered samples of two cerium compounds: a complex of cerium thiocyanate and triphenyl phosphine oxide, and an adiabatic demagnetization experiment was performed on the cerium iodide complex which resulted in an observed minimum magnetic temperature of 1.42 mK as mentioned in this paper.
Abstract: Magnetic susceptibility measurements to temperatures below 5 mK were made on powdered samples of two cerium compounds: a complex of cerium thiocyanate and triphenyl phosphine oxide, and a complex of cerium iodide and antipyrine. In addition, an adiabatic demagnetization experiment was performed on the cerium thiocyanate complex which resulted in an observed minimum magnetic temperature of 1.42 mK. Also discussed is an interesting design feature of the3He−4He dilution refrigerator which makes possible the attainment of temperatures as low as 3.5 mK.
Patent•
17 Jan 1975TL;DR: In this article, it was shown that a particularly useful phosphor conforms substantially to the approximate formula (Ce,Tb) 1 Mg 1 -2 Al 22 O x, where x is the number of atoms of oxygen required to satisfy the valencies of the metals.
Abstract: Phosphors having useful fluorescent emission properties comprise aluminates of magnesium, zinc and/or lithium having an hexagonal or so-called "β-alumina" crystal structure and activated by cerium and terbium. In preferred phosphors the ratio of Mg:Al is from 0.01 to 0.5:1, Ce:Al from 0.001 to 0.1:1 and Tb:Al from 0.005:1 to 0.25:1. Where zinc or lithium wholly or partially replace the magnesium, chemically equivalent amounts may be used. A particularly useful phosphor conforms substantially to the approximate formula (Ce,Tb) 1 Mg 1 -2 Al 22 O x , where x is the number of atoms of oxygen required to satisfy the valencies of the metals. The invention also provides a valuable process for the preparation of such aluminate phosphors, giving a product of fine grain which may not require milling or other severe grinding (which is expensive and tends to harm emission properties) to bring it into the preferred particle size range for lamp manufacture. In this process the source of alumina is aluminium ammonium sulphate (ammonium alum) and this is mixed with oxides of the other constituent metals (or decomposable compounds thereof) and fired at temperatures above 1200° C and preferably at 1450° C and even higher. An increase in brightness may be obtained by a final heating in hydrogen in the region of 1050° C.
Patent•
10 Oct 1975
TL;DR: In this paper, a process for the preparation of an ammonia synthesis catalyst based on fused and reduced iron oxide, with or without traces of a promoter oxide of aluminum, calcium, potassium, magnesium or silicon, was described.
Abstract: The invention relates to a process for the preparation of an ammonia synthesis catalyst based on fused and reduced iron oxide, with or without traces of a promoter oxide of aluminum, calcium, potassium, magnesium or silicon, in which the fused and reduced iron oxide is aftertreated with an aqueous solution of a cerium salt or with an aqueous solution of a mischmetal salt, including a cerium salt.
01 Jun 1975-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the deoxidation thermodynamics of the Fe−Ce−O and Fe−La−O systems were estimated by combining the free energies of solution of cerium and lanthanum in iron, obtained from the respective phase diagrams, with the standard free energies for formation of Cerium and Lanthanum oxides given in the literature.
Abstract: The deoxidation thermodynamics of the Fe−Ce−O and Fe−La−O systems are estimated by combining the free energies of solution of cerium and lanthanum in iron, obtained from the respective phase diagrams, with the standard free energies of formation of cerium and lanthanum oxides given in the literature. Values for the deoxidation constants (w/o Ce)2·(w/o O)3 and (w/o La)2·(w/o O)3 of about 1×10−20 are predicted at steelmaking temperatures. These predicted values are much lower than those obtained experimentally. It is suggested that refractory interactions, and sampling and analytical difficulties, in both laboratory and industrial determinations of these deoxidation constants, lead to erroneously high results.
Patent•
04 Dec 1975
TL;DR: In this paper, the alpha crystal structure of new phosphors which may be activated to luminesce in the red to green portion of the spectrum has been described. Methods of making these phosphors are described.
Abstract: New phosphors which may be activated to luminesce in the red to green portion of the spectrum have an alpha crystal structure isostructural with Ba 2 MnS 3 and the composition Ba.sub.2 Zn.sub.1.sub.-y Cd.sub.y S.sub.3 : A.sub.w.sup.. zZnS wherein A is an activator element selected from the group consisting of manganese, europium, cerium, lead and terbium, y is a numerical value in the range from 0 to 1, z is a numerical value in the range from 0 to 20, and w is a numerical value in the range from 0.00001 to 0.1. Methods of making these phosphors are described.
TL;DR: The emission spectra of the mixed oxides (zirconium and thorium oxides, sesquioxides and lanthanide aluminium or gallium perovskites) correspond mainly to hypersensitive pseudo quadrupolar transitions in the partly filled 4f shell of trivalent lanthanides as discussed by the authors.
Patent•
15 Dec 1975
TL;DR: In this article, maleic anhydride and acrylic acid are produced by the oxidation of 1,3-butadiene, n-butylenes, crotonaldehyde and furan with molecular oxygen in the vapor phase in the presence of a catalytic oxide of antimony, molybdenum, vanadium and lithium, or mixture thereof.
Abstract: Maleic anhydride and acrylic acid are produced by the oxidation of 1,3-butadiene, n-butylenes, crotonaldehyde and furan with molecular oxygen in the vapor phase in the presence of a catalytic oxide of antimony, molybdenum, vanadium and lithium, cerium, or mixture thereof, wherein one element selected from the group consisting of calcium, iron, tungsten, magnesium, aluminum and nickel is optionally added as a reducing agent. The oxidation of 1,3-butadiene in the presence of a catalyst wherein tungsten metal is used as a reducing agent gives especially desirable high yields to maleic anhydride.
TL;DR: In this article, the structure factors of liquid Cerium and Praseodymium have been determined at 1 100 C by neutron diffraction and pair correlation functions, neighbour distances and coordination number were then obtained by Fourier transform.
Abstract: The structure factors of liquid Cerium and Praseodymium have been determined at 1 100 C by neutron diffraction. For theoretical and experimental reasons paramagnetic scattering has been assumed to be identical in both liquid and solid states. The pair correlation functions, neighbour distances and coordination number were then obtained by Fourier transform. The structure factor S(k) exhibits an anomalous behaviour compared with simple metallic ions.