Partial oxidation of methane over bimetallic copper- and nickel-actinide oxides (Th, U)
摘要:
The study of partial oxidation of methane (POM) over bimetallic nickel- or copper-actinide oxides was undertaken. Binary intermetallic compounds of the type AnNi(2) (An = Th, U) and ThCu2 were used as precursors and the products (2NiO UO3, 2NiO ThO2 and 2CuO ThO2) characterized by means of Xray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and temperature-programmed reduction. The catalysts were active and selective for the conversion of methane to H-2 and CO and stable for a period of time of approximate to 18 h on stream. The nickel catalysts were more active and selective than the copper catalyst and, under the same conditions, show a catalytic behaviour comparable to that of a platinum commercial catalyst, 5 wt% Pt/Al2O3 The catalytic activity increases when uranium replaces thorium and the selectivity of this type of materials is clearly different from that of single metal oxides and/or mechanical mixtures. The good catalytic behaviour of the bimetallic copper- and nickel-actinide oxides was attributed to an unusual interaction between copper or nickel oxide and the actinide oxide phase as showed by H-2-TPR, XPS and Raman analysis of the catalysts before and after reaction. (C) 2010 Elsevier B V. All rights reserved.
Mechanical and thermal properties of uranium intermetallic compounds
作者:S. Yamanaka、K. Yamada、T. Tsuzuki、T. Iguchi、M. Katsura、Y. Hoshino、W. Saiki
DOI:10.1016/s0925-8388(98)00152-2
日期:1998.6
coefficients of the intermetalliccompounds were evaluated from high-temperature X-ray diffraction data. The longitudinal and shear sound velocities of the intermetalliccompounds were markedly different, which enabled us to estimate the elastic properties. The intermetalliccompounds were found to have higher bulk moduli than uranium metal. The values of microhardness of the intermetalliccompounds except UFe
Abstract The results of magnetic measurements performed on U(NixAl1−x)2 alloys in the temperature range 4.2 and 800 K are reported. By gradual replacement of aluminum by nickel up to x
摘要 报告了在 4.2 和 800 K 温度范围内对 U(NixAl1-x)2 合金进行磁性测量的结果。通过镍逐渐替代铝,最多 x
We present a comparative study of UNi2 and UNi5 intermetallic compounds and U-Ni thin films prepared by sputter deposition. The aim of this work was to study the electronic structure of the U-Ni alloys. and in particular to investigate to what extent thin films are representative of the corresponding bulk materials. Electronic structure and surface composition was investigated by X-ray and ultra-violet photoelectron spectroscopics respectively. and X-ray induced Auger electron spectroscopy. The composition of thin films. sputter deposited from a UNi5 target. was strongly dependent on deposition conditions (pressure. target voltage). and ranged from U20Ni80 to U14Ni86. Deposition at room temperature resulted in amorphous films. while deposition at a substrate temperature of 473 K lead to the formation of crystalline phases. In all phases, the U 5f electrons are itinerant and remain pinned at the Fermi-level. With increasing U content. the Ni 3d band shifts towards higher binding energies and becomes narrower than in elemental Ni. (C) 2001 Elsevier Science B.V. All rights reserved.