Adsorption of hydrogen on reduced copper chromite

Temperature programmed desorption and volumetric methods in static conditions were used to study hydrogen adsorption on the surface of metallic copper particles produced by the partial reduction of copper chromite CuCr₂O₄ with hydrogen. In the temperature range 300-573 K and in the range of medium surface coverages by hydrogen, the main state of adsorbed hydrogen reveals the heat of adsorption q= 78 kJ/mol and activation energy of adsorption E _a = 69 kJ/mol. In the temperature range 77-300 K, an adsorption state with lower heat and activation energy was found, indicating a non-uniformity of the copper surface within ca. 8% of the total number of surface sites. This revised version was published online in June 2006 with corrections to the Cover Date.     

Catalytic properties of nickel oxide and its solid solutions in magnesium oxide in hydrogen oxidation

Temperature dependence of the reaction rate of H₂ oxidation on nickel oxide and solid solutions of nickel ions in MgO prepared at 573–1373 K, has been studied. The variation of the catalytic properties with temperature is attributed to the presence of nickel ions in different oxidation states simultaneously, i. e. Ni(II) and Ni(III).

---

H₂ MgO, 573–1373 K. — Ni(II) Ni(III).

     

Method to affect catalytic properties of low-temperature transition metal oxides

A method to affect the catalytic properties of low-temperature oxide catalysts by their synthesis through hydroxide compounds of the required composition and structure is suggested.

---

.

     

Physico-chemical studies of the temperature range for the formation of anion-modified oxides

The effect of metal ions on the temperature range for the exstence of anion-modified oxides formed during the formation of Mg and Zn oxides and solid solutions of Cu, Al, Cr and Ni ions in these oxides through thermal decomposition of the respective hydroxo compounds, has been established.

---

- , Mg Zn, Cu, Al, Cr, Ni .

     

Spectral-selective X-ray methods for structure diagnostics of ordered bioorganic nanosystems on a liquid surface

The X-ray standing wave method has been applied to study the formation of protein-lipid film on the water subphase. The influence of different toxic reagents (heavy metals and urea) on protein-lipid interaction in an ordered film of glucose oxidase and behenic acid has been investigated. Analysis of angular dependence of fluorescence yield provided information on molecular arrangement in bioorganic nanosystems on the water surface, where protein and phospholipid molecules were free to move over the water subphase.     

Synthesis and photochemical and magnetic properties of Cr,Mn, Fe,and Co complexes based on the 1-{(1′,3′,3′-trimethylspiro[2<Emphasis Type="Italic">H</Emphasis>-1-benzopyran-2,2′-indolin]-8-yl)methyl}pyridinium cation

Paramagnetic (tris)oxalates with the composition (SP)₃M(C₂O₄)₃·4H₂O (M = Cr (2), Mn (3), Fe (4), and Co (5)) were synthesized for the first time based on the spiropyran salt SP⁺Br⁻ (1) with the SP⁺ cation containing the pyridine ring in the aliphatic chain of the benzopyran moiety, which was also prepared in the present study. According to X-ray diffraction data, the SP⁺ cations in the starting salt 1 are close-packed thus hindering photochromic transformations. The spin for paramagnet 4 is 5/2, which corresponds to the Fe^III atom in the high-spin state, the spin of the system remaining unchanged under UV irradiation. In complex 3, a crossover from ferromagnetic to antiferromagnetic correlations was observed after the replacement of the inorganic cation with the organic spiropyran cation. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1424–1432, July, 2008.     

<Superscript>63</Superscript>Cu and <Superscript>139</Superscript>La NMR and chemical bonding in anion-deficient perovskite LACu<Subscript>0.81</Subscript>Ni<Subscript>0.19</Subscript>O<Subscript>2.5+δ</Subscript>

The ⁶³Cu and ¹³⁹La NMR spectra of the low-(δ = 0.25) and high-temperature (δ = 0) phases of lanthanum cuprate LACu_0.81Ni_0.19O_2.5+δ have been obtained. Quantum chemical calculations of the electronic structure of the high-temperature phase have been performed. It is found that the observed metal-semiconductor phase transition is attended by changes in the degree of atomic ordering and in the character of electronic conductivity over certain types of “copper” centers.     

Thermally induced paramagnetism of spiropyran salts

An increase in the effective magnetic moments and linewidths in ESR spectra caused by the presence of crystallization water molecules in crystals of tris(oxalato)chromium(III) complexes with spiropyran cations Sp⁺ was found. Dehydration (rehydration) of crystals causes a reversible decrease (increase) in thermally induced paramagnetism of Sp⁺. Thermally induced paramagnetism of crystals appears in the compounds synthesized in oxygen atmosphere but is not found in the compounds synthesized under argon atmosphere. The contributions of chromium oxalates and thermally excited spiropyran molecules to the magnetization were separated using ESR spectroscopy. The enthalpies of the biradical states of some types of spiropyran cations in crystals were determined.     

Active state of copper in catalysts for low-temperature methanol synthesis

Copper-containing catalysts have been investigated in low-temperature methanol synthesis. It is shown that the active component of the catalyst is the copper ion and not the metallic copper as is supposed previously.

---

, , , .