Titania supported copper catalysts for methanol synthesis from carbon dioxide

The effect of co-catalyst (ZnO or ZrO₂) has been tested for hydrogenation of CO₂ on CuO/TiO₂ and CuO/Al₂O₃. CuO−ZnO/TiO₂ catalyst showed the highest activity for methanol synthesis. Kinetic parameters were also determined.     

Low-temperature synthesis of niobium oxide nanoparticles from peroxo niobic acid sol

A peroxo niobic acid sol was prepared by peptization of the niobic acid precipitate (Nb2O5.nH2O) with a H2O2 aqueous solution. Crystallized Nb2O5 nanoparticles and niobic acid nanoparticles were obtained by heating the peroxo niobic acid sol. When peroxo niobic acid sol prepared by peptization of the niobic acid precipitate ([NH3]=0.3 mol/l) was heated at 348 K for 1 week, Nb2O5 nanoparticles with a diameter of 4.5 nm and a S(BET) of 275 m2/g were obtained. When peroxo niobic acid sol prepared by peptization of the niobic acid precipitate ([NH3]=1 mol/l) was heated at 348 K for 1 week, niobic acid nanoparticles with a diameter of less than 2 nm were obtained. The pore structure and degree of crystallinity of the nanoparticles prepared by heating the peroxo niobic acid sol greatly depended on the concentration of the ammonia solution used for preparing the niobic acid precipitate.     

Radiolysis of benzyl alcohol in aqueous solution

Radiolysis of 0.05% aqueous solution of benzyl alcohol with 50Co gamma-rays ranging from 1 X 10(4) to 7 X 10(5) rad was investigated, in order to presume the change of it contained in radiopharmaceuticals. For both O2 free and oxygenated solutions, an approximately linear relationship holds between the retaining benzyl alcohol and dose in the range from 1 X 10(5) to 7 X 10(5) rads. The G(-M) values of benzyl alcohol calculated from the relation were 2.34 in the absence and 1.92 in presence of oxygen. In the presence of oxygen, a main product was benzaldehyde and its G value was 0.87. In the absence of oxygen, the main products of the radiolysis were dibenzyl, benzyl phenylcalbinol and hydrobenzoin, which were regarded as the radicao-reaction products of PhCH2 and PhCHOH, and the yield of benzaldehyde was negligible. Irrespective of the presence of oxygen, o- and p-hhdroxylated products of benzyl alcohol were found only in small quantity.     

First Principle Calculation of the Geometrical and Electronic Structure of Impurity-Doped β-FeSi2 Semiconductors

The geometrical and electronic structures of impurity (Cr, Mn, Co, Ni)-doped β-FeSi₂ were investigated using first principles pseudopotential calculations based on generalized gradient approximation (GGA) density function theory. The calculated structural parameters depend strongly on the kinds of dopants and sites. The total energy calculations for substitution of dopants at the Fe_I and the Fe_II sites revealed that Mn prefers the Fe_I site, whereas Cr, Co, and Ni prefer the Fe_II site. The electronic structure is analyzed and discussed in terms of the atomic charges, bond overlap population, and total and partial densities of states (DOS).     

Synthesis of organic‐inorganic hybrid gels by means of thiol‐ene and azide‐alkene reactions

Organic–inorganic hybrid gels have been synthesized from a multi‐vinyl functional cyclic siloxane, 1,3,5,7‐tetravinyltetramethylcyclotetrasiloxane (TVMCTS), or a cubic silsesquioxane, octavinyloctasilasesquioxane (PVOSS), and α,ω‐dithiol compounds, 1,6‐hexanedithiol (HDT), 1,10‐decanedithiol (DDT), using thiol‐ene reaction in toluene. The network structure of the resulting gels, mesh size and mesh size distribution, was quantitatively characterized by means of a scanning microscopic light scattering (SMILS). The gels obtained from TVMCTS‐HDT formed homogeneous network structure with 1.5–1.6 nm mesh. Relaxation peaks derived from large clusters and/or micro gels were detected in the SMILS analysis of the TVMCTS‐DDT, PVOSS‐HDT, and PVOSS‐DDT gels besides those from the small meshes. The organic–inorganic hybrid gels were also synthesized from TVMCTS, PVOSS with α,ω‐diazide compounds, 1,6‐hexanediazide (HDA), 1,10‐decanediazide (DDA), using azide‐alkene reaction in toluene. All the gels obtained with the azide‐alkene reaction formed the homogeneous network structure. Enthalpy relaxation at the glass transition of the dried samples was detected by differential scanning calorimetry to study the network uniformity of the original gels. The gels synthesized by the azide‐alkene reaction showed larger enthalpy than the gels synthesized by the thiol‐ene reaction, indicating homogeneous network structure in the former gels. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2229–2238     

Photo- and electro-luminescent properties of thermotropic liquid crystalline quaterphenyl analogues comprising a 2,2'-bi-1,3,4-thiadiazole unit

Thermotropic liquid crystalline quaterphenyl analogues constituting a central 2,2'-bi-1,3,4- thiadiazole ring, the compounds 5,5'-bis(4-methoxy- and 4-octyloxy-phenyl)-1,3,4-thiadiazole, have been prepared and their photoluminescent (PL) and electroluminescent (EL) properties evaluated. The materials form enantiotropic smectic and nematic phases. The PL spectra showed that they emit blue and green fluorescence in the solid state. The octyloxy compound exhibited an EL spectrum with blue emission and is a candidate for organic EL applications.     

Characterization of homoionic Fe-type montmorillonite: Potential chemical species of iron contaminant

Fe²⁺-montmorillonite with Fe²⁺ ions occupying cation exchange sites is an ideal transformation product in bentonite buffer material. In our previous study on preparation and characterization of Fe²⁺-montmorillonite, the montmorillonite sample that adsorbed Fe²⁺ ions on almost all of the cation exchange sites was prepared using a FeCl₂ solution under an inert gas condition [N. Kozai, Y. Adachi, S. Kawamura, K. Inada, T. Kozaki, S. Sato, H. Ohashi, T. Ohnuki, T. Banba, J. Nucl. Sci. Technol. 38 (2001) 1141]. In view of the unstable nature of iron(II) chemical species, this study attempted to determine the potential contaminant iron chemical species in the sample. Nondestructive elemental analysis revealed that a small amount of chloride ions remained dispersed throughout the clay particles. The chloride ion retention may be due to the adsorption of FeCl⁺ ion pairs in the initial FeCl₂ solution and the subsequent containment of the Cl⁻ ions that are dissociated from the FeCl⁺ ion pairs during excess salt removal treatment. Two explanations are advanced for the second process: the slow release of the remaining Cl⁻ ions from the collapsed interlayer of the montmorillonite, and the transformation of a minor fraction of the remaining FeCl⁺ ion pairs to iron(III) hydroxide chloride complexes having low solubility.     

Sorption of Pu(IV) on biogenic Mn oxide and complexation of Pu(IV) with organic ligands secreted by fungal cells

Journal of Radioanalytical and Nuclear Chemistry - We investigated the sorption of Pu(IV) on biogenic Mn oxide, composed of Mn(IV) oxide and hyphae, produced by Mn(II)-oxidizing fungus. The...     

Potential bacterial alteration of nuclear fuel debris: a preliminary study using simulants in powder and pellet forms

Journal of Radioanalytical and Nuclear Chemistry - Remnant nuclear fuel debris in the damaged nuclear reactors at the Fukushima Daiichi Nuclear Power Plant (FDNPP) has contacted the groundwater...