Application of Pt/Al2O3 catalysts produced by sol-gel process to uranyl ion reduction

Various kinds of active alumina supports were obtained by the Institute of Nuclear Chemistry and Technology (INCT) sol-gel process in the following steps: (1) preparation of alumina sols by extraction of nitrates with Primene JMT from aluminium nitrate solution; (2) gelation to spherical particles (with diameter 100 m2/g at 500°C. The powders were then impregnated with chloroplatinic acid and recalcined at 500°C. Catalysts were also prepared by direct gelation of alumina sol containing hydroplatinic acid followed by steps (3) and (4). Pt/Al2O3 catalysts were used for the reduction of 1M UO2(NO3)2 - 0.5M HCOOH solution with hydrogen at atmospheric pressure. The course of the reduction was controlled analytically and by measuring the U(VI)/U(IV) redox potential. It was concluded that the catalysts obtained by impregnation of the supports prepared from nitrate stabilized gels exhibit the best activity and stability

Preparation of lithium titanate by sol-gel method

Medium sized spherical particles of Li2TiO3 (with diameters below 100 mi m) can be prepared from peroxy lithium titanate solution (stabilized with citric acid) by a modified INCT variant of the sol-gel process. The process consists of the following main steps: (I) formation of aqueous phase emulsion in 2-ethylhexanol-1 containing the surfactants 1v/o SPAN-80 and 1v/o Ethomen S-15 (EH); (II) gelation of emulsion drops by extraction of water with partially dehydrated EH; (III) filtration and washing with carbon tetrachloride or acetone; (IV) non-destructive thermal treatment. The tritium release from sol-gel process preparation of Li2TiO3 micro-spheres was found very close to that observed for other traditional material however, the new process is more efficient than other processes because of the morphology of the sintered specimens

Superconducting and Microstructural Properties of (Mg+2B)+MgB2\text{}_{2}/Cu Wires Obtained by High Gas Pressure Technology

In order to improve the overall critical current characteristics of Cu sheathed in situ MgB$\text{}_{2}$ wires a special architecture of the wire, and processing parameters were used. The study presents the influence of the ex situ MgB$\text{}_{2}$ chemical barrier between ex situ core and Cu, suppressing the reaction of Cu with Mg. Wires, doped with 10 at.% SiC of 18 nm average grain size, were fabricated from MgH$\text{}_{2}$ and B or from Mg and B powders, using the powder-in-tube method. The methods of rotary swaging or drawing were used as the alternating wire-forming processes. The samples were annealed under high Ar gas pressure (hot isostatic pressing) at 750ºC and 1.0 GPa for 15 and 30 min. A significant difference in Cu distribution across the wires for a long and short time of sintering was observed. The formation of microstructure in the powder-in-tube process and the relationship between the microstructure and critical current density J$\text{}_{c}$ values, are discussed in this paper