WILSON ROBERTO DOS SANTOS

WILSON ROBERTO DOS SANTOS

Página do item completo

Resultados de Busca

Agora exibindo 1 - 7 de 7

Use of dopants for thoria sintering temperature reduction-characterization of THO2
2016 - TAKIISHI, HIDETOSHI; GENOVA, LUIS A.; CAVALHEIRA, ELTON D.; COTRIM, MARYCEL B.; SANTOS, WILSON; LAINETTI, PAULO E.O.
Thorium is nearly three times more abundant than uranium in the Earth’s crust. Some papers evaluate the thorium resources in Brazil over 1,200,000 metric t. These figures mean that the country is probably the biggest thorium resource in the world, with only part of the territory prospected. Nevertheless, Brazil has not a research program for use of thorium in nuclear reactors, even having dedicated special attention to the subject in the beginning of its nuclear activities, in the fifties and sixties. From 1985 until 2003 IPEN operated a pilot plant for thorium nitrate production and purification, used by Brazilian industry for production of gas mantles. This facility produced over 170 metric t of thorium nitrate. Despite the non-nuclear application, the pilot plant was unique in the southern hemisphere. On the other hand, Brazil has the biggest world niobium resources. The Brazilian thorium and niobium resources added to the predictable future importance of alternative fissile materials have motivated this research, since uranium is a finite resource if used in the present thermal nuclear reactors. Besides this, thorium oxide is an important nuclear reactor material. It is a refractory oxide and its ceramic fabrication process involves a very high temperature sintering treatment considering that thoria melting point is very high (3,650 K). Cations of elements of the group VB (V, Nb and Ta) have a known effect in the reduction of thoria sintering temperature. IPEN has initiated an investigation about the use of niobium as a dopant for thoria sintering temperature reduction. The thoria used in the research was produced in the IPEN’s pilot plant and different amounts of niobium oxide (Nb2O5) will be added to thoria by different routes. The powders will be compressed and the compacted pellets will be sintered at different temperatures. The influence of the different parameters in the density of sintered pellets is being investigated. This paper presents the chemical and physical characterization for the thoria used in the investigation.
Preparacao de microesferas de alumina. Aplicacao como trocador inorganico
1981 - SANTOS, W.R.; ABRAO, A.
Use of dopants for thoria sintering temperature reduction - characterization of ThOsub(2)
2015 - TAKIISHI, HIDETOSHI; GENOVA, LUIS A.; CAVALHEIRA, ELTON D.; COTRIM, MARYCEL B.; SANTOS, WILSON R.; LAINETTI, PAULO E.O.
Synthesis and characterization of Ni-Cu/ZrO2 and Co-Cu/ZrO2 catalysts used for ethanol steam reforming
2005 - BERGAMASCHI, V.S.; CARVALHO, F.M.S.; SANTOS, W.R.; RODRIGUES, C.
Zirconia has received much attention as catalysts for its high surface area and acid-base property. The textural and acid-base properties of ZrO2 depend on both, the synthesis procedure and the calcinations temperature. The aim of the present study is the preparation and characterization of nickel/cupper/zirconia and cobalt/cupper/zirconia microspheres using hydrolysis process. This process is based on homogeneous hydrolysis of droplets of a concentrated ZrO2(NO3)2-urea solution after adding hexamethyletetramine. Gelation was conduced successfully and the gel spheres were dried at 80 ºC. The dried gel spheres were thermally treated at 550 ºC. Characterization of the samples was performed using X-ray diffraction (XRD), BET nitrogen adsorption, scanning electron microscopy (SEM), thermogravimetric (TGA) and UV-Vis spectroscopy. The performance of the microspheres was investigated as catalysts in steam reforming of ethanol. Theses catalysts exhibit a good selectivity for hydrogen.
Obtencao de UOsub(3) por desnitracao do nitrato de uranilo, em leito fluidizado
1990 - SANTOS, W.R.; COSTA, P.A.
Obtencao de oxido de cerio com alta superficie especifica
1990 - GENOVA, L.A.; BRESSIANI, A.H.A.; BRESSIANI, J.C.; MARTINELLI, J.R.; MUCCILLO, E.N.S.; MUCCILLO, R.; SANTOS, W.R.; ASSIS, G.; LAMEIRAS, F.S.
Synthesis and characterization of Ni-Cu/ZrOsub(2) and Co-Cu/ZrOsub(2) catalysis used for ethanol steam reforming
2006 - BERGAMASCHI, V.S.; CARVALHO, F.M.S.; SANTOS, W.R.; RODRIGUES, C.
Zirconia has received much attention as catalysts for its high surface area and acid-base property. The textural and acid-base properties of ZrO2 depend on both, the synthesis procedure and the calcinations temperature. The aim of the present study is the preparation and characterization of nickel/cupper/zirconia and cobalt/cupper/zirconia microspheres using hydrolysis process. This process is based on homogeneous hydrolysis of droplets of a concentrated ZrO2(NO3)2-urea solution after adding hexamethyletetramine. Gelation was conduced successfully and the gel spheres were dried at 80 °C. The dried gel spheres were thermally treated at 550 °C. Characterization of the samples was performed using X-ray diffraction (XRD), BET nitrogen adsorption, scanning electron microscopy (SEM), thermogravimetric (TGA) and UV-Vis spectroscopy. The performance of the microspheres was investigated as catalysts in steam reforming of ethanol. Theses catalysts exhibit a good selectivity for hydrogen.