Niobium Oxides
Mostrando 1-12 de 15 artigos, teses e dissertações.
-
1. Metal-Supported Niobium Catalysts Investigation for Conversion of Bio-Renewable Glycerol to Organic Compounds
The glycerol oxidative dehydration to organic compounds, especially acrolein and acrylic acid, was studied over vanadium, molybdenum, and cobalt oxides supported on niobium oxide and niobium phosphate catalysts. At 300 °C, the glycerol conversion was 100% over all catalysts tested, and acrolein was the main product observed, without significant deactivation
Journal of the Brazilian Chemical Society. Publicado em: 2022
-
2. Study of the Nb2O5 Insertion in ZnO to Dye-sensitized Solar Cells
Dye-sensitized solar cells (DSSC) have received much attention as an alternative to silicon-based solar cells, due to various advantages. Zinc oxide (ZnO) is an n-type semiconductor employed as photoanode on DSSC. The decrease of charge recombination is an efficient strategy capable of improving the photovoltaic performance of the device. In this perspective
Mat. Res.. Publicado em: 01/07/2019
-
3. Methyl Esters Production by Heterogeneous Catalyst Mixtures of CaO/Nb2O5 with Simulation of Analysis of Environmental Impacts
The conventional biodiesel process, although it reaches high conversion yields and productivity, faces problems related to the use of homogeneous catalysts. This work aims to study mixtures of calcium oxide (CaO) and niobium oxide (Nb2O5) as the heterogeneous catalyst. It was used a full 23 factorial design with four central points to analyze how the mass pe
J. Braz. Chem. Soc.. Publicado em: 2019-03
-
4. A Model for the Formation of Niobium Structures by anodization
The fluoride use for anodizing electrolytes has been primarily responsible for the formation of nanoporous oxides at valve metals, except aluminum, since it causes a dissolution process. This study presents the formation of an oxide model according to the following anodizing parameters: 100 V, 12.73 mA/cm2, room temperature and the niobium samples anodized i
Mat. Res.. Publicado em: 25/05/2017
-
5. Platinum and nioubium based catalysts for the anode of polymer electrolyte membrane fuel cells fed with low molecular weight alcohols / Catalisadores a base de platina e nióbio para o ânodo da célula a combustível de membrana trocadora de prótons alimentada com alcoóis de baixa massa molecular
In this work, the methanol and ethanol electrochemical oxidation reactions are studied on platinum (Pt) and niobium (Nb) catalysts supported on high surface area carbon. The selected materials were PtNb/C, Pt-Nb2O5(amorphous) /C e Pt-Nb2O5(crystalline) /C, using as reference for comparison purposes the commercial catalyst 20% Pt-C E-TEK. The catalysts were p
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 25/01/2012
-
6. Efeito de metais de transição sobre a polarização espontânea na estrutura cristalina de nanopós da família tungstênio bronze
This work aimed the study of the effect of transition metals (Ni, Fe, Co) on the spontaneous polarization of the ferroelectric oxides of tetragonal tungsten bronze (TTB)-type structure of potassium strontium niobate (KSr2Nb5O15) and of the KSr2(FeNb4)O15-d, KSr2(NiNb4)O15-d and KSr2(CoNb4)O15-d solid solutions. All systems investigated were prepared by mecha
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 28/02/2011
-
7. Petrologia e metalogenia do depósito primário de nióbio do complexo carbonatítico-foscorítico de Catalão I, GO
The Catalão I carbonatite-phoscorite complex is part of the Alto Paranaíba Igneous Province (APIP) and consists of a multi-intrusion body zoned from bebedourite-(piroxenite)-series rocks in the border to carbonatite- and phoscorite-series rocks in the core. The phoscorite-series rocks consist of apatite, magnetite and a Mg-silicate (phlogopite or olivine)
Publicado em: 2009
-
8. Melhoria da Lingotabilidade do Aço Inoxidável Ferrítico AISI 409 na ArcelorMittal Inox Brasil
Stainless steels are known for their beauty and corrosion resistance. Ferritic stainless steels, without nickel, are responsible for the increase the consumption of stainless steels in the world, due to the economic advantage as compared to austenitic stainless steels. In the automobile industry, more specific in the cars exhaust system, the use of ferritic
Publicado em: 2009
-
9. Efeitos de aditivos na sinterização do combustivel nuclear UO2.Gd2O3 / Effects of additives on the sintering of UO2.Gd2O3
The addition of 0.5wt% TiO2, Nb2O5, SiO2, Fe2O3 and Al(OH)3 in the UO2·7%Gd2O3 nuclear fuel and the effect on its sintering kinetics under a 99.999% H2 atmosphere were investigated by stepwise isothermal dilatometry. This fuel, used as burnable poison in nuclear power plants, presents a diffusion barrier around 1573 K that impairs densification. The aid of
Publicado em: 2009
-
10. Sinterização de aço inoxidável reforçado com partículas nanométricas dispersas de carbeto de nióbio - NbC
Metal powder sintering appears to be promising option to achieve new physical and mechanical properties combining raw material with new processing improvements. It interest over many years and continue to gain wide industrial application. Stainless steel is a widely accepted material because high corrosion resistance. However stainless steels have poor sinte
Publicado em: 2007
-
11. Obtenção de pós de tântalo metálico a partir da redução aluminotérmica com ignição a plasma
Metallic tantalum has a high commercial value due to intrinsic properties like excellent ductility, corrosion resistance, high melt and boiling points and good electrical and thermal conductivities. Nowadays, it is mostly used in the manufacture of capacitors, due to excellent dielectric properties of its oxides. In the nature, tantalum occurs in the form of
Publicado em: 2007
-
12. A comparative study between alumina-tetragonal zirconia composites and alumina - niobia ceramics for structural applications / Estudo comparativo de compósitos alumina-zircônia tetragonal e de cerâmicas de alumina aditivada com nióbia para aplicações estruturais
O objetivo deste trabalho é estudar os efeitos da adição de partículas de Zircônia na estrutura de uma composição de Alumina Nióbia em estudo pelo Projeto Marimba, assim como analisar a respectiva influência nas propriedades mecânicas do material para que possa ser utilizado em aplicações estruturais. Foram utilizados quatro tipos de Zircônia: Z
Publicado em: 2007