Tungsten Catalysts
Mostrando 1-9 de 9 artigos, teses e dissertações.
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1. Activity and Stability of Dispersed Multi Metallic Pt-based Catalysts for CO Tolerance in Proton Exchange Membrane Fuel Cell Anodes
ABSTRACT Studies aiming at improving the activity and stability of dispersed W and Mo containing Pt catalysts for the CO tolerance in proton exchange membrane fuel cell (PEMFC) anodes are revised for the following catalyst systems: (1) a carbon supported PtMo electrocatalyst submitted to heat treatments; (2) Pt and PtMo nanoparticles deposited on carbon-supp
An. Acad. Bras. Ciênc.. Publicado em: 16/04/2018
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2. NANOPARTICLES OF TUNGSTEN AS LOW-COST MONOMETALLIC CATALYST FOR SELECTIVE HYDROGENATION OF 3-HEXYNE
Low-cost tungsten monometallic catalysts containing variable amounts of metal (4.5, 7.1 and 8.5%W) were prepared by impregnating alumina with ammonium metatungstate as an inexpensive precursor. The catalysts were characterized using ICP, XPS, XRD, TPR and hydrogen chemisorption. These techniques revealed mainly WO3-Al2O3 (W6+) species on the surface. The eff
Quím. Nova. Publicado em: 2016-01
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3. Processing of spent NiW/Al2O3 catalysts
Spent oxidized (500 ºC, 5 h) commercial NiW/Al2O3 catalysts were processed using two different routes: a) fusion with NaOH (650 ºC, 1 h), the roasted mass was leached in water; b) leaching with HCl or H2SO4 (70 ºC, 1-3 h). HCl was the best leachant. In both routes, soluble tungsten was extracted at pH 1 with Alamine 336 (10 vol.% in kerosene) and stripped
Quím. Nova. Publicado em: 2013
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4. Análise por componentes principais de espectros nexafs na especiação do molibdênio em catalisadores de hidrotratamento
Bulk and supported molybdenum based catalysts, modified by nickel, phosphorous or tungsten were studied by NEXAFS spectroscopy at the Mo L III and L II edges. The techniques of principal component analysis (PCA) together with a linear combination analysis (LCA) allowed the detection and quantification of molybdenum atoms in two different coordination states
Química Nova. Publicado em: 2010
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5. Reactivity of tungsten-aryloxides with hydrosilane cocatalysts in olefin metathesis
As reatividades dos sistemas [WCl4(OAr)2] (OAr = O-2,6-C3H3Cl2, O-2,6-C6H3F2 e OC 6H3Me2), juntamente com os compostos de silício Ph2SiH2 e polimetilidrosiloxano (PMHS), foram estudadas em reações de metátese. As olefinas usadas foram 10-undecenoato de metila e 1- hexeno. Os resultados mostraram que os sistemas [WCl4(OAr)2]-composto de silício são ativ
Publicado em: 2010
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6. Pd-W and Pd-Mo catalysts for NO decomposition and NO/CO reduction reactions
Catalisadores Pd/γ-Al2O3 com dois tamanhos de partículas metálicas foram preparados a partir de [Pd(acac)2]. Subsequentemente, a reação fotoquímica de [M(CO)6] (M = Mo ou W) na presença de Pd/γ-Al2O3 foi usada para preparar catalisadores bimetálicos Pd-M/γ-Al2O3. Os espectros DRIFTS-IVTF das superfícies destes catalisadores antes da decomposição
Publicado em: 2010
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7. Desenvolvimento de catalisadores bifuncionais de óxido de zircônio modificado por óxidos de tungstênio e molibdênio contendo platina para a reação de isomerização de n-parafinas / Development of bifunctional catalysts on zircon oxide modify by tungsten and molybdenum oxides contain platinum for nparaffin isomerization
Bifunctional catalysts based on zircon oxide modified by tungsten (W = 10, 15 and 20 %) and by molybdenum oxide (Mo= 10, 15 e 20 %) containg platinum (Pt = 1%) were prepared by the polymeric precursor method. For comparison, catalysts the tungsten base was also prepared by the impregnation method. After calcinations at 600, 700 and 800 C, the catalysts were
Publicado em: 2007
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8. Propane oxidation on Pt-WO3/gamma -AL2O3 catalytic systems
The oxidation of propane on was studied with Pt-xWO3/Al2O3 catalysts was studied ,by varying the concentration of tungsten sublayer. Thermal analysis and XRD in situ showed that the enrichment of tungsten at the surface is associated with the formation of HxWO3 bronze. FTIR results with C3H8 and O2 indicated that the catalyst surface properties and the inter
Brazilian Journal of Chemical Engineering. Publicado em: 2003-03
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9. DECOMPOSITION OF HYDRAZINE BY TUNGSTEN OXYCARBIDES: THE INFLUENCE OF MACROPOROSITY AND MECHANICAL STRENGTH ON A 2 N MICROTHRUSTER ENGINE
The aim of this work was to prepare tungsten oxycarbides by Temperature Programmed Reaction (TPR), starting with previously molded macroporous tungsten oxide (WO3). The tungsten oxycarbides were prepared by one of two different methods: direct carburization with CH4/H2 to obtain WC or preliminary formation of nitrides with NH3 to obtain W2N, followed by carb
Brazilian Journal of Chemical Engineering. Publicado em: 2001-12