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Production of hydrogen via steam reforming of biofuels on Ni/CeO(2)-Al(2)O(3) catalysts promoted by noble metals

PROFETI, Luciene P. R.; TICIANELLI, Edson A.; ASSAF, Elisabete M.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
48.2029%
The catalytic activity of Ni/CeO(2)-Al(2)O(3) catalysts modified with noble metals (Pt, Ir, Pd and Ru) was investigated for the steam reform of ethanol and glycerol. The catalysts were characterized by the following techniques: Energy-dispersive X-ray, BET, X-ray diffraction, temperature-programmed reduction, UV-vis diffuse reflectance spectroscopy and X-ray absorption near edge structure (XANES). The results showed that the formation of inactive nickel aluminate was prevented by the presence of CeO(2) dispersed on alumina. The promoting effect of noble metals included a decrease in the reduction temperatures of NiO species interacting with the support, due to the hydrogen spillover effect. It was seen that the addition of noble metal stabilized the Ni sites in the reduced state along the reforming reaction, increasing the ethanol and glycerol conversions and decreasing the coke formation. The higher catalytic performance for the ethanol steam reforming at 600 degrees C and glycerol steam reforming was obtained for the NiPd and NiPt catalysts, respectively, which presented an effluent gaseous mixture with the highest H(2) yield with reasonably low amounts of CO. (c) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP; CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ethanol steam reforming for production of hydrogen on magnesium aluminate-supported cobalt catalysts promoted by noble metals

PROFETI, Luciene P. R.; TICIANELLI, Edson A.; ASSAF, Elisabete M.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
58.11722%
The performance of noble metal (Pt, Ru, Ir)-promoted Co/MgAl(2)O(4) catalysts for the steam reforming of ethanol was investigated. The catalysts were characterized by energy-dispersive X-ray spectroscopy, Xray diffraction, UV-vis diffuse reflectance spectroscopy, temperature-programmed reduction, temperature-programmed oxidation and X-ray absorption near edge structure (XANES). The results showed that the formation of inactive cobalt aluminate was suppressed by the presence of a MgAl(2)O(4) spinel phase. The effects of the noble metals included a marked lowering of the reduction temperatures of the cobalt surface species interacting with the support. It was seen that the addition of noble metal stabilized the Co sites in the reduced state throughout the reaction. Catalytic performance was enhanced in the promoted catalysts, particularly CoRu/MgAl(2)O(4), which showed the highest selectivity for H(2) production. (C) 2009 Elsevier B.V. All rights reserved.; FAPESP; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Laboratorio Nacional de Luz Sincrotron[LNLS/D06A-DXAS]; Laboratorio Nacional de Luz Sincrotron

Hydrogen production by steam reforming of ethanol over Ni-based catalysts promoted with noble metals

PROFETI, Luciene P. R.; DIAS, Joelmir A. C.; ASSAF, Jose M.; ASSAF, Elisabete M.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
48.29072%
The catalytic activity of Ni/La(2)O(3)-Al(2)O(3) Catalysts modified with noble metals(Pt and Pd) was investigated in the steam reforming of ethanol. The catalysts were characterized by ICP, S(BFT), X-ray diffraction, temperature-programmed reduction, UV-vis diffuse reflectance spectroscopy and X-ray absorption fine structure (XANES). The results showed that the formation of inactive nickel aluminate was prevented by the presence of La(2)O(3) dispersed on the alumina. The promoting effect of noble metals included a marked decrease in the reduction temperatures of NiO species interacting with the support. due to the hydrogen spillover effect, facilitating greatly the reduction of the promoted catalysts. it was seen that the addition of noble metal stabilized the Ni sites in the reduced state throughout the reaction, increasing ethanol conversion and decreasing coke formation, irrespective of the nature or loading of the noble metal. (C) 2009 Elsevier B.V. All rights reserved.; FAPESP; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Co/Al2O3 catalysts promoted with noble metals for production of hydrogen by methane steam reforming

PROFETI, Luciene P. R.; TICIANELLI, Edson A.; ASSAF, Elisabete M.
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
48.2029%
The effect of noble metal addition on the catalytic properties of Co/Al2O3 was evaluated for the steam reforming of methane. Co/Al2O3 catalysts were prepared with addition of different noble metals (Pt, Pd, Ru and Ir 0.3 wt.%) by a wetness impregnation method and characterized by UV-vis spectroscopy, temperature programmed reduction (TPR) and temperature programmed oxidation (TPO) of the reduced catalysts. The UV-vis spectra of the samples indicate that, most likely, large amounts of the supported cobalt form Co species in which cobalt is in octahedral and tetrahedral symmetries. No peaks assigned to cobalt species from aluminate were found for the promoted and unpromoted cobalt catalysts. TPO analyses showed that the addition of the noble metals on the Co/Al2O3 catalyst leads to a more stable metallic state and less susceptible to the deactivation process during the reforming reaction. The Co/Al2O3 promoted with Pt showed higher stability and selectivity for H(2)production during the methane steam reforming. (C) 2007 Elsevier Ltd. All rights reserved.

Production of hydrogen by ethanol steam reforming on Co/Al2O3 catalysts: Effect of addition of small quantities of noble metals

PROFETI, Luciene P. R.; TICIANELLI, Edson A.; ASSAF, Elisabete M.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
48.07326%
The catalytic performance of Co/Al2O3 catalysts promoted with small amounts noble metals (Pt, Pd, Ru, Ir) for steam reforming of ethanol (SRE) has been investigated. The catalysts were characterized by the energy dispersive X-ray, X-ray diffraction, BET surface area, X-ray absorption fine structure and temperature reduction programmed techniques. The results showed that the promoting effect of noble metals included a marked decrease of the reduction temperatures of both Co3O4 and cobalt surface species interacting with the support due to the hydrogen spillover effect, leading to a significant increase of the reducibilities of the promoted catalysts. The better catalytic performance for the ethanol steam reforming at 400 degrees C was obtained for the CoRu/Al2O3 catalyst, which presented an effluent gaseous mixture with the highest H, selectivity and the reasonable low CO formation. (C) 2007 Published by Elsevier B.V.

Atividade fotocatalítica de filmes nanoestruturados de dióxido de titânio incorporados com nanopartículas de metais nobres; Noble metals nanoparticles on titanium dioxide nanostructured films and the influence of their photocatalytic activity

Nakamura, Liana Key Okada
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 30/10/2012 PT
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47.6891%
Atualmente, a nanociência e nanotecnologia são consideradas como um campo emergente onde, continuamente, as barreiras entre as disciplinas são rompidas. Seu principal foco de estudo consiste em buscar o controle estrutural ao nível molecular, arranjando os átomos de modo a se conseguir um entendimento e controle das propriedades fundamentais da matéria. Neste estudo foram propostas modificações moleculares e, consequentemente, na morfologia, propriedades ópticas e cristalinas em filmes finos de TiO2 com o objetivo de aumentar sua eficiência fotônica. Os filmes finos de TiO2 foram preparados pelo processo sol-gel avaliando a influência de diferentes ácidos e agente direcionador para a obtenção dos arranjos nanoestruturados. A seguir, os filmes que apresentaram maior eficiência fotônica foram incorporados com nanopartículas metálicas (Au, Ag, Pd e Pt) com objetivo de minimizar os processos de recombinação eletrônica do par lacuna/elétron. Das diversas rotas estudadas, os filmes finos de TiO2 preparados com ácido acético obtiveram maior eficiência fotônica devido à pouca aglomeração dos grãos de titânia, o que pode ter favorecido uma maior exposição dos sítios fotocatalíticos. A presença do agente direcionador na formulação teve pouco efeito na eficiência fotônica...

Efeitos de promotores no desempenho catalítico do cobalto suportado em nanofibras de carbono na síntese de Fischer-Tropsch; Promoter effects on catalytic performance of cobalt supported on carbon nanofibers in the Fischer-Tropsch synthesis

Carvalho, André
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 06/10/2014 PT
Relevância na Pesquisa
47.6891%
A síntese de Fischer-Tropsch é um processo de conversão do gás de síntese (CO + H2) em hidrocarbonetos de cadeias longas. Os catalisadores clássicos para a hidrogenação do CO são, principalmente, o Fe e o Co suportados em diferentes óxidos. O desempenho catalítico do catalisador é influenciado pelo tamanho, dispersão e grau de redução das partículas metálicas. Estudos recentes mostram uma promissora aplicação de materiais à base de nanofibras de carbono na catálise heterogênea. Estes materiais apresentam algumas vantagens em relação aos suportes catalíticos tradicionais, tais como: uma baixa interação metal-suporte, elevada área superficial, ausência de poros fechados, alta condutividade térmica, elevada inércia química e hidrofobicidade. Neste trabalho foram fabricados suportes catalíticos macroscópicos à base de nanofibras de carbono, empregando o método de vapor deposição, a partir da decomposição do etano. Os catalisadores foram preparados pela impregnação incipiente do Co e de promotores na superfície do suporte. Foram empregados os metais nobres, Ir, Pt e Ru, como promotores catalíticos, com o objetivo de incrementar a redutibilidade e a atividade do catalisador. Todos os catalisadores foram caracterizados por Quimissorção de CO...

Diagnose de microbiólitos metálicos em espécies vegetais endêmicas em solos de rochas ultramáficas por microscopia eletrônica de varredura

Lima e Cunha, Maria do Carmo; Mariath, Jorge Ernesto de Araujo; Menegotto, Egydio; Formoso, Milton Luiz Laquintinie
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
Relevância na Pesquisa
48.07326%
The aim of this paper is to investigate by SEM the presence of crystalline forms of noble metals in dehydrated tissues of Scutia buxifolia (Rhamnaceae), Scoparia montevidensis (Scrophulariaceae) and Adiantopsis cf. chlorophylla (Pteridaceae), a endemic vegetation on ultramafic soils from Pedras Pretas, São Sepé, southermost Brazil. Chemical composition of rocks, soils and ash plants were also determined by ICP-MS. The rocks and soils from Pedras Pretas show the expected geochemical pattern of ultramafic ones. Despite the low concentrations of some trace elements and noble metals in ash plants, the BSE images obtained by electron microprobe reveal the presence of semicrystals of Au, Pt, and Ag, besides Ni, Cr, Fe and Ca in xilem parenchyma cells from the species concerned. These preliminary data show the necessity of combination of mineralogical with biogeochemical and physiological investigations in order to demonstrate the importance of these plants in forming biominerals. Moreover, studies about metallic concentrations in plant tissues can contribute to the comprehension of detoxication mechanisms of plants that can be applied for phytoremediation purposes.

Lattice dynamics of noble metals on effective three-body interaction

Coelho, A. A.; Shukla, M. M.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 615-623
ENG
Relevância na Pesquisa
48.252354%
Quite recently we modified the original model of Sarkar et al. for cubic metals in extending the ion-ion interaction, ion-electron interaction and the introduction of crystal equilibrium condition. We applied our scheme to alkali metals. We studied here the lattice dynamics of noble metals on our approach by calculating phonon dispersion relations along the three principal symmetry directions, [ξ00], [ξξ00] and [ξξξ] and the (θ-T) curves of three noble metals: copper, silver and gold. We obtained reasonable agreement with the experimental findings.

Mono- and bimetallic Rh and Pt NSR-catalysts prepared by controlled deposition of noble metals on support or storage component

Büchel, Robert; Pratsinis, Sotiris E.; Baiker, Alfons
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 22/02/2012 EN
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48.07326%
Mono- and bimetallic Rh and Pt based NOx storage-reduction (NSR) catalysts, where the noble metals were deposited on the Al2O3 support or BaCO3 storage component, have been prepared using a twin flame spray pyrolysis setup. The catalysts were characterized by nitrogen adsorption, CO chemisorption combined with diffuse reflectance infrared Fourier transform spectroscopy, X-ray diffraction, and scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy. The NSR performance of the catalysts was investigated by fuel lean/rich cycling in the absence and presence of SO2 (25 ppm) as well as after H2 desulfation at 750 °C. The performance increased when Rh was located on BaCO3 enabling good catalyst regeneration during the fuel rich phase. Best performance was observed for bimetallic catalysts where the noble metals were separated, with Pt on Al2O3 and Rh on BaCO3. The Rh-containing catalysts generally showed much higher tolerance to SO2 during fuel rich conditions and lost only little activity during thermal aging at 750 °C.

HYDROGEN DIFFUSIVITY IN NOBLE METALS AT LOW TEMPERATURES (ELECTROCHEMICAL)

ISHIKAWA, TOMAZ TOSHIMI
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
47.8626%
An electrochemical technique has been used to measure the diffusivity of hydrogen in high purity noble metals (Ag, Au, Cu, Pd and Pt) in the well-annealed state at low temperatures (283-323K). The data obtained have been considered in conjunction with those for as-quenched and aged Au samples in order to draw conclusions concerning the interactions between dissolved H atoms and lattice vacancies. It has been concluded, at least, in Pd, Cu and Au, that the H-vacancy interaction energy is too low to render diffusion anomalies observable at high temperatures. This is in accord with theoretical calculations based on the effective medium technique. The resulting diffusivities for quenched and aged Au are consistent with a simple statistical model in which a fraction of the H atoms saturate traps formed by quenching in vacancies, but the mobility is primarily determined by the excess of nontrapped H atoms diffusing through "normal" sites in FCC metals.

Coupling Noble Metals and Carbon Supports in the Development of Combustion Catalysts for the Abatement of BTX Compounds in Air Streams

Morales-Torres, Sergio; Carrasco Mar??n, Francisco; P??rez-Cadenas, Agust??n F.; Maldonado-H??dar, Francisco Jos??
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
68.07326%
The catalytic combustion of volatile organic compounds (VOCs) is one of the most important techniques to remove these pollutants from the air stream, but it should be carried out at the lowest possible temperature, saving energy and avoiding the simultaneous formation of nitrogen oxides (NOx). Under these experimental conditions, the chemisorption of water generated from VOCs combustion may inhibit hydrophilic catalysts. Nowadays, a wide variety of carbon materials is available to be used in catalysis. The behavior of these hydrophobic materials in the development of highly active and selective combustion catalysts is analyzed in this manuscript. The support characteristics (porosity, hydrophobicity, structure, surface chemistry, etc.) and the active phase nature (noble metals: Pt, Pd) and dispersion were analyzed by several techniques and the results correlated with the dual adsorptive and/or catalytic performance of the corresponding catalysts. The coupling of highly active phases and carbon materials (activated carbons, honeycomb coated monoliths, carbon aerogels, etc.) with tuneable physicochemical properties leads to the complete abatement of benzene, toluene and xylenes (BTX) from dilute air streams, being selectively oxidized to CO2 at low temperatures.

Plasmonic excitations in noble metals: The case of Ag

Cazalilla, M. A.; Dolado, J. S.; Rubio, A.; Echenique, P. M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/07/1999
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The delicate interplay between plasmonic excitations and interband transitions in noble metals is described by means of {\it ab initio} calculations and a simple model in which the conduction electron plasmon is coupled to the continuum of electron-hole pairs. Band structure effects, specially the energy at which the excitation of the $d$-like bands takes place, determine the existence of a subthreshold plasmonic mode, which manifests itself in Ag as a sharp resonance at 3.8 eV. However, such a resonance is not observed in the other noble metals. Here, this different behavior is also analyzed and an explanation is provided.; Comment: 9 pages, 8 figures

Broken-Bond Rule for the Surface Energies of Noble Metals

Galanakis, I.; Bihlmayer, G.; Bellini, V.; Papanikolaou, N.; Zeller, R.; Bluegel, S.; Dederichs, P. H.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.8626%
Using two different full-potential ab-initio techniques we introduce a simple, universal rule based on the number of broken first-neighbor bonds to determine the surface energies of the three noble metals Cu, Ag and Au. When a bond is broken, the rearrangement of the electronic charge for these metals does not lead to a change of the remaining bonds. Thus the energy needed to break a bond is independent of the surface orientation. This novel finding can lead to the development of simple models to describe the energetics of a surface like step and kink formation, crystal growth, alloy formation, equilibrium shape of mesoscopic crystallites and surface faceting.; Comment: 4 pages, 2 figures

Hole dynamics in noble metals

Campillo, I.; Rubio, A.; Pitarke, J. M.; Goldmann, A.; Echenique, P. M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/08/2000
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48.07326%
We present a detailed analysis of hole dynamics in noble metals (Cu and Au), by means of first-principles many-body calculations. While holes in a free-electron gas are known to live shorter than electrons with the same excitation energy, our results indicate that d-holes in noble metals exhibit longer inelastic lifetimes than excited sp-electrons, in agreement with experiment. The density of states available for d-hole decay is larger than that for the decay of excited electrons; however, the small overlap between d- and sp-states below the Fermi level increases the d-hole lifetime. The impact of d-hole dynamics on electron-hole correlation effects, which are of relevance in the analysis of time-resolved two-photon photoemission experiments, is also addressed.; Comment: 4 pages, 2 figures, to appear in Phys. Rev. Lett

Observation of shell effects in nanowires for the noble metals copper, silver and gold

Mares, A. I.; van Ruitenbeek, J. M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/06/2005
Relevância na Pesquisa
47.6891%
We extend our previous shell effect observation in gold nanowires at room temperature under ultra high vacuum to the other two noble metals: silver and copper. Similar to gold, silver nanowires present two series of exceptionally stable diameters related to electronic and atomic shell filling. This observation is in concordance to what was previously found for alkali metal nanowires. Copper however presents only electronic shell filling. Remarkably we find that shell structure survives under ambient conditions for gold and silver.; Comment: 8 pages, 8 figures

Applications of a tight-binding total energy method for transition and noble metals: Elastic Constants, Vacancies, and Surfaces of Monatomic Metals

Mehl, Michael J.; Papaconstantopoulos, Dimitrios A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.8626%
A recent tight-binding scheme provides a method for extending the results of first principles calculations to regimes involving $10^2 - 10^3$ atoms in a unit cell. The method uses an analytic set of two-center, non-orthogonal tight-binding parameters, on-site terms which change with the local environment, and no pair potential. The free parameters in this method are chosen to simultaneously fit band structures and total energies from a set of first-principles calculations for monatomic fcc and bcc crystals. To check the accuracy of this method we evaluate structural energy differences, elastic constants, vacancy formation energies, and surface energies, comparing to first-principles calculations and experiment. In most cases there is good agreement between this theory and experiment. We present a detailed account of the method, a complete set of tight-binding parameters, and results for twenty-nine of the alkaline earth, transition and noble metals.; Comment: 24 pages (REVTEX), 6 figures (epsf.tex required). Several new results have been added. Re-submitted to Physical Review B

Conductance of a tunnel point-contact of noble metals in the presence of a single defect

Avotina, Ye. S.; Kolesnichenko, Yu. A.; Roobol, S. B.; van Ruitenbeek, J. M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 23/10/2007
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47.899766%
In paper [1] (Avotina et al. Phys. Rev. B,74, 085411 (2006)) the effect of Fermi surface anisotropy to the conductance of a tunnel point contact, in the vicinity of which a single point-like defect is situated, has been investigated theoretically. The oscillatory dependence of the conductance on the distance between the contact and the defect has been found for a general Fermi surface geometry. In this paper we apply the method developed in [1] to the calculation of the conductance of noble metal contacts. An original algorithm, which enables the computation of the conductance for any parametrically given Fermi surface, is proposed. On this basis a pattern of the conductance oscillations, which can be observed by the method of scanning tunneling microscopy, is obtained for different orientations of the surface for the noble metals.; Comment: 8 pages, 5 figures

Theory and computation of hot carriers generated by surface plasmon polaritons in noble metals

Bernardi, Marco; Mustafa, Jamal; Neaton, Jeffrey B.; Louie, Steven G.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em /06/2015
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48.30967%
Hot carriers (HC) generated by surface plasmon polaritons (SPPs) in noble metals are promising for application in optoelectronics, plasmonics and renewable energy. However, existing models fail to explain key quantitative details of SPP-to-HC conversion experiments. Here we develop a quantum mechanical framework and apply first-principles calculations to study the energy distribution and scattering processes of HCs generated by SPPs in Au and Ag. We find that the relative positions of the s and d bands of noble metals regulate the energy distribution and mean free path of the HCs, and that the electron–phonon interaction controls HC energy loss and transport. Our results prescribe optimal conditions for HC generation and extraction, and invalidate previously employed free-electron-like models. Our work combines density functional theory, GW and electron–phonon calculations to provide microscopic insight into HC generation and ultrafast dynamics in noble metals.

Technical and economic aspects of promotion of cobalt-based Fischer-Tropsch catalysts by noble metals - a review

de Beer,M; Kunene,A; Nabaho,D; Claeys,M; van Steen,E
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2014 EN
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The conversion of carbon-containing feedstock into liquid fuels can proceed via the Fischer-Tropsch synthesis, which is catalysed using supported cobalt catalysts. These catalysts contain noble metals to facilitate the reduction of oxidic cobalt species in the catalyst precursor to metallic cobalt, which is the catalytically active species for the Fischer-Tropsch synthesis. This is thought to occur via hydrogen spillover, i.e. the diffusion of atomic hydrogen over the support from the noble metal to the oxidic cobalt moieties. Noble metals may also affect the dispersion of cobalt in the active Fischer-Tropsch catalyst. The economic aspect of the addition of noble metals to the Fischer-Tropsch catalyst is discussed.