Novas estratégias no estudo da eletro-oxidação de etanol: nanocatalisadores multimetálisos e análises dos produtos de reação
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Data
2013-05-20
Autores
Santos, Nathalia Abe [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Nesse trabalho foi realizado um estudo comparativo das propriedades físicas e eletrônicas e das atividades catalíticas para a oxidação de etanol de nanopartículas bi e trimetálicas suportadas em pó de carbono. Para a obtenção dos catalisadores as nanopartículas foram preparadas inicialmente em estado coloidal pelo método de poliol e posteriormente suportadas em carbono (Vulcan XC-72), utilizando quantidades adequadas para obter catalisadores com composição metal:carbono de 20:80 (em massa). Nanopartículas dos sistemas binários e ternários PtSn, PtRh, PtRu, PtSnRu e PtSnRh com composições atômicas nominais 70:30 e 70:15:15, respectivamente, foram preparadas misturando-se os precursores metálicos no início da síntese. Os sistemas ternários PtSn-PtRh e PtSn-PtRu foram sintetizados pela mistura de nanopartículas bimetálicas em estado coloidal antes da etapa de suporte em carbono. Os catalisadores foram caracterizados por difração de raios X (DRX), microscopia eletrônica de transmissão (TEM) e espectroscopia de absorção de raios X (DXAS). O comportamento eletroquímico geral dos catalisadores foi avaliado por voltametria cíclica em solução de H2SO4 (0,5 mol L-1). A atividade catalítica para a oxidação de etanol foi avaliada por varreduras de potencial e cronoamperometria em solução ácida de etanol (0,5 mol L-1). Para a avaliação das áreas dos catalisadores foram realizadas medidas de oxidação de CO adsorvido. Experimentos de espectroscopia no infravermelho in situ (FTIRAS in situ) foram realizados para verificar a distribuição dos produtos da reação de oxidação de etanol. O estudo mostrou que os catalisadores têm atividades catalíticas significativamente diferentes tanto para a oxidação de etanol quanto para a oxidação de CO adsorvido, sendo o material PtSn/C o mais ativo para...
In this work, a comparative study of physical and electronic properties and catalytic activities for ethanol oxidation of carbon-supported binary and ternary metallic nanoparticles was carried out. For the catalysts, the nanoparticles were initially synthesized in colloidal state by a polyol method and subsequently supported on carbon powder (Vulcan XC-72) in amounts adequate to obtain catalysts with nominal composition metal:carbon 20:80 (in mass). The nanoparticles of the binary and ternary systems PtSn, PtRh, PtRu, PtSnRu and PtSnRh with nominal atomic compositions 70:30 and 70:15:15, respectively, were prepared from the mixture of the metal precursors at the beginning of the synthesis. The ternary systems PtSn-PtRh and PtSn-PtRu were synthesized by mixing the binary nanoparticles in colloidal state before the supporting step. The catalysts were characterized by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and Dispersive X-ray absorption spectroscopy (DXAS). The general electrochemical behavior was evaluated by cyclic voltammetry in H2SO4 solution (0.5 mol L-1). The catalytic activity for ethanol oxidation was evaluated by potential sweeps and chronoamperometry in acid solutions of ethanol (0.5 mol L-1). Experiments of oxidation of adsorbed CO were done for the evaluation of the catalysts active areas. Infrared spectroscopy (FTIRAS in situ) measurements were performed to study the product distribution of the ethanol oxidation reaction. All these studies showed that the catalysts have catalytic activities substantially different for ethanol oxidation reaction as well as for the oxidation of adsorbed CO, and that while the PtSn/C catalyst is the most active for ethanol oxidation PtSnRh/C and PtSnRu/C are more effective for CO oxidation. FTIRAS measurements evidenced formation of adsorbed CO for PtRh/C indicating... (Complete abstract click electronic access below)
In this work, a comparative study of physical and electronic properties and catalytic activities for ethanol oxidation of carbon-supported binary and ternary metallic nanoparticles was carried out. For the catalysts, the nanoparticles were initially synthesized in colloidal state by a polyol method and subsequently supported on carbon powder (Vulcan XC-72) in amounts adequate to obtain catalysts with nominal composition metal:carbon 20:80 (in mass). The nanoparticles of the binary and ternary systems PtSn, PtRh, PtRu, PtSnRu and PtSnRh with nominal atomic compositions 70:30 and 70:15:15, respectively, were prepared from the mixture of the metal precursors at the beginning of the synthesis. The ternary systems PtSn-PtRh and PtSn-PtRu were synthesized by mixing the binary nanoparticles in colloidal state before the supporting step. The catalysts were characterized by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and Dispersive X-ray absorption spectroscopy (DXAS). The general electrochemical behavior was evaluated by cyclic voltammetry in H2SO4 solution (0.5 mol L-1). The catalytic activity for ethanol oxidation was evaluated by potential sweeps and chronoamperometry in acid solutions of ethanol (0.5 mol L-1). Experiments of oxidation of adsorbed CO were done for the evaluation of the catalysts active areas. Infrared spectroscopy (FTIRAS in situ) measurements were performed to study the product distribution of the ethanol oxidation reaction. All these studies showed that the catalysts have catalytic activities substantially different for ethanol oxidation reaction as well as for the oxidation of adsorbed CO, and that while the PtSn/C catalyst is the most active for ethanol oxidation PtSnRh/C and PtSnRu/C are more effective for CO oxidation. FTIRAS measurements evidenced formation of adsorbed CO for PtRh/C indicating... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Físico-química, Eletrocatálise, Nanopartículas, Nanoparticles
Como citar
SANTOS, Nathalia Abe. Novas estratégias no estudo da eletro-oxidação de etanol: nanocatalisadores multimetálisos e análises dos produtos de reação. 2013. 85 f. Dissertação (mestrado) - Universidade Estadual Paulista Júlio de Mesquita Filho, Instituto de Química de Araraquara, 2013.