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Investigation of a Pt3Sn/C Electro-Catalyst in a Direct Ethanol Fuel Cell Operating at Low Temperatures for Portable Applications

Zignani, S. C.; Gonzalez, E. R.; Baglio, V.; Siracusano, S.; Arico, A. S.
Fonte: ELECTROCHEMICAL SCIENCE GROUP; BELGRADE Publicador: ELECTROCHEMICAL SCIENCE GROUP; BELGRADE
Tipo: Artigo de Revista Científica
Português
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A 20% Pt3Sn/C catalyst was prepared by reduction with formic acid and used in a direct ethanol fuel cell at low temperatures. The electro-catalytic activity of this bimetallic catalyst was compared to that of a commercial 20% Pt/C catalyst. The PtSn catalyst showed better results in the investigated temperature range (30 degrees-70 degrees C). Generally, Sn promotes ethanol oxidation by adsorption of OH species at considerably lower potentials compared to Pt, allowing the occurrence of a bifunctional mechanism. The bimetallic catalyst was physico-chemically characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. The presence of SnO2 in the bulk and surface of the catalyst was observed. It appears that SnO2 can enhance the ethanol electro-oxidation activity at low potentials due to the supply of oxygen-containing species for the oxidative removal of CO and CH3CO species adsorbed on adjacent Pt active sites.; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)

Direct ethanol fuel cell: Electrochemical performance at 90 degrees C on Pt and PtSn/C electrocatalysts

Purgato, F. L. S.; Pronier, S.; Olivi, P.; Andrade, A. R. de; Leger, J. M.; Tremiliosi Filho, Germano; Kokoh, K. B.
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
Português
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Carbon-supported Pt-based electrocatalysts were synthesized by Pechini method for the ethanol oxidation (EOR). Physicochemical characterizations were helpful to estimate the diameters of the obtained materials ranging from 2 nm to 5 nm. Main electrochemical experiments were carried out at 90 degrees C i.e. under the working conditions of performing the single 5 cm(2) direct ethanol fuel cell (DEFC). Pt(80)Sn(20)/C was the anode catalyst which has given the highest power density of 37 mW cm(-2). Importantly, the IR spectroscopy measurements associated with the qualitative analysis done at the output of the anodic compartment of the fuel cell have shown that ethanol oxidation on Pt(80)Sn(20)/C was mainly a two-electron sustainable process. (C) 2011 Elsevier B.V. All rights reserved.; CAPES/COFECUB [498/05]; CAPESCOFECUB; CAPES; CAPES [0509078]

Performance and selectivity of PtxSn/C electro-catalysts for ethanol oxidation prepared by reduction with different formic acid concentrations

Zignani, Sabrina C.; Baglio, Vincenzo; Linares, Jose J.; Monforte, Giuseppe; Gonzalez, Ernesto R.l; Arico, Antonino S.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD; OXFORD Publicador: PERGAMON-ELSEVIER SCIENCE LTD; OXFORD
Tipo: Artigo de Revista Científica
Português
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Carbon supported Pt-Sn catalysts were prepared by reduction of Pt and Sn precursors with formic acid and characterized in terms of structure, morphology and surface properties. The electrocatalytic activity for ethanol oxidation was studied in a direct ethanol fuel cell (DEFC) at 70 degrees C and 90 degrees C. Electrochemical and physico-chemical data indicated that a proper balance of Pt and Sn species in the near surface region was necessary to maximize the reaction rate. The best atomic surface composition, in terms of electrochemical performance, was Pt:Sn 65:35 corresponding to a bulk composition 75:25 namely Pt3Sn1/C. The reaction products of ethanol electro-oxidation in single cell and their distribution as a function of the nature of catalyst were determined. Essentially, acetaldehyde and acetic acid were detected as the main reaction products; whereas, a lower content of CO2 was formed. The selectivity toward acetic acid vs. acetaldehyde increased with the increase of the Sn content and decreased by decreasing the concentration of the reducing agent used in the catalyst preparation. According to the recent literature, these results have been interpreted on the basis of ethanol adsorption characteristics and ligand effects occurring for Sn-rich electrocatalysts. (C) 2012 Elsevier Ltd. All rights reserved.; Fundacao de Apoio a Pesquisa do Estado de Sao Paulo (FAPESP) [2010/07108-3]; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) [Proc. 310151/2008-2]; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)

Preparação, caracterização e aplicação de catalisadores trimetálicos para a oxidação de etanol em célula a combustível direta: Pt-Ru-Sn/C; Preparation, characterization, and application of trimetalic catalysts for direct ethanol fuel cells: Pt-Ru-Sn/C

Cunha, Émerson Maran da
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 29/11/2007 Português
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Este trabalho teve o intuito de desenvolver um método para a preparação de nanocatalisadores de Platina modificada com Rutênio e Estanho suportados em Carbono para a eletrooxidação de etanol em célula à combustível direta. O método utilizado que consistiu na decomposição de precursores poliméricos. Diversos nanocatalisadores foram preparados, sempre variando-se a proporção entre Platina, Rutênio e Estanho, e a proporção Carbono/Metal foi mantida constante em 60/40%. Para a caracterização físico-química desses nanocatalisadores, foram utilizadas as técnicas de Difração de Raios X (DRX), Microscopia Eletrônica de Transmissão (MET) e Espectroscopia de Energia Dispersiva de Raios X (EDX), e os resultados mostraram que o tamanho de cristalito ficou próximo a 7 nm para os nanocatalisadores bimetálicos e 5,8 nm para os nanocatalisadores trimetálicos, a composição experimental ficou próxima da composição nominal, a distribuíção de partículas de metais sobre o Carbono foi bastante heterogênea. Para a caracterização eletroquímica dos nanocatalisadores, foram empregadas as técnicas de Voltametria Cíclica (VC) e Cronoamperometria, e após as Eletrólises, empregada a técnica de Cromatografia Líquida de Alta Eficiência (CLAE). O produto majoritário encontrado foi o acetaldeído...

Preparação de eletrocatalisadores PtSnCu/C e PtSn/C e ativação por processos de Dealloying para aplicação na oxidação eletroquímica do Etanol; Preparation of PtSnCu/C and PtSn/C electrocatalysts and activation by dealloying processes for ethanol electro-oxidation

Crisafulli, Rudy
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 08/02/2013 Português
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Foram preparados eletrocatalisadores PtSnCu/C (com diferentes razões atômicas Pt:Sn:Cu) e PtSn/C (50:50) com 20 % em massa de metais pelos métodos da redução por borohidreto (IRB) e redução por álcool (RA). Utilizou-se H2PtCl6.6H2O, SnCl2.2H2O e CuCl2.2H2O como fonte de metais, NaBH4 e etilenoglicol como agentes redutores, 2-propanol e etilenoglicol/água como solventes e carbono como suporte. Numa segunda etapa, estes eletrocatalisadores foram ativados pelos processos de dealloying químico (DQ), por tratamento com HNO3 e dealloying eletroquímico (DE), utilizando a técnica de eletrodo de camada fina porosa. Os materiais obtidos foram caracterizados por energia dispersiva de raios-X (EDX), difração de raios-X (DRX), microscopia eletrônica de transmissão (MET), energia dispersiva de raios-X de varredura linear (EDX-VL) e voltametria cíclica (VC). Estudos eletroquímicos para a oxidação eletroquímica do etanol foram realizados por voltametria cíclica, cronoamperometria e células unitárias (conjunto eletrodos/membrana). Os efluentes anódicos provenientes dos testes em células unitárias foram analisados por cromatografia a gás de alta eficiência (CG). Os difratogramas de raios-X dos eletrocatalisadores sintetizados mostraram a típica estrutura cúbica de face centrada (CFC) de liga de platina e após tratamento por dealloying...

Estudo da eletro-oxidação do etanol utilizando eletrocatalisadores PtPd/C+ATO e PtPdSn/C+ATO preparados via redução por borohidreto de sódio; Study on ethanol electro-oxidation using PtPd/C+ATO and PtPdSn/C+ATO catalysts prepared by the reduction by sodium borohydride method

Piasentin, Ricardo Marcelo
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 25/06/2013 Português
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Em uma primeira etapa, os catalisadores eletroquímicos de Pt/C, Pt/C+ATO, Pd/C, Pd/C+ATO, PtPd/C+ATO e PtPdSn/C+ATO, onde foram usadas diferentes razões molares de Pt e Pd, e de Pt, Pd e Sn, respectivamente, foram preparados pelo método de redução por borohidreto de sódio para serem testados na oxidação do etanol. H2PtCl6.6H2O, Pd(NO3)2.2H2O e SnCl2.2H2O foram utilizados como fontes de metais, que corresponderam a 20% em massa do catalisador. A mistura física de 85% de carbono Vulcan XC72 e 15% de Sb2O5.SnO2 (ATO) foi utilizada como suporte. Os catalisadores foram caracterizados por meio da difração de raios X, microscopia de transmissão, voltametria cíclica, cronoamperometria, teste em célula unitária de etanol direto e espectroscopia de infravermelho com transformada de Fourier in situ (ATR-FTIR). Os difratogramas de raios X de Pt/C e Pd/C mostraram quatro picos associados com a estrutura cúbica de face centrada (cfc) da platina e do paládio, respectivamente. Já para os catalisadores de Pt, Pd, PtPd e PtPdSn, suportados em carbono e ATO puderam ser visualizados, além dos picos referentes à Pt e ao Pd, outros oito picos associados com a cassiterita e/ou com os óxidos de estanho dopado com antimônio (ATO). A microscopia de transmissão mostrou que todos os catalisadores apresentam suas partículas metálicas homogeneamente distribuídas no suporte e seus tamanhos variaram de 2 a 6 nm. Os estudos eletroquímicos de voltametria e cronoamperometria em meio de H2SO4 indicaram que os catalisadores terciários de PtPdSn(80:10:10)/C+ATO e PtPdSn(90:5:5)/C+ATO...

A solid paraffin-based carbon paste electrode modified with 2-aminothiazole organofunctionalized silica for differential pulse adsorptive stripping analysis of nickel in ethanol fuel

Takeuchi, Regina M.; Santos, Andre L.; Padilha, Pedro M.; Stradiotto, Nelson R.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 295-301
Português
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A solid paraffin-based carbon paste electrode modified with 2-aminothiazole organofunctionalized silica (SiAt-SPCPE) was applied to Ni2+ determination in commercial ethanol fuel samples. The proposed method comprised four steps: (1) Ni2+ preconcentration at open circuit potential directly in the ethanol fuel sample, (2) transference of the electrode to an electrochemical cell containing DMG, (3) differential pulse voltammogram registering and (4) surface regeneration by polishing the electrode. The proposed method combines the high Ni2+ adsorption capacity presented by 2-aminothiazole organofunctionalized silica with the electrochemical properties of the Ni(DMG)2 complex, whose electrochemical reduction provides the analytical signal.All experimental parameters involved in the proposed method were optimized. Using a preconcentration time of 20 min, it was obtained a linear range from 7.5 x 10(-9) to 1.0 x 10(-6) mol L-1 with detection limit of 2.0 x 10(-9) mol L-1. Recovery values between 96.5 and 102.4% were obtained for commercial samples spiked with 1.0 mu mol L-1 Ni2+ and the developed electrode was totally stable in ethanolic solutions. The contents of Ni2+ found in the commercial samples using the proposed method were compared to those obtained by graphite furnace atomic absorption spectroscopy by using the F- and t-test. Neither the F- nor t-values exceeded the critical values at 95% confidence level...

Copper determination in ethanol fuel by differential pulse anodic stripping voltammetry at a solid paraffin-based carbon paste electrode modified with 2-aminothiazole organofunctionalized silica

Takeuchi, Regina M.; Santos, Andre L.; Padilha, Pedro M.; Stradiotto, Nelson R.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 771-777
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Solid paraffin-based carbon paste electrodes modified with 2-aminothiazole organofunctionalized silica have been applied to the anodic stripping determination of copper ions in ethanol fuel samples without any sample treatment. The proposed method comprised four steps: (1) copper ions preconcentration at open circuit potential directly in the ethanol fuel sample; (2) exchange of the solution and immediate cathodic reduction of the absorbate at controlled potential; (3) differential pulse anodic stripping voltammetry; (4) electrochemical surface regeneration by applying a positive potential in acid media. Factors affecting the preconcentration, reduction and stripping steps were investigated and the optimum conditions were employed to develop the analytical procedure. Using a preconcentration time of 20 min and reduction time of 120 s at -0.3 V versus Ag/AgCl(sat) a linear range from 7.5 x 10(-8) to 2.5 x 10(-6) mol L(-1) with detection limit of 3.1 x 10(-8) mol L(-1) was obtained. Interference studies have shown a decrease in the interference effect according to the sequence: Ni > Zn > Cd > Pb > Fe. However, the interference effects of these ions have not forbidden the application of the proposed method. Recovery values between 98.8 and 102.3% were obtained for synthetic samples spiked with known amounts of Cu(2+) and interfering metallic ions. The developed electrode was successfully applied to the determination of Cu(2+) in commercial ethanol fuel samples. The results were compared to those obtained by flame atomic absorption spectroscopy by using the F-test and t-test. Neither F-value nor t-value have exceeded the critical values at 95% confidence level...

Copper determination in ethanol fuel samples by anodic stripping voltammetry at a gold microelectrode

Takeuchi, Regina M.; Santos, Andre L.; Medeiros, Maria J.; Stradiotto, Nelson R.
Fonte: Springer Wien Publicador: Springer Wien
Tipo: Artigo de Revista Científica Formato: 101-106
Português
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 03/05567-7; Processo FAPESP: 03/09334-7; A linear sweep anodic stripping voltammetric method was developed for copper determination in commercial ethanol fuel samples by using a gold microelectrode. Under the optimized conditions, a linear range from 0.05 to 1.0 mu M was obtained, with detection limit of 22 nM. The method was employed to determine copper ions in six commercial ethanol fuel samples and the results were compared with those obtained by FAAS. This study showed that for most samples both methods produced concordant results. However, for two samples, copper is distributed in its labile and complexed forms leading to copper contents contrasting with those obtained by flame atomic absorption spectroscopy (FAAS). It was observed that acidification of the samples is a very efficient way to recover copper from its complexed forms. After acidification, the copper contents obtained were concordant with those obtained by FAAS. Thus, the method can be employed to the reliable copper determination in commercial ethanol fuel samples. Moreover, this is the first work providing some insights about copper speciation in commercial ethanol fuel samples.

Simultaneous determination of Cu and Pb in fuel ethanol by graphite furnace AAS using tungsten permanent modifier with co-injection of Ir

Santos, Luana Novaes; Gomes Neto, Jose Anchieta; Caldas, Naise Mary
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica
Português
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58.22526%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); A method has been developed for the simultaneous determination of Cu and Pb in ethanol fuel by GF AAS using a transversely heated graphite atomizer (THGA) with W permanent modifier and co-injection of Ir. Pyrolysis and atomization temperature curves were established in fuel ethanol medium (1 + 1; v/v) containing 1.0% (v/v) HNO3 and spiked with 20 mu g L-1 Cu and Pb. For 20 mu L of diluted sample (10 mu L ethanol + 10 mu L of 2.0 % (v/v) HNO3) dispensed into the graphite tube, analytical curves in the 5.0-25 mu g L-1 Cu and 10-50 mu g L-1 Pb ranges were established. The calculated characteristic masses were 18 pg for Cu and 36 pg for Pb. The limits of detection (LOD) based on integrated absorbance were 0.086 mu g L-1 and 2.47 mu g L-1 for Cu and Pb, respectively. The recoveries of the spiked samples varied from 93-103% (Cu) and 96-110% (Pb). The relative standard derivations (n = 12) were <= 0.5 Cu and <= 0.7 Pb. Accuracy was checked for Cu and Pb determination in 10 samples purchased at local gas stations in Brazil. The found concentrations varied from 8.0 to 47 mu g L-1 Cu. All the analyzed samples presented Pb contents below the limit of detection of this method. These amounts are considered acceptable for the Brazilian regulatory agency for hydrated fuel ethanol. (C) 2012 Elsevier Ltd. All rights reserved.

Evaluation of water amount in hydrated ethanol fuel by gamma-ray attenuation technique

De Oliveira Jr., José M.; Silva, Ítalo C. O.; Malaquias, Bruno R.; Martins, Antonio C. G.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 275-279
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In this work, is presented an alternative and non conventional technique for evaluate the water amount present in the hydrated ethanol used as automotive fuel. The standard technique used in this kind of measure is the use of densimeter. The proposal of this work is based on the measure of the linear attenuation coefficient of hydrated ethanol, using the gamma-ray attenuation technique. The water amount, in volume, can be determined knowing the linear attenuation coefficient of hydrated ethanol. Samples of hydrated ethanol, collected at fuel stations, located in Sorocaba, SP, Brazil, were analyzed and the results showed the feasibility of the technique. © 2011 American Institute of Physics.

Voltammetric determination of ethyl acetate in ethanol fuel using a Fe 3+/Nafion®-coated glassy carbon electrode

Caetano, Lahys G.; Takeuchi, Regina M.; Santos, André L.; De Oliveira, Marcelo F.; Stradiotto, Nelson R.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 837-842
Português
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A voltammetric method for the determination of ethyl acetate in ethanol fuel using a Fe3+/Nafion®-coated glassy carbon electrode (GCE) is proposed. The ethyl acetate present in the ethanol fuel was previously converted to acetohydroxamic acid via pretreatment with hydroxylamine chloride. The acetohydroxamic acid promptly reacted with the iron (III) present in the film, producing iron (III) acetohydroxamate, which presents a well-defined voltammetric peak current at -0.02 V. Optimization of the voltammetric parameters for the cyclic, linear sweep, square wave, and differential pulse modalities was carried out for this chemically-modified electrode. Square wave voltammetry afforded the best response for acetohydroxamic acid detection. The analytical curve for this species was linear from 9 to 100 μmol L 1 according to the following equation: ip (μA) = 0.27 + 2.55Cacetohydroxamic acid (μmol L 1), with linear correlation coefficient equal to 0.993. The technique presented limit of detection equal to 5.3 μmol L 1 and quantification limit of 17.6 μmol L 1. The proposed method was compared to the official method of ethyl acetate analysis (Gas Chromatography), and a satisfactory correlation was found between these techniques. © 2012 Elsevier Ltd. All rights reserved.

The electro-oxidation of carbon monoxide and ethanol on supported Pt nanoparticles: The influence of the support and catalyst microstructure

Ciapina, Eduardo G.; Santos, Sydney F.; Gonzalez, Ernesto R.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1831-1842
Português
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The sluggish kinetics of ethanol oxidation on Pt-based electrodes is one of the major drawbacks to its use as a liquid fuel in direct ethanol fuel cells, and considerable efforts have been made to improve the reaction kinetics. Herein, we report an investigation on the effect of the Pt microstructure (well-dispersed versus agglomerated nanoparticles) and the catalyst support (carbon Vulcan, SnO2, and RuO2) on the rate of the electrochemical oxidation of ethanol and its major adsorbed intermediate, namely, carbon monoxide. By using several structural characterization techniques such as X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy, along with potentiodynamic and potentiostatic electrochemical experiments, we show that by altering both the Pt microstructure and the support, the rate of the electrochemical oxidation of ethanol can be improved up to a factor of 12 times compared to well-dispersed carbon-supported Pt nanoparticles. As a result of a combined effect, the interaction of Pt agglomerates with SnO2 yielded the highest current densities among all materials studied. The differences in the activity are discussed in terms of structural and electronic properties as well as by mass transport effects...

Ethanol electro-oxidation in an alkaline medium using Pd/C, Au/C and PdAu/C electrocatalysts prepared by electron beam irradiation

Geraldes, Adriana Napoleão; Da Silva, Dionisio Furtunato; Pino, Eddy Segura; Da Silva, Júlio César Martins; De Souza, Rodrigo Fernando Brambilla; Hammer, Peter; Spinacé, Estevam Vitório; Neto, Almir Oliveira; Linardi, Marcelo; Dos Santos, Mauro Coelh
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 455-465
Português
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Carbon-supported Pd, Au and bimetallic PdAu (Pd:Au 90:10, 50:50 and 30:70 atomic ratios) electrocatalysts were prepared using electron beam irradiation. The obtained materials were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their catalytic activities toward ethanol electro-oxidation were evaluated in an alkaline medium using electrochemical techniques, in situ attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) analysis and a single alkaline direct ethanol fuel cell (ADEFC). EDX analyses showed that the actual Pd: Au atomic ratios were very similar to the nominal ones. X-ray diffractograms of PdAu/C electrocatalysts evidenced the presence of Pd-rich (fcc) and Au-rich (fcc) phases. TEM analysis showed a homogeneous dispersion of nanoparticles on the carbon support, with an average size in the range of 3-5 nm and broad size distributions. Cyclic voltammetry (CV) and chronoamperometry (CA) experiments revealed the superior ambient activity toward ethanol electro-oxidation of PdAu/C electrocatalysts with Pd: Au ratios of 90:10 and 50:50. In situ ATR-FTIR spectroscopy measurements have shown that the mechanism for ethanol electro-oxidation is dependent on catalyst composition...

Simultaneous Determination of Iron and Copper in Ethanol Fuel Using Nafion/Carbon Nanotubes Electrode

Silva, Josiel J.; Paim, Leonardo L.; Stradiotto, Nelson R.
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 1794-1800
Português
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 11/16186-0; Processo FAPESP: 12/00258-5; This work presents the analytical method development for iron and copper determination in ethanol fuel. This method was developed using stripping voltammetry with a glassy carbon electrode modified with Nafion/Carbon-nanotubes. With linear sweep stripping voltammetry was achieved a limit of detection of 7.1 x 10(-7) mol L-1 for Fe3+ and 5.1 x 10(-8) mol L-1 for Cu2+. The amperometric sensitivities were 2.0 x 10(6) mu A mol(-1) L for Fe3+ and 2.8 x 10(7) mu A mol(-1) L for Cu2+. The recovery study showed that the method has good accuracy and repeatability, with recovery of 108 and 103% for Fe3+ and Cu2+ respectively.

Determination of sulfate in ethanol fuel using an electrode chemically modified with polypyrrole by flow injection analysis

Castilho, Michelle de Souza; Yamanaka, Hideko; Oliveira, Marcelo Firmino de; Zanoni, Maria Valnice Boldrin; Stradiotto, Nelson Ramos
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 220-227
Português
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In this work, an electrode chemically modified with polypyrrole (PCME) was employed for determination of sulfate in ethanol fuel using a FIA system. The PCME was prepared by polymerization of pyrrole at a glassy carbon electrode by means of cyclic voltammetry technique. An analytical curve from 1.0 x 10−5 to 8.0 x 10−5 mol L−1 was obtained in flow injection system based on the PCME. An amperometric sensibility of 2.3 x 10−3 A mol−1 L and a detection limit of 2.5 x 10−6 mol L−1 were achieved. The proposed method was employed for determination of sulfate ions in commercial samples of ethanol fuel. The results were in good agreement with those obtained by the ionic chromatographic method.

Alternativa para aumentar a produção mundial do etanol anidro combustivel no curto prazo : o potencial dos meis da cana; Alternative to increase the anhydrous ethanol fuel worldwide production in short term : the potencial of surgarcane molasses

Juan Arturo Castaneda Ayarza
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 13/07/2007 Português
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o objetivo principal desta dissertação é mostrar o potencial dos méis da cana-de-açúcar na produção do etanol combustível nos principais países industrializadores da cana, visando aumentar, no curto prazo, a oferta mundial do etanol anidro para ser misturado à gasolina. A partir do cálculo do potencial dos méis da cana foi analisado o impacto que teria o aumento de produção do etanol no mercado interno e externo do açúcar nos países pesquisados, assim como as perspectivas do incipiente mercado internacional do etanol combustível, através da projeção da demanda de gasolina e da análise dos programas que apóiam o uso e a produção dos biocombustíveis. Assim, através da projeção da demanda potencial por etanol dos países consumidores, estimar que vários dos paises industrializadores da cana estudados teriam possibilidades de produzir em média 1 bilhão de litros de etanol anidro por ano no curto prazo, e que o comércio internacional de etanol, embora atualmente esteja sustentado pelos acordos de comércio internacional e por acordos bilaterais, tem possibilidades de aumentar seus fluxos à mercê do rápido crescimento da demanda mundial. Finalmente, concluímos que a cana-de-açúcar e a sua indústria têm possibilidades de impulsionar no curto prazo e até sustentar o desenvolvimento de um novo mercado internacional de etanol combustível; The main objective of this dissertation is to show the potential of the molasses from sugarcane...

An anionic resin modified by di-2-pyridyl ketone salicyloylhydrazone as a new solid preconcentration phase for copper determination in ethanol fuel samples

Garcia,Samara; Gaubeur,Ivanise
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2011 Português
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The adsorption of DPKSH onto anionic resin was investigated at 25 ± 1 ºC and pH 12 on the basis of three kinetic models including pseudo-first order, pseudo-second order and intraparticle diffusion. Isotherm equations including Langmuir, Freundlich and Dubinin-Radushkevich (D-R) were successfully applied to model the experimental data. An anionic resin loaded with DPKSH was used in a flow system for the in-line concentration of copper prior to spectrophotometric determination. Under optimized conditions, a linear response was observed between 20 and 80 µg L-1, with limits of detection and quantification estimated at 0.5 and 1.8 µg L-1, respectively, at the 95% confidence level with an enrichment factor of 11. The relative standard deviation was estimated to be 2.6% for 32 µg L-1 Cu(II) (n = 20). The results obtained for copper determination in ethanol fuel samples agreed with those achieved by flame atomic absorption spectrometry (F AAS) at the 99% confidence level.

A simple and fast procedure for in situ determination of water in ethanol fuel

Ribeiro,Mauricio S.; Angnes,Lúcio; Rocha,Fábio R. P.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2013 Português
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A simple and inexpensive procedure, based on the high difference in solubility of sodium chloride in ethanol and water, is proposed to estimate the water content in ethanol fuel. The ionic concentration of solutions saturated with the salt is monitored by conductometric measurements with a linear response up to 16% water in an alcoholic medium and a limit of detection of 0.05% (v/v). The procedure is precise (coefficient of variation of 0.6%, n = 10) and accurate (results in agreement with those obtained by Karl Fischer amperometric titration at the 95% confidence level). An indicating electronic device exploiting the same principle was proposed for in situ monitoring of ethanol fuel samples aiming at the fast detection of unconformities. The device can be operated by nonexperts, generating a binary response indicated by coloured LEDs, and it successfully classified commercial samples spiked with different amounts of water.

Unintended consequences of ethanol production: Geospatial lifecycle analysis

Malone, Amanda Louise
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
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Ethanol use has been lauded as a way to provide a secure, diverse, environmentally friendly and economically beneficial energy supply for the US. However, along with this praise has been criticism due to potential unintended consequences that may arise from ethanol production and use. This thesis addresses one such unintended consequence: the displacement of emissions from downstream vehicle operation locations to upstream farming and production areas. The thesis uses the Upstream Ethanol Production (UEP) Model, a geospatial lifecycle model developed for analyzing spatial emissions inventories for ethanol production. The UEP model is based on the US GREET model – the gold standard for total fuel cycle analysis models in the U.S. The UEP allows for key pollutants including CO2, N2O, CH4, CO, VOCs, SOx, NOx and PM to be quantified at various locations throughout the ethanol production pathway Several case studies involving ethanol fuel use in New York State are used to demonstrate the model and explore the upstream versus downstream air emissions associated with the ethanol production pathway. The results indicate the importance of transportation and distribution pathways, as well as feedstock production assumptions, on the overall geospatial impacts of air pollution. Displaced emissions from downstream vehicle operation locations in urban areas to upstream feedstock and ethanol fuel production locations in rural areas are also shown by the results. The results indicate that the use of ethanol at urban areas such as those in New York State to reduce greenhouse gases come at the expense of the rural area air quality. Based on the results...