CO removal from reformed fuel over Cu/ZnO/Al2O3 catalysts prepared by impregnation and coprecipitation methods

Tanaka, Yohei; Utaka, Toshimasa; Kikuchi, Ryuji; Sasaki, Kazunari; Eguchi, Koichi

doi:10.1016/s0926-860x(02)00095-9

Cited by 95 publications

(55 citation statements)

References 14 publications

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“…4 A composite comprised of CuO, 30 wt % ZnO 20 wt % Al 2 O 3 ͑CuO, 31 mol % ZnO, 16 mol % Al 2 O 3 ͒ was prepared by co-precipitation from aqueous solution. 5,6 Copper, zinc, and aluminum nitrate were dissolved in water ͑total metal concentration of 1 mol/L͒ and added to an aqueous solution of sodium carbonate ͑1.1 mol/L͒. The resulting precipitate was rinsed with deionized water, filtered, and dried in air at 120 ‫ؠ‬ C for 12 h. The dried powder ͑1 g͒ was lightly pressed into the form of a disk, 3.1 mm thick and 15.6 mm in diameter, then calcined at 350 ‫ؠ‬ C for 2 h. This disk was placed adjacent to the anodeside gas diffusion electrode ͑see Fig.…”

Section: Methodsmentioning

confidence: 99%

Alcohol Fuel Cells at Optimal Temperatures

Uda

Boysen

Chisholm

et al. 2006

Electrochem. Solid-State Lett.

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High-power-density alcohol fuel cells can relieve many of the daunting challenges facing a hydrogen energy economy. Here, such fuel cells are achieved using CsH 2 PO 4 as the electrolyte and integrating into the anode chamber a Cu-ZnO/Al 2 O 3 methanol steam-reforming catalyst. The temperature of operation, ϳ250°C, is matched both to the optimal value for fuel cell power output and for reforming. Peak power densities using methanol and ethanol were 226 and 100 mW/cm 2 , respectively. The high power output ͑305 mW/cm 2 ͒ obtained from reformate fuel containing 1% CO demonstrates the potential of this approach with optimized reforming catalysts and also the tolerance to CO poisoning at these elevated temperatures. © 2006 The Electrochemical Society. ͓DOI: 10.1149/1.2188069͔ All rights reserved. In recent years, significant attention has been directed to hydrogen gas as a fuel. However, major barriers remain to the implementation of a hydrogen-based energy economy, not the least of which is the absence of viable hydrogen storage and delivery technologies. Alcohols have stored energy densities several times that of standard compressed hydrogen ͑e.g., 1 L of methanol and ethanol are energetically equivalent to 4.4 and 5.8 L, respectively, of hydrogen gas compressed at 350 atm͒ and thus may address many of the challenges facing hydrogen as a fuel. Like hydrogen, alcohol fuels have the potential for being produced from renewable resources and thereby mitigating the production of carbon dioxide, a major greenhouse gas.1 Yet, unlike hydrogen, they enjoy a well-developed fuel delivery infrastructure ͑second only to gasoline͒.Implementation of alcohol fuels in fuel cells, energy conversion devices that combine the benefits of zero ͑regulated͒ emissions and high efficiency, requires that the fuel cell electrolyte be impermeable to the fuel. In addition, moderate temperature operation is desirable to minimize CO poisoning at the anode and to enhance fuel electrooxidation kinetics. The proton conducting electrolyte, CsH 2 PO 4 , meets exactly these requirements, and the authors have successfully demonstrated elsewhere hydrogen/oxygen fuel cells based on this electrolyte with good long-term stability at operational temperatures of ϳ250°C.2 The present work was undertaken with the aim of developing high power-density CsH 2 PO 4 -based fuel cells operating on methanol. A key innovation involves the incorporation of a steam reforming catalyst for the conversion of methanol to hydrogen ͑and CO 2 ͒ directly in the fuel cell anode chamber. ExperimentalThe overall fuel-cell/reformer structure employed is shown in Fig. 1. The fuel cell portion, the fabrication of which is detailed elsewhere, 3 consisted of a thin layer of CsH 2 PO 4 ͑26-77 m thick͒ sandwiched between two electrocatalyst layers comprised of a mixture of CsH 2 PO 4 , carbon black, electrocatalyst particles, and a fugitive pore-former. This component was, in turn, sandwiched between two porous stainless steel supports which served as gas diffusion electrodes. The electro...

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Section: Methodsmentioning

confidence: 99%

Alcohol Fuel Cells at Optimal Temperatures

Uda

Boysen

Chisholm

et al. 2006

Electrochem. Solid-State Lett.

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“…Isto indica que a presença dos agentes conversores em questão (Fe/C e Cu/C) afe- 20 , mas isto se verifica em temperaturas consideravelmente maiores que aquelas utilizadas nas condições normais de operação da célula PEMFC (85 o C, no presente caso). Por outro lado, os resultados para o eletrodo contendo Mo/C (Figura 5) indicam um desempenho frente a ROH na ausência de CO similar ao do eletrodo convencional.…”

Section: Resultsunclassified

“…7 CO + H 2 O CO 2 + H 2 (6) Apesar dos avanços na área de células a combustível de membrana de troca protônica, o desenvolvimento de novos materiais eletrocatalisadores e sistemas eletródicos mais tolerantes ao CO ainda é imperioso. Assim, neste trabalho foi feito um estudo sistemático do desempenho de eletrodos de difusão de gás com Pt/C na camada catalisadora e contendo potenciais agentes conversores de CO em CO 2 formados por catalisadores dispersos em carbono baseados em Mo e W, que apresentam uma elevada atividade eletrocatalítica para a reação de oxidação de hidrogênio na presença de CO e, também, em Fe e Cu, que em catálise heterogênea são conhecidos catalisadores da reação de WGS 20 .…”

Section: Introductionunclassified

Influência de M/C (M = Mo, Cu, Fe e W) incorporado à camada difusora do eletrodo de difusão de gás frente à reação de oxidação de hidrogênio na presença de CO

Pereira¹,

Pereira²,

Ticianelli³

2007

Quím. Nova

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Recebido em 25/9/06; aceito em 14/2/07; publicado na web 30/7/07 THE EFFECT OF M/C (M = Mo, Cu, Fe AND W) IN THE DIFFUSION LAYER OF GAS DIFFUSION ELECTRODES ON THE HYDROGEN OXIDATION REACTION IN THE PRESENCE OF CARBON MONOXIDE. The performance of proton exchange membrane fuel cells (PEMFC) with Pt-based anodes is drastically lowered when CO-containing hydrogen is used to feed the system, because of the strong adsorption of CO on platinum. In the present work the effects of the presence of a conversion layer of CO to CO 2 composed by several M/C materials (where M = Mo, Cu, Fe and W) in gas diffusion anodes formed by Pt catalysts were investigated. The diffusion layers formed by Mo/C e W/C show good CO-tolerance, and this was attributed to the CO removal by parallel occurrence of the water-gas shift reaction and the so-called bifunctional mechanism.Keywords: PEMFC; carbon monoxide; water-gas shift. INTRODUÇÃOA busca por fontes alternativas de energia é uma tendência mundial e, neste contexto, as células a combustível constituem a mais promissora alternativa para a geração de energia elétrica em substituição aos geradores acionados por motores a combustão. O combustível ideal para as células a combustível com membrana trocadora de prótons (PEMFC -"proton exchange membrane fuel cell") é o hidrogênio puro, mas seu uso é pouco favorecido por causa das dificuldades de armazenamento e manuseio. Mesmo na forma líquida ou ainda na forma de um hidreto metálico, há uma enorme preocupação e severas exigências de medidas de segurança. Uma alternativa a este problema seria que o hidrogênio utilizado na célula fosse produzido "a bordo" ou in loco através da reforma do gás natural, metanol ou etanol. No entanto, o processo de reforma, além de hidrogênio, produz também CO, que se adsorve fortemente sobre a superfície do catalisador convencional de Pt/C (nanopartículas de platina ancorada em carbono), afetando drasticamente o desempenho da célula, mesmo quando traços deste contaminante estão presentes [1][2][3] . Desta forma, a tolerância ao monóxido de carbono é um fator importante na escolha de um catalisador para a oxidação anódica de hidrogênio em células PEMFC alimentadas com o gás reformado.Algumas abordagens significativas têm sido propostas para solucionar o problema de contaminação do eletrodo por CO. Uma destas abordagens está relacionada à presença de um segundo elemento além da Pt, como Ru 4,5 , Sn 6,7 , Mo 8,9 e Os 10,11 , formando ligas ou co-depósitos dispersos em carbono, resultando em um incremento significativo na tolerância ao CO quando comparado ao catalisador que é formado por partículas de platina pura. Vários tipos de mecanismos têm sido adotados para explicar a maior eficiência da eletrooxidação de H 2 contaminado por CO sobre Pt-Ru, dentre os quais destacam-se o mecanismo bifuncional (mecanismo promovido) 12 e o efeito eletrônico (mecanismo intrínseco) 13 . De acordo com o mecanismo bifuncional, a espécie reagente (H 2 ) e o contaminante (CO) adsorvem-se preferencialmente nos átomos de Pt (Equações 1-3 O ...

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“…The Cu-type catalyst is often used at temperatures in the range of 180-300 °C, but has little catalytic activity at lower temperatures, and the reactor is too big. Furthermore, the CO conversion is not more than 90% even using a good Cu-type catalyst due to chemical equilibrium restriction [3]. Thus, the development of catalysts to accelerate the reaction rate at low temperatures below 150 °C is desired to realize an efficient on-site H 2 production system.…”

Section: Introductionmentioning

confidence: 99%

Pre-Reduction of Au/Iron Oxide Catalyst for Low-Temperature Water-Gas Shift Reaction Below 150 °C

et al. 2011

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Low-temperature water-gas shift reaction (WGS) using gold catalyst is expected to be an attractive technique to realize an efficient on-site hydrogen production process. In this paper, Au/Fe 3 O 4 catalysts for promoting the WGS below 150 °C were developed by a preliminary reduction of Au/iron oxide (Fe 3+ ) catalyst utilizing high reactivity of Au nano-particles. The reduction was conducted under a CO, H 2 , or CO/H 2 O stream at either 140 or 200 °C, and the effect of reduction conditions on the characteristics of the Au/Fe 3 O 4 catalyst and on the catalytic activity in WGS at 80 °C was investigated. The reaction progress during the pre-reduction treatment was qualitatively analyzed, and it was found that the iron oxide in Au/Fe 2 O 3 calcined at 200 °C was easily reduced to Fe 3 O 4 phase in all reduction conditions. The reduction conditions affected the characteristics of both Au and iron oxide, but all of the reduced catalysts had small Fe 3 O 4 particles of less than 20 nm with Au particles on the surface. The surface area and content of cationic Au were high in the order of CO, H 2 , CO/H 2 O, and 140, 200 °C. In the WGS test at 80 °C using the developed catalysts, the activities of the catalysts pre-reduced by CO at 140 or 200 °C and by H 2 at 140 °C were very high with 100% CO conversion even at such a low temperature. These results indicated that factors such as higher surface area, crystallized Fe 3 O 4 , and cationic Au content contributed to the catalytic activity. OPEN ACCESSCatalysts 2011, 1 176

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CO removal from reformed fuel over Cu/ZnO/Al2O3 catalysts prepared by impregnation and coprecipitation methods

Cited by 95 publications

References 14 publications

Alcohol Fuel Cells at Optimal Temperatures

Alcohol Fuel Cells at Optimal Temperatures

Influência de M/C (M = Mo, Cu, Fe e W) incorporado à camada difusora do eletrodo de difusão de gás frente à reação de oxidação de hidrogênio na presença de CO

Pre-Reduction of Au/Iron Oxide Catalyst for Low-Temperature Water-Gas Shift Reaction Below 150 °C

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