Study of active sites and mechanism responsible for highly selective CO oxidation in H2 rich atmospheres on a mixed Cu and Ce oxide catalyst

Polster, Christopher S.; Nair, Hari; Baertsch, Chelsey D.

doi:10.1016/j.jcat.2009.06.021

Cited by 180 publications

(134 citation statements)

References 25 publications

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“…Thus, differences between the CO oxidation activities under CO-PROX conditions for this type of catalyst is related to the extent of support promotion of such partial (to Cu + ) CuO reduction at interfacial sites which is attained in each case. It is worth noting that the correlation between the intensity of the Cu + -carbonyl and CO oxidation activity over samples of this type was also independently demonstrated later by Baertsch et al [63]. On the other hand, the reaction mechanism under which this type of catalyst operates for CO oxidation has been proposed to be of a redox, generally speaking, of the Mars-van Krevelen [64,65], type [6].…”

Section: Nature Of Active Sites/entities and Further Hints On Catalytmentioning

confidence: 68%

Characterization of Active Sites/Entities and Redox/Catalytic Correlations in Copper-Ceria-Based Catalysts for Preferential Oxidation of CO in H2-Rich Streams

et al. 2013

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This article reviews work done at authors' laboratories about catalysts based on combinations between copper and ceria for preferential oxidation of CO in H 2 -rich streams (CO-PROX). The main focus of this review is the characterization of active sites for the process on the basis of spectroscopic analysis of the systems under reaction conditions (operando techniques). On such a basis, it is exposed the state of the art in this field in connection with results obtained in other laboratories. OPEN ACCESSCatalysts 2013, 3 379 Keywords: copper-ceria catalysts; CO preferential oxidation (CO-PROX); diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS); X-ray absorption near edge spectroscopy (XANES); Raman; X-ray diffraction (XRD); X-ray photoelectron spectroscopy (XPS)

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Section: Nature Of Active Sites/entities and Further Hints On Catalytmentioning

confidence: 68%

Characterization of Active Sites/Entities and Redox/Catalytic Correlations in Copper-Ceria-Based Catalysts for Preferential Oxidation of CO in H2-Rich Streams

et al. 2013

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“…The isotherm of the catalysts at different wt% CU loading reveals a typical type IV sorption behavior, representing the predominant mesoporous structure characteristic as shown in Figure 2. The volume of N 2 adsorbed on the catalyst surface decreases with increasing CuO up to 40 wt%, which indicates that coverage of CuO decreases the specific surface area of the sample [9].The S BET of CuO/CeO 2 -Co 3 O 4 catalysts were calculated by Brunauer EmmettTeller (BET) method using data from N 2 adsorptiondesorption isotherm with in between 0.05-0.35 and the results are reported in Table 1.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

Effect of Cu Loading to Catalytic Selective CO Oxidation of CuO/CeO2 –Co3O4

Aunbamrung¹,

Wongkaew²

2013

ACES

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This work studied CuO/CeO 2 -Co 3 O 4 with wt% Ce:Co ratio 95:5 for selective CO oxidation with effect of wt% Cu loading. The catalysts were prepared by co-precipitation. Characterizations of catalysts were carried out by XRD and BET techniques. The results showed a good dispersion of CuO for 5 wt% Cu loading catalysts and showed high specific surface area of catalyst. For selective CO oxidation, both 5CuO and 30CuO catalysts could remove completely CO in the presence of excess hydrogen at 423 K and 20CuO could eliminate CO completely at 443 K. Moreover, considering the selectivity to CO oxidation, the 5CuO catalyst has shown the highest selectivity of 85% while the 30CuO catalyst obtains the selectivity of 65% at the reaction temperature of 423 K.

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“…24 Polster et al relatam ainda que existem diferentes espécies de oxigênio da céria e do óxido de cobre que se reduzem a diferentes temperaturas no sólido CuO x -CeO 2 , mas estas são as mesmas espécies de oxigênio em cada óxido puro. 25 O perfil de RTP da titânia, mostrado na Figura 4, apresenta pequenas ondulações nas temperaturas de 500 e 600 ºC, não chegando a caracterizar um pico. Isto indica que, em toda a faixa experimental observada, a titânia não foi reduzida, resultados estes que coincidem com os relatados por Zhu et al 20 O perfil de RTP da céria/titânia, exibido na Figura 5, mostra um pico de redução a 858 ºC e três pequenos ombros a 368, 518 e 602 ºC.…”

Section: Redução a Temperatura Programadaunclassified

Estudo da reação de oxidação preferencial do co sobre o sistema CuO/CeO2-TiO2

Maciel

Assaf

2010

Quím. Nova

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Recebido em 24/2/10; aceito em 21/6/10; publicado na web em 17/9/10 CO PREFERENTIAL OXIDATION ON CuO/CeO 2 -TiO 2 SYSTEM. Cu catalysts supported on CeO 2 , TiO 2 and CeO 2 /TiO 2 were prepared by precipitation method and used for preferential oxidation of carbon monoxide contained in a hydrogen flow generated by methane steam reforming. The samples were characterized by XRD, BET and TPR techniques. The catalytic properties were studied in the 50-330ºC range by using a quartz micro-reactor vertically positioned on an electrical furnace. The results showed that the small copper particles generated with the lower metal content are the most easily reducible and give the best catalytic performance. In respect of support effect, the strong metal-support interaction and the redox characteristics of the CuO x -CeO 2 series resulted in the best catalytic results, especially with the sample with 1% copper content.Keywords: PROX-CO; copper; ceria. INTRODUÇÃOEstudos recentes relacionados com a tecnologia de células a combustível, especialmente aqueles envolvendo membranas poliméricas de troca iônica (PEMFC), têm estimulado o interesse pela reação de oxidação preferencial do monóxido de carbono (PROX-CO). Uma vez que as células PEMFC utilizam como fonte de energia o hidrogênio com elevada pureza, a reação de PROX-CO apresenta-se como um meio de purificar o hidrogênio produzido pelas reações de reforma do metano. 1-10O método convencional de produção de hidrogênio combina as reações de reforma a vapor do metano com a reação de deslocamento gás-água (WGS -water gas shift reaction), e os gases gerados apresentam a seguinte composição aproximada: 45% H 2 , 25% CO 2 , 10% H 2 O, 20% N 2 e 0,5-1% CO.1,2 Essa quantidade de CO presente no gás de reforma precisa ser removida devido a efeitos adversos que provoca no anodo das células PEMFC, ocasionando a desativação do eletrocatalisador de Pt que está depositado sobre uma camada difusora à base de carbono e teflon (PTFE). Assim, é necessária a remoção do CO, reduzindo seus níveis para valores menores que 10 ppm.1 Para alcançar esse nível de concentração, alguns caminhos são estudados: metanação catalítica, separação por membrana de Pd e oxidação preferencial do CO (PROX-CO).1,11 Destas, a PROX é a que oferece menor custo na redução dos níveis de CO sem o consumo excessivo de hidrogênio. 1Juntamente com a PROX-CO (Equação 1), a reação indesejada de oxidação do hidrogênio (Equação 2) pode ocorrer, diminuindo a eficiência do processo.(1)O catalisador convencional para a PROX-CO é Pt/g-Al 2 O 3 , porém diferentes tipos de catalisadores mostraram ser eficientes para a reação. Estes podem envolver fases ativas de metais nobres suportados, como platina e ouro, ou ainda metais não-nobres, como o cobre suportado em óxidos. 1,2Os catalisadores de metais nobres exibem boa atividade catalí-tica em temperaturas entre 150-250 ºC mas, além de apresentarem um alto custo, no geral, são pouco seletivos.3 Por outro lado, alguns catalisadores de metais não nobres suportados em óxidos têm se mostrado efic...

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Study of active sites and mechanism responsible for highly selective CO oxidation in H2 rich atmospheres on a mixed Cu and Ce oxide catalyst

Cited by 180 publications

References 25 publications

Characterization of Active Sites/Entities and Redox/Catalytic Correlations in Copper-Ceria-Based Catalysts for Preferential Oxidation of CO in H2-Rich Streams

Characterization of Active Sites/Entities and Redox/Catalytic Correlations in Copper-Ceria-Based Catalysts for Preferential Oxidation of CO in H2-Rich Streams

Effect of Cu Loading to Catalytic Selective CO Oxidation of CuO/CeO<sub>2</sub> –Co<sub>3</sub>O<sub>4</sub>

Estudo da reação de oxidação preferencial do co sobre o sistema CuO/CeO2-TiO2

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Study of active sites and mechanism responsible for highly selective CO oxidation in H2 rich atmospheres on a mixed Cu and Ce oxide catalyst

Cited by 180 publications

References 25 publications

Characterization of Active Sites/Entities and Redox/Catalytic Correlations in Copper-Ceria-Based Catalysts for Preferential Oxidation of CO in H2-Rich Streams

Characterization of Active Sites/Entities and Redox/Catalytic Correlations in Copper-Ceria-Based Catalysts for Preferential Oxidation of CO in H2-Rich Streams

Effect of Cu Loading to Catalytic Selective CO Oxidation of CuO/CeO&lt;sub&gt;2&lt;/sub&gt; –Co&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;

Estudo da reação de oxidação preferencial do co sobre o sistema CuO/CeO2-TiO2

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Effect of Cu Loading to Catalytic Selective CO Oxidation of CuO/CeO<sub>2</sub> –Co<sub>3</sub>O<sub>4</sub>