Morphology effects of nanocrystalline CeO2 on the preferential CO oxidation in H2-rich gas over Au/CeO2 catalyst

Yi, Guangquan; Xu, Zhusheng; Guo, Guo‐Cong; Tanaka, Kenichi; Yuan, Youzhu

doi:10.1016/j.cplett.2009.08.011

Cited by 86 publications

(50 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The lowest activity of the Au/CeO 2 nanocubes was explained by the predominance of metallic gold species on the support surface and the negligible metal-support interaction, as demonstrated by X-ray photoelectron spectroscopy (XPS) and hydrogen-temperature programmed reduction (H 2 -TPR) [110]. Subsequently, Yuan and co-workers found that the activity in the preferential CO oxidation in H 2 -rich gas followed the same trend mentioned above [112,114]. Cao and co-workers demonstrated that the activity of Au/CeO 2 nanorods in CO oxidation was much higher than that of Au/CeO 2 nanoparticles [113].…”

Section: Effect Of the Particle Morphology Of The Supportmentioning

confidence: 72%

“…(2) can we find active gold catalysts based on previously overlooked supports (e.g., metal phosphates)? In addition, the effects of the crystal phase [65,82,[96][97][98][99][100], size [99,[101][102][103][104][105][106][107][108], and shape [45,[108][109][110][111][112][113][114] of solid supports on the catalytic performance are also of interest. Below we first present the development of Au/SiO 2 and Au/metal phosphate catalysts in our group, and then highlight recent findings on the effects of the particle size and shape of solid supports.…”

Section: General Considerationsmentioning

confidence: 99%

See 1 more Smart Citation

Development of novel supported gold catalysts: A materials perspective

2010

View full text Add to dashboard Cite

Since Haruta et al. discovered that small gold nanoparticles finely dispersed on certain metal oxide supports can exhibit surprisingly high activity in CO oxidation below room temperature, heterogeneous catalysis by supported gold nanoparticles has attracted tremendous attention. The majority of publications deal with the preparation and characterization of conventional gold catalysts (e.g., Au/TiO 2 ), the use of gold catalysts in various catalytic reactions, as well as elucidation of the nature of the active sites and reaction mechanisms. In this overview, we highlight the development of novel supported gold catalysts from a materials perspective. Examples, mostly from those reported by our group, are given concerning the development of simple gold catalysts with single metal-support interfaces and heterostructured gold catalysts with complicated interfacial structures. Catalysts in the first category include active Au/SiO 2 and Au/metal phosphate catalysts, and those in the second category include catalysts prepared by pre-modification of supports before loading gold, by post-modification of supported gold catalysts, or by simultaneous dispersion of gold and an inorganic component onto a support. CO oxidation has generally been employed as a probe reaction to screen the activities of these catalysts. These novel gold catalysts not only provide possibilities for applied catalysis, but also furnish grounds for fundamental research.

show abstract

Section: Effect Of the Particle Morphology Of The Supportmentioning

confidence: 72%

Section: General Considerationsmentioning

confidence: 99%

Development of novel supported gold catalysts: A materials perspective

2010

View full text Add to dashboard Cite

show abstract

“…Several authors [25][26][27][28] have used nanostructured ceria that expose certain planes to investigate the influence of the nature of the ceria surface on the nature and activity of gold species. By judicious choice of the hydrothermal treatment conditions of hydrolyzed cerium(III) salts, singlecrystalline nanopolyhedra, nanorods and nanocubes were obtained [29,30].…”

Section: Introductionmentioning

confidence: 99%

Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

et al. 2011

View full text Add to dashboard Cite

The interaction of gold atoms with CeO 2 nanocrystals having rod and cube shapes has been examined by cyanide leaching, TEM, TPR, CO IR and X-ray absorption spectroscopy. After deposition-precipitation and calcination of gold, these surfaces contain gold nanoparticles in the range 2-6 nm. For the ceria nanorods, a substantial amount of gold is present as cations that replace Ce ions in the surface as follows from their first and second coordination shells of oxygen and cerium by EXAFS analysis. These cations are stable against cyanide leaching in contrast to gold nanoparticles. Upon reduction the isolated Au atoms form finely dispersed metal clusters with a high activity in CO oxidation, the WGS reaction and 1,3-butadiene hydrogenation. By analogy with the very low activity of reduced gold nanoparticles on ceria nanocubes exposing the {100} surface plane, it is inferred that the gold nanoparticles on the ceria nanorod surface also have a low activity in such reactions. Although the finely dispersed Au clusters are thermally stable up to quite high temperature in line with earlier findings (Y. Guan and E. J. M. Hensen, Phys Chem Chem Phys 11:9578, 2009), the presence of gold nanoparticles results in their more facile agglomeration, especially in the presence of water (e.g., WGS conditions). For liquid phase alcohol oxidation, metallic gold nanoparticles are the active sites. In the absence of a base, the O-H bond cleavage appears to be rate limiting, while this shifts to C-H bond activation after addition of NaOH. In the latter case, the gold nanoparticles on the surface of ceria nanocubes are much more active than those on the surface of nanorod ceria.

show abstract

“…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][2][3][4][5][6][7][8][9][10] O 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.…”

Section: Introductionunclassified

“…Nos últimos anos, a céria tem sido muito estudada como suporte em catálise, além de ser um poderoso promotor que modifica propriedades estruturais e eletrônicas de muitos catalisadores usados em importantes reações industriais, tais como, a quebra de óleos pesados em zeólitas, a conversão automotiva, a reforma a vapor e seca do metano e a reação de deslocamento gás-água. [3][4][5][6][7][8][9][10]12 O uso da céria como promotor está normalmente relacionado à sua capacidade de armazenar oxigênio e a aspectos estruturais, como a propriedade de aumentar a dispersão dos metais. Na presença de um metal de transição, o tamanho pequeno do cristal de céria favorece a formação de espécies de oxigênio altamente reativas.…”

unclassified

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

Maciel

Assaf

2010

Quím. Nova

View full text Add to dashboard Cite

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...

show abstract

Morphology effects of nanocrystalline CeO2 on the preferential CO oxidation in H2-rich gas over Au/CeO2 catalyst

Cited by 86 publications

References 31 publications

Development of novel supported gold catalysts: A materials perspective

Development of novel supported gold catalysts: A materials perspective

Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

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

Contact Info

Product

Resources

About