Low-temperature activity of Au/CeO2 for water gas shift reaction, and characterization by ADF-STEM, temperature-programmed reaction, and pulse reaction

Sakurai, Hiroaki; Akita, Tomoki; Tsubota, Susumu; Kiuchi, Masato; Haruta, Masatake

doi:10.1016/j.apcata.2005.02.043

Cited by 178 publications

(111 citation statements)

References 26 publications

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“…However, the presence of platinum nanoparticles was confirmed by EDS analysis. A similar observation was described in the literature for gold catalysts [26,27]. Small gold particles supported on ceria could not be detected by TEM due to the small contrast between the metal particle and the support.…”

Section: Catalyst Characterizationsupporting

confidence: 87%

Influence of the metal precursor on the catalytic behavior of Pt/Ceria catalysts in the preferential oxidation of CO in the presence of H2 (PROX)

Jardim

Rico-Francés

Coloma

et al. 2015

Journal of Colloid and Interface Science

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The effect of the metal precursor (presence or absence of chlorine) on the preferential oxidation of CO in the presence of H2 over Pt/CeO2 catalysts has been studied. The catalysts were prepared using (Pt(NH3)4)(NO3)2 and H2PtCl6, as precursors, in order to ascertain the effect of the chlorine species on the chemical properties of the support and on the catalytic behavior of these systems in the PROX reaction. The results show that chloride species exert an important effect on the redox properties of the oxide support due to surface chlorination. Consequently, the chlorinated catalyst exhibits a poorer catalytic activity at low temperatures compared with the chlorine-free catalyst, and this is accompanied by a higher selectivity to CO2 even at high reaction temperatures. It is proposed that the CO oxidation mechanism follows different pathways on each catalyst. This is a previous version of the article published in Journal of Colloid and Interface Science. 2015, 443: 45-55. doi:10.1016/j.jcis.2014 3: Graphical Abstract (for review)• The presence or absence of Cl in the Pt precursor strongly affects the catalytic behavior.• The Pt precursor affects the PROX mechanism at low reaction temperatures.• At 333 K, the mechanism in the Cl-free catalyst seems to involve the -OH groups on the support.• At higher temperatures, the reaction occurs via the same mechanism on both catalysts.. Highlights (for review) AbstractThe effect of the metal precursor (presence or absence of chlorine) on the preferential oxidation of CO in the presence of H 2 over Pt/CeO 2 catalysts has been studied. The catalysts are prepared using (Pt(NH 3 ) 4 )(NO 3 ) 2 and H 2 PtCl 6 , as precursors, in order to ascertain the effect of the chlorine species on the chemical properties of the support and on the catalytic behavior of these systems in the PROX reaction. The results show that chloride species exert an important effect on the redox properties of the oxide support due to surface chlorination. Consequently, the chlorinated catalyst exhibits a poorer catalytic activity at low temperatures compared with the chlorine-free catalyst, and this is accompanied by a higher selectivity to CO 2 even at high reaction temperatures. It is proposed that the CO oxidation mechanism follows different pathways on each catalyst.

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Section: Catalyst Characterizationsupporting

confidence: 87%

Influence of the metal precursor on the catalytic behavior of Pt/Ceria catalysts in the preferential oxidation of CO in the presence of H2 (PROX)

Jardim

Rico-Francés

Coloma

et al. 2015

Journal of Colloid and Interface Science

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“…A third type of explanation involves the support directly. This includes transfer of activated oxygen from the support (i.e., reducible or irreducible support), or special active sites at the metal/oxide boundary [8,[54][55][56][57][58][59][60][61][62][63][64]. Finally, there are a number of reports of catalysts consisting of single or a few Au + ions in the support [27,[65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81].…”

Section: Introductionmentioning

confidence: 99%

Insights into the reactivity of supported Au nanoparticles: combining theory and experiments

et al. 2007

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The origin of the extraordinary catalytic activity of gold nanoparticles is discussed on the basis of density-functional calculations, adsorption studies on single crystal surfaces, and activity measurements on well characterized supported gold particles. A number of factors are identified contributing to the activity, and it is suggested that it is useful to consider lowcoordinated Au atoms as the active sites, for example, CO oxidation and that the effect of the support can be viewed as structural and electronic promotion. We identify the adsorption energy of oxygen and the Au-support interface energy as important parameters determining the catalytic activity.

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“…Also, the strength of interaction between the gold particle and the support may play a significant role in determining the stability of these systems at higher pressures. 4 For example, Valden et al [22] observed by scanning tunneling microscopy (STM) ex situ a form of Ostwald ripening (the growth of large particles at the expense of small particles) by exposing the Au/TiO 2 (110) surface to 10 Torr of O 2 for 2 hours at room temperature. This effect was found to be stronger in a CO + O 2 (2:1) mixture.…”

Section: Introductionmentioning

confidence: 99%

“…The nature of the active species in highly dispersed Au catalysts (ionic vs metallic, low-coordinated surface atoms vs metal/support interface) is a matter of extensive debates. Among many gold catalysts reported in the literature, those supported on the cerium oxide (CeO 2 ) often show a superior activity ( [2][3][4][5][6][7][8][9], and references therein). It should be mentioned that the reaction mechanisms, involving cationic Au 3+ and Au + species as the most active, have been reinforced after experimental observations by Flutzani-Staphanopolus and co-workers on the Au/CeO 2 catalysts [10].…”

Section: Introductionmentioning

confidence: 99%

Gold supported on well-ordered ceria films: nucleation, growth and morphology in CO oxidation reaction

et al. 2007

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Abstract. Structure of gold nanoparticles formed by physical vapor deposition onto thin ceria films was studied by scanning tunneling microscopy (STM). Gold preferentially nucleates on point defects present on the terraces of the well-ordered, fully oxidized films to a low density. The nucleation expands to the terrace step edges, providing a large variety of low-coordinated sites. Only at high coverage, the Au particles grow homogeneously on the oxygen-terminated CeO 2 (111) terraces. The morphology of Au particles was further examined by STM in situ and ex situ at elevated (up to 20 mbar) pressures of O 2 , CO, and CO + O 2 at 300 K. The particles are found to be stable in O 2 ambient up to 10 mbar, meanwhile gold sintering emerges at CO pressures above ~ 1 mbar. Sintering of the Au particles, which mainly proceeds along the step edges of the CeO 2 (111) support, is observed in CO + O 2 (1:1) mixture at much lower pressure (~10 -3 mbar), thus indicating that the structural stability of the Au/ceria catalysts is intimately connected with its reactivity in the CO oxidation reaction.

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Low-temperature activity of Au/CeO2 for water gas shift reaction, and characterization by ADF-STEM, temperature-programmed reaction, and pulse reaction

Cited by 178 publications

References 26 publications

Influence of the metal precursor on the catalytic behavior of Pt/Ceria catalysts in the preferential oxidation of CO in the presence of H2 (PROX)

Influence of the metal precursor on the catalytic behavior of Pt/Ceria catalysts in the preferential oxidation of CO in the presence of H2 (PROX)

Insights into the reactivity of supported Au nanoparticles: combining theory and experiments

Gold supported on well-ordered ceria films: nucleation, growth and morphology in CO oxidation reaction

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