Gold/hydroxyapatite catalystsSynthesis, characterization and catalytic activity to CO oxidation

Domínguez, M.I.; Romero-Sarria, Francisca; Centeno, M.A.; Odriozola, J.A.

doi:10.1016/j.apcatb.2008.09.016

Cited by 99 publications

(73 citation statements)

References 39 publications

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“…However, metal salts have been seldom used as supports for making gold catalysts [73,[133][134][135][136][137][138][139][140][141][142][143][144]. This is so, not only because the bulk of gold catalysis papers have been following the classic work of Haruta and co-workers who used metal oxide supports [15][16][17], but also because compared with metal salts, metal oxides are more frequently encountered in heterogeneous catalysis.…”

Section: Au/metal Phosphatesmentioning

confidence: 97%

Development of novel supported gold catalysts: A materials perspective

2010

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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.

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Section: Au/metal Phosphatesmentioning

confidence: 97%

Development of novel supported gold catalysts: A materials perspective

2010

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“…The presence of the cationic species of gold was confirmed by means of XPS measurements, and the presence of superoxide and peroxide species on ceria throughout Raman spectroscopy. The formation of peroxide species upon oxygen adsorption on electron-rich support vacancies has also been proposed for other Au catalysts [21].…”

Section: Characterization Of Au/ceo 2 Catalysts Involved In Oxidationmentioning

confidence: 99%

“…Currently, gold supported on a reducible transition metal oxide always exhibits better activity for CO oxidation than gold supported on non-reducible oxides [6,158]. However, non-reducible materials with electron-rich oxygen vacancies may also enhance the catalytic activity of gold by activating gaseous oxygen [16,21]. Ceria, due to its chemical properties, has become one of the most promising supports for oxidation reactions and has been broadly studied [7][8][9][10]15,17,20,26,28,51,57,129,143,[159][160][161].…”

Section: Co Oxidationmentioning

confidence: 99%

Au/CeO2 Catalysts: Structure and CO Oxidation Activity

et al. 2016

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Abstract:In this comprehensive review, the main aspects of using Au/CeO 2 catalysts in oxidation reactions are considered. The influence of the preparation methods and synthetic parameters, as well as the characteristics of the ceria support (presence of doping cations, oxygen vacancies concentration, surface area, redox properties, etc.) in the dispersion and chemical state of gold are revised. The proposed review provides a detailed analysis of the literature data concerning the state of the art and the applications of gold-ceria systems in oxidation reactions.

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“…Studies of this reaction using an inert support (calcium hydroxyapatite) evidenced that the creation of structural oxygen vacancies by removal of hydroxyl/carbonate groups from the support structure increases the CO conversion rate. 30 In this case, the interaction of gaseous O 2 with the oxygen vacancies created in the support, generates peroxide species that are responsible for the high CO conversion detected at room temperature.…”

Section: -9mentioning

confidence: 99%

Surface oxygen vacancies in gold based catalysts for CO oxidation

et al. 2014

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Experimental catalytic activity measurements, diffuse reflectance infrared Fourier spectroscopy, and density functional theory calculations are used to investigate the role and dynamics of surface oxygen vacancies in CO oxidation with O 2 catalyzed by Au nanoparticles supported on a Y-doped TiO 2 catalyst. Catalytic activity measurements show that the CO conversion is improved in a second cycle of reaction if the reactive flow is composed by CO and O 2 (and inert) while if water is present in the flow, the catalyst shows a similar behaviour in two successive cycles. DRIFTS-MS studies indicate the occurrence of two simultaneous phenomena during the first cycle in dry conditions: the surface is dehydroxylated and a band at 2194 cm À1 increases (proportionally to the number of surface oxygen vacancies). Theoretical calculations were conducted in order to explain these observations. On one hand, the calculations show that there is a competition between gold nanoparticles and OH to occupy the surface oxygen vacancies and that the adsorption energy of gold on these sites increases as the surface is being dehydroxylated. On the other hand, these results evidence that a strong electronic transfer from the surface to the O 2 molecule is produced after its adsorption on the Au/TiO 2 perimeter interface (activation step), leaving the gold particle in a high oxidation state. This explains the appearance of a band at a wavenumber unusually high for the CO adsorbed on oxidized gold particles (2194 cm À1 ) when O 2 is present in the reactive flow.These simultaneous phenomena indicate that a gold redispersion on the surface occurs under reactive flow in dry conditions generating small gold particles which are very active at low temperature. This fact is notably favoured by the presence of surface oxygen vacancies that improve the surface dynamics. The obtained results suggest that the reaction mechanism proceeds through the formation of a peroxo-like complex formed after the electronic transfer from the surface to the gas molecule.

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Gold/hydroxyapatite catalystsSynthesis, characterization and catalytic activity to CO oxidation

Cited by 99 publications

References 39 publications

Development of novel supported gold catalysts: A materials perspective

Development of novel supported gold catalysts: A materials perspective

Au/CeO2 Catalysts: Structure and CO Oxidation Activity

Surface oxygen vacancies in gold based catalysts for CO oxidation

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