Interaction between Pd and Ag on the surface of silica

Karski, S.; Witońska, Izabela; Rogowski, Jacek; Gołuchowska, J.

doi:10.1016/j.molcata.2005.06.053

Cited by 20 publications

(24 citation statements)

References 31 publications

(21 reference statements)

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“…Reduction pretreatment caused a blue shift of the absorption bands and a diminution of the deviation from linearity suggesting more homogeneous AgAu alloy structures. This effect could be explained by the following: oxygen treatment favors the Ag concentration enhancement on the surface because Ag-oxide formation is thermodynamically favored, but as the temperature raises the decomposition of the preformed oxide is occurred above 250°C [56]. Modification of the surface plasmon of the particles likely reflects this surface structure/geometry change, that can be an important factor affecting the catalytic properties.…”

Section: Structure Of the Agau/sio 2 Catalystsmentioning

confidence: 99%

Bimetallic Ag–Au/SiO2 catalysts: Formation, structure and synergistic activity in glucose oxidation

Benkó

Beck

Frey

et al. 2014

Applied Catalysis A: General

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SiO 2 supported Ag-Au bimetallic catalysts were prepared by sol adsorption method with 10/90, 20/80, 33/67, and 50/50 Ag/Au molar ratios. Reduction of HAuCl 4 in Ag sol resulted in alloyed AgAu colloid particles and that structure remained after calcination and reduction treatment. The alloy structure of the catalysts was confirmed by UV-visible spectroscopy and high resolution transmission electron microscopy. The Au-Ag bimetallic effect and its dependence on the Ag/Au molar ratio was studied in glucose oxidation where synergistic activity increase was observed compared to the Au/SiO 2 reference sample in case of the bimetallic samples with less than Ag/Au=50/50 molar ratio. The Ag/SiO 2 was inactive at the same conditions. The Ag/Au surface atomic ratios -calculated by X-ray photoelectron spectroscopy (XPS) -were slightly higher than in the bulk -determined by prompt gamma activation analysis (PGAA). The higher activity of the bimetallic samples is suggested to be caused by the improved O 2 activating ability provided by Ag sites. The further increase of Ag loading above the optimal concentration may dilute or cover the Au to such an extent that the number of gold ensembles necessary for glucose activation decreases deteriorating the activity.

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Section: Structure Of the Agau/sio 2 Catalystsmentioning

confidence: 99%

Bimetallic Ag–Au/SiO2 catalysts: Formation, structure and synergistic activity in glucose oxidation

Benkó

Beck

Frey

et al. 2014

Applied Catalysis A: General

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“…The monometallic catalysts which were studied thoroughly are palladium systems supported on Al 2 O 3 [1,2], C [3][4][5], SnO 2 [6][7][8], CeO 2 [9], TiO 2 [10,11], and pumice [12]. Monometallic palladium catalysts are not very active in the reaction of nitrate reduction.…”

Section: Introductionmentioning

confidence: 99%

The effect of support porosity on the selectivity of Pd–In/support catalysts in nitrate reduction

Krawczyk

Karski

Witońska

2011

Reac Kinet Mech Cat

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The influence of support porosity on the selectivity of home-made 5%Pd-2%In/support (support = SiO 2 , Al 2 O 3 , TiO 2 ) catalysts in nitrate reduction was studied. The main final products of the reaction were N 2 and NH 4? . Together with the decrease in pore diameter, an increase in ammonia concentration in the reaction mixture was observed. It is probably caused by slow diffusion of OH -ions from narrow pores to the solution.

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“…However, monometallic palladium catalysts (Pd/support) are active only in the reduction of nitrates(III). Some researchers explain the low activity of Pd/support catalysts in comparison with bimetallic Pd-M/support systems in the reduction of nitrates(V) by different mechanisms of these processes such as a redox, and a catalytic mechanisms [3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Temperature-programmed desoprtion of H2 from the surfaces of pd/support and Pd-Ag/support catalysts (support = Al2O3, SiO2)

Witońska

Karski

Frajtak

et al. 2008

React Kinet Catal Lett

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Thermal desorption of H 2 from the surface of Pd/support and Pd-Ag/support (support = Al 2 O 3 , SiO 2 ) catalysts has been investigated. Two wide desorption peaks can be observed for the 5%Pd/support catalyst. The presence of these peaks in the thermogram indicates that several adsorption states exist, which is the result of occurrance of different adsorption centers of specific bond strengths for hydrogen. The addition of silver to the palladium catalysts causes a considerable decrease in the size of the high temperature desorption peak. It is also worth noting that the temperature of the maximum of the desorption rate remains practically constant for all bimetallic catalysts studied. This means that the activation energy of the hydrogen desorption process does not change after the introduction of silver to the palladium catalyst.

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Interaction between Pd and Ag on the surface of silica

Cited by 20 publications

References 31 publications

Bimetallic Ag–Au/SiO2 catalysts: Formation, structure and synergistic activity in glucose oxidation

Bimetallic Ag–Au/SiO2 catalysts: Formation, structure and synergistic activity in glucose oxidation

The effect of support porosity on the selectivity of Pd–In/support catalysts in nitrate reduction

Temperature-programmed desoprtion of H2 from the surfaces of pd/support and Pd-Ag/support catalysts (support = Al2O3, SiO2)

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