Structure Sensitive Hydrogen Adsorption: Effect of Ag on Ru/SiO2Catalysts

Savargaonkar, N.; Narayan, R.L.; Pruski, Marek; Üner, Deniz; King, T.S.

doi:10.1006/jcat.1998.2115

Cited by 19 publications

(15 citation statements)

References 23 publications

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“…The angle of incidence is fxed at 45 O , measured from the macroscopic surface normal. Rate constants for hydrogen adsorption on RulSiOa catalyst at 296 K (Savargaonkar and King, 1998) The apparent rate constants for hydrogen adsorption and desorption were obtained (Savargaonkar and King, 1998) assuming that the adsorption process was Langmuirian with one type of adsorption sites. The rate constants, themselves, were estimated from selective excitation NMR experiments using the model of Engelke et al (1994).…”

Section: Modeling Of Spillover On the Supportmentioning

confidence: 99%

“…The desorption rate constant will be a strong function of temperature as it is an activated process. The activation barrier can be assumed to be about 90 kJ/mol from the microcalorimetry data (Narayan, 1998). The preexponential factors, as before, can be assumed to remain constant when the temperature is increased to 400 K from 296 K.…”

Section: Modeling Of Spillover On the Supportmentioning

confidence: 99%

“…The dynamics and energetics of hydrogen chemisorption on silica supported ruthenium and ruthenium-silver bimetallic catalysts have also been investigated by 1H NMR spectroscopy and microcalorimetry (Savargaonkar et al, 1998). The amount of hydrogen adsorbed on Ru particles was drastically reduced with addition of silver.…”

Section: Chapter 1 General Introductionmentioning

confidence: 99%

“…Hydrogen adsorption on the surface of Ru-Ag bimetallics supported on Si02 have been found to be a structure sensitive process (Savargaonkar et al, 1998). One of the hydrocarbon reactions which has been found to be strongly structure sensitive is hydrogenolysis.…”

Section: Chapter 1 General Introductionmentioning

confidence: 99%

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Structure sensitive adsorption of hydrogen on ruthenium and ruthenium-silver catalysts supported on silica

Kumar

1999

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Section: Modeling Of Spillover On the Supportmentioning

confidence: 99%

Section: Modeling Of Spillover On the Supportmentioning

confidence: 99%

Section: Chapter 1 General Introductionmentioning

confidence: 99%

Section: Chapter 1 General Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Structure sensitive adsorption of hydrogen on ruthenium and ruthenium-silver catalysts supported on silica

Kumar

1999

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“…One type of bimetallic clusters investigated extensively is a combination of a group VIII and a group IB metals. The bimetallic catalysts of Ru-Cu, Ru-Ag, Ru-Zn, and Ru-Au are examples of this type of catalysts where one of elements (Ru) is catalytically active and the second metal (Cu, Ag, Zn, or Au) is relatively inactive [2][3][4][5][6][7][8]. For Ru-Au/SiO 2 catalysts, it was reported that Ru and Au did not exist as separate particles, but formed bimetallic aggregates with a surface composition similar to that in the bulk phase.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Oxygenated Volatile Organic Compound Over Monometallic and Bimetallic Ru–Au Catalysts

et al. 2010

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Temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) of methanol and oxygen were used to probe the surface properties, relating to the oxidation reaction of methanol (a representative of oxygenated volatile organic compounds) over a series of monometallic and bimetallic Ru-Au catalysts. The relative amounts of ruthenium and gold in these bimetallic catalysts were found to strongly affect their surface characteristics (TPR and TPD profiles, BET surface areas, surface morphologies observed in SEM micrographs, and XRD patterns) and methanol oxidation activity. Although ruthenium and gold were immiscible in their bulk state, the TPR profiles, SEM micrographs, and XRD patterns provided evidence for the interactions between ruthenium and gold in the bimetallic catalysts, especially the 3.32 wt% Ru-0.61 wt% Au/SiO 2 exhibiting the highest methanol oxidation activity. After the oxidation reaction, even though Ru was oxidized to RuO 2 , the interaction between ruthenium and gold on silica still remained the same. The support material was also found to affect both the catalyst characteristics and the methanol oxidation activity. No bimetallic clusters were observed on the Ru-Au catalysts supported on alumina. Various products, including CO 2 , were found when using the catalysts supported on alumina, causing a higher methanol conversion than the catalysts supported on silica.

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A Kinetic Study on the Adsorption and Reaction of Hydrogen over Silica-Supported Ruthenium and Silver–Ruthenium Catalysts during the Hydrogenation of Carbon Monoxide

VanderWiel

Pruski

King

1999

Journal of Catalysis

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kinetic study on the adsorption and reaction of hydrogen over silica-supported ruthenium and silverruthenium catalysts during the hydrogenation of carbon monoxide " (1998) Table 2. Summar\' of kinetic parameters for CO hydrogenation over Ru/SiO; 40 Table 3. Summar\-of kinetic parameters for CO hydrogenation over Ag-Ru/Si02 50 Table 4. Comparison of kinetic parameters for methanation over supported Ru 55 Table 5. Rate decreases during CO hydrogenation upon addition of Ag to Ru 57 catalysts Table 6. Experimental design 83 Table 7. Statistical analysis of Ru/Si02 rate data 85 Table 8. Statistical analysis of Ag-Ru/SiO^ rate data 86. RESEARCH OBJECTIVESAlthough the cataKtic hydrogenation of carbon monoxide has been a subject of considerable investigation for many years, its increasing economical attractiveness as an industrial source of hydrocarbons has recently led to a search for more active and selectiv e catalysts. A fundamental problem in the development of such catalysts is an incomplete knowledge of the operative surface processes, due in large part to the inability to accurately measure surface concentrations of reactant species during reaction. Specifically, the concentration of surface hydrogen proves difficult to estimate using normally revealing techniques such as transient isotopic e.xchange due to kinetic isotope effects. Knowledge of such concentrations is essential to the determination of the mechanisms of adsorption and reaction, since many kinetic parameters are concentration dependent.It is the aim of this research to investigate the mechanism and kinetics of the adsorption and reaction of hydrogen on silica-supported ruthenium and silver-ruthenium catalysts during the hydrogenation of carbon monoxide. The specific activity of ruthenium in Group IB-ruthenium bimetallic catalysts is known to decrease dramaticalh' upon addition of the Group IB metal, even though these metals do not directly adsorb or react with hydrogen or carbon monoxide. Since silver is known to selectively occupy low-coordination sites in silver-ruthenium bimetallic systems, it can be used as a tool to block these sites from adsorption and reaction. In this way. any differences between the kinetics of processes occurring at these sites can be resolved. The mechanism of this synergistic effect will be elucidated in terms of a "portal site mediated adsorption" model. Previous work by our group has proposed that hydrogen adsorption occurs via a mechanism where lowcoordination "portal" sites on the catalyst serve as locations for rapid, dissociative adsorption of hydrogen to supply the surface with hydrogen for reaction with carbon monoxide.By preadsorbing carbon monoxide onto the surface of ruthenium and silver-ruthenium catalysts, the kinetics of hydrogen adsorption and reaction can be monitored upon exposure of this surface to ambient hydrogen gas. This is accomplished by conducting identical experiments on two separate systems. First, the formation of methane is monitored using mass spectroscopy, and specific reaction rates a...

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Structure Sensitive Hydrogen Adsorption: Effect of Ag on Ru/SiO2Catalysts

Cited by 19 publications

References 23 publications

Structure sensitive adsorption of hydrogen on ruthenium and ruthenium-silver catalysts supported on silica

Structure sensitive adsorption of hydrogen on ruthenium and ruthenium-silver catalysts supported on silica

Oxidation of Oxygenated Volatile Organic Compound Over Monometallic and Bimetallic Ru–Au Catalysts

A Kinetic Study on the Adsorption and Reaction of Hydrogen over Silica-Supported Ruthenium and Silver–Ruthenium Catalysts during the Hydrogenation of Carbon Monoxide

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