Microkinetic analysis of the oxygen–silver system

Stegelmann, Carsten; Stoltze, Per

doi:10.1016/j.susc.2004.01.028

Cited by 18 publications

(10 citation statements)

References 47 publications

(115 reference statements)

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“…In general, many statements of the microkinetic model developed in Stegelman's papers [14,15,49] are in good agreement with the data obtained in the present paper which can serve as experimental basis of the model. The main idea of the model is that epoxidation and combustion go through common intermediate (oxametallacycle) as suggested by Campbell et al [1,2] and Barteau [11,12].…”

Section: Discussionsupporting

confidence: 90%

“…The main discrepancy between the present work and the microkinetic model developed in [14,15,49] is an interrelation between electrophilic and nucleophilic oxygen. Stegelman et al have proposed that electrophilic oxygen adsorbs on the surface oxide, in that way competing with ethylene for the surface sites.…”

Section: Discussioncontrasting

confidence: 88%

“…Stegelmann et al [14] have concluded that ethylene can adsorb both on surface oxide and on metallic silver. However, they also have shown that the contribution of the latter route of ethylene adsorption is much less important in mbar pressure range than the route in the presence of surface oxide [15].…”

Section: Discussionmentioning

confidence: 99%

“…Both oxametallacycle [11,12] and π-bonded ethylene [3,8,13] are discussed in the literature, but on the basis of the currently available data it is difficult to determine which species (or both) is indeed the intermediate in the epoxidation route. Recent microkinetic modeling investigations [14,15] allowed the elucidation of some aspects of the reaction mechanism. However, experimental studies under in-situ conditions, which will provide a direct correlation between the catalytic activity and the surface composition, have not been performed so far.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Combined in situ XPS and PTRMS study of ethylene epoxidation over silver

Bukhtiyarov

Nizovskiĭ

Bluhm

et al. 2006

Journal of Catalysis

131

129

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Ethylene epoxidation over silver was investigated by combined in-situ X-ray photoelectron spectroscopy (XPS) and proton-transfer reaction mass-spectrometry (PTRMS) at temperatures from 300 to 520 K and in the pressure range from 0.07 to 1 mbar. Ethylene oxide was present among the reaction products at T ≥ 420 K and P ≥ 0.3 mbar. The catalytically active surface contains two oxygen species -nucleophilic and electrophilic oxygen. The observed correlation between the abundance of electrophilic oxygen and the yield of ethylene oxide expressed as C 2 H 4 O partial pressure indicates that namely this oxygen species oxidizes ethylene to ethylene oxide. Opposite trend is observed for nucleophilic oxygen: the higher is the abundance of this species, the lower is the yield of ethylene oxide. This result is in line with the known fact that nucleophilic oxygen due to its oxidic nature is active in total oxidation of ethylene to CO 2 and H 2 O. The low activity of silver at T < 420 K is caused by the presence of carbonates and carbonaceous residues at the silver surface that reduce the available silver surface area for the catalytic reaction. Reduction of the surface area available for the formation of active species due to accumulation of the embedded oxygen species explains also the decrease of the rate of ethylene oxide formation with time observed for T ≥ 470 K.

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Section: Discussionsupporting

confidence: 90%

Section: Discussioncontrasting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Combined in situ XPS and PTRMS study of ethylene epoxidation over silver

Bukhtiyarov

Nizovskiĭ

Bluhm

et al. 2006

Journal of Catalysis

131

129

View full text Add to dashboard Cite

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“…in the partial oxidation of methanol to formaldehyde [247] and in the increased reaction probability for selective CO oxidation in presence of H 2 [248]. The active role of subsurface and/or of dissolved oxygen in ethylene epoxide production has recently been questioned [249][250][251], but the contrasting literature on this topic [252][253][254][255] demonstrates that the issue is highly controversial.…”

Section: Oxygen Interaction With Stepped Ag Surfacesmentioning

confidence: 99%

Bridging the structure gap: Chemistry of nanostructured surfaces at well-defined defects

Vattuone

Savio

Rocca

2008

Surface Science Reports

121

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Theoretical Modelling of Catalytic Reactions

Stoltze

Nørskov

2008

Handbook of Heterogeneous Catalysis

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A catalyst is a substance which modifies the rate or the selectivity of a chemical reaction. A particular catalyst and reaction system is therefore characterized by the rates for different elementary steps in the reaction, and the theoretical modelling of catalytic reactions must therefore, as the end product, have the calculation of the kinetics.The kinetics of a catalytic reaction is usually measured in a reactor under conditions relevant to the industrial process. The measured overall rate can then be fitted to a mathematical model, the macroscopic kinetics. This is extremely convenient for process design purposes [1,2].If the aim is to explore the mechanism of the reaction and to understand which are the important parameters of the catalyst determining the activity, then a microkinetic model is needed. A microkinetic model is based on a detailed mechanism and independent information about the rates of the elementary steps involved and the stability of intermediates. It can be said that the microkinetic model is the synthesis of all the basic knowledge about a reaction over a given catalyst.The input into a microkinetic model is usually measured or calculated as the stability of intermediates, measured or calculated rates of elementary steps together with thermodynamic data for the gas (or liquid) phase above the catalyst.

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Microkinetic analysis of the oxygen–silver system

Cited by 18 publications

References 47 publications

Combined in situ XPS and PTRMS study of ethylene epoxidation over silver

Combined in situ XPS and PTRMS study of ethylene epoxidation over silver

Bridging the structure gap: Chemistry of nanostructured surfaces at well-defined defects

Theoretical Modelling of Catalytic Reactions

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