A microkinetic model of the methanol oxidation over silver

Andreasen, Anders; Lynggaard, H.; Stegelmann, Carsten; Stoltze, Per

doi:10.1016/j.susc.2003.08.007

Cited by 55 publications

(64 citation statements)

References 81 publications

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“…[48] For Ag at 400 °C in 0.1 mbar of pure oxygen (comparable to the partial pressure of oxygen in our experiments) the authors found a coverage of ~2% of O ads on Ag, i.e. just at the detection limit of XPS.…”

Section: Resultssupporting

confidence: 81%

Methanol Oxidation on a Copper Catalyst Investigated Using in Situ X-ray Photoelectron Spectroscopy

Bluhm¹,

Hävecker²,

et al. 2004

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The surface and near-surface region of an active catalyst and the adjacent gas-phase reactants were investigated simultaneously under reaction conditions using in situ X-ray photoelectron spectroscopy (XPS). This investigation of methanol oxidation on a copper catalyst showed that there was a linear correlation between the catalytic activity of the sample and the presence of a sub-surface oxygen species that can only be observed in situ. The concentration profile of the sub-surface oxygen species within the first few nanometers below the surface was determined using photon energy-dependent depth-profiling. The chemical composition of the surface and the near-surface region varied strongly with the oxygen-tomethanol ratio in the reactant stream. The experiments show that the pure metal is not an active catalyst for the methanol oxidation reaction, but that a certain amount of oxygen has to be present in the sub-surface region to activate the catalytic reaction. Oxide formation was found to be detrimental to formaldehyde production. Our results demonstrate also that for an understanding of heterogeneous catalysts a characterization of the surface alone may not be sufficient, and that sub-surface characterization is essential.

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Section: Resultssupporting

confidence: 81%

Methanol Oxidation on a Copper Catalyst Investigated Using in Situ X-ray Photoelectron Spectroscopy

Bluhm¹,

Hävecker²,

et al. 2004

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“…Kinetic models developed for studying methanol chemistry have mainly dealt with methanol synthesis over copper catalysts [21,22]. Recently, models of methanol oxidation over silver and palladium catalysts have also been published [23,24].…”

Section: Introductionmentioning

confidence: 99%

Prediction of Experimental Methanol Decomposition Rates on Platinum from First Principles

et al. 2006

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A microkinetic model for methanol decomposition on platinum is presented. The model incorporates competitive decomposition pathways, beginning with both O-H and C-H bond scission in methanol, and uses results from density functional theory (DFT) calculations [Greeley and Mavrikakis, J. Am. Chem. Soc. 124 (2002) 7193, Greeley and Mavrikakis, J. Am. Chem. Soc. 126 (2004) 3910].Results from reaction kinetics experiments show that the rate of H 2 production increases with increasing temperature and methanol concentration in the feed and is only nominally affected by the presence of CO or H 2 with methanol. The model, based on the values of binding energies, pre-exponential factors and activation energy barriers derived from first principles calculations, accurately predicts experimental reaction rates and orders. The model also gives insight into the most favorable reaction pathway, the rate-limiting step, the apparent activation energy, coverages, and the effects of pressure. It is found that the pathway beginning with the C-H bond scission (CH 3 OH fi H 2 COH fi HCOH fi CO) is dominant compared with the path beginning with O-H bond scission. The cleavage of the first C-H bond in methanol is the rate-controlling step. The surface is highly poisoned by CO, whereas COH appears to be a spectator species.

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“…Above 500 K, the yield of methyl formate increases linearly with temperature rising until about 573 K, and the yield of formaldehyde increases while temperature rising. The work of Nagy et al [18] shows that phase transformation region of Ag 2 O to Ag is between 503 K and 600 K. Raman spectroscopic study of Waterhouse et al [19] also shows that the ratio of O c /Ob reaches the maximum at about 573 K. With temperature rising, the stick time of a-oxygen species on catalysis decreases [24], so the ratio of O a /Oc decreases. The maximum yield of methyl formate was obtained at certain ratio of O a /O c .…”

Section: Discussionmentioning

confidence: 98%

Catalytic oxidation of methanol to methyl formate over silver ? a new purpose of a traditional catalysis system

Yang

2005

Catal Lett

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Catalytic reaction was performed in the unregarded temperature region over silver catalysts with long catalytic lifetime for the conversion of methanol to methyl formate. O a -saturated or O c -saturated silver catalysts were studied individually to identify the roles of O a , O c in the oxidative esterification of methanol over an unsupported polycrystalline silver catalyst. A synergic process is proposed based on the coexistence of a-oxygen species and c-oxygen species on the surface of polycrystalline silver at about 573 K.

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A microkinetic model of the methanol oxidation over silver

Cited by 55 publications

References 81 publications

Methanol Oxidation on a Copper Catalyst Investigated Using in Situ X-ray Photoelectron Spectroscopy

Methanol Oxidation on a Copper Catalyst Investigated Using in Situ X-ray Photoelectron Spectroscopy

Prediction of Experimental Methanol Decomposition Rates on Platinum from First Principles

Catalytic oxidation of methanol to methyl formate over silver ? a new purpose of a traditional catalysis system

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