Acetic acid adsorption and decomposition on Pd(110)

Bowker, Michael; Morgan, Chris; Couves, J. W.

doi:10.1016/j.susc.2003.12.040

Cited by 75 publications

(92 citation statements)

References 43 publications

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“…The intensities for each component as a function of annealing temperature are plotted in figure 6b, After a flash to 380 K the intensity of the carbon features at 284.3 and 288.5 eV decreases rapidly. This reduction in intensity is likely due to desorption of ethylene and acetate species, in agreement with previous studies [26][27][28], showing desorption of acetate species at approximately 350 K. Flashing to much higher temperatures, i.e., >500 K, removes adsorbed CO (at 285.5 eV), and at still higher temperatures, the feature at 284.2 eV, assigned to amorphous carbon and CH x species, disappears. Note that during this transformation no apparent change was observed in the binding energy of the Pd 3d feature.…”

Section: Xpssupporting

confidence: 92%

“…Madix et al [25], have reported that the saturation coverage for CO on Pd(100) at room temperature is 0.53 ML. By comparing the peak area of the C 1s is [19] and acetic acid [26] to be approximately 1.5 ML. These authors report that of this 1.5, 0.5 ML is on the topmost surface while the remainder is interdiffused into the top several layers of the catalyst [18,19,26].…”

Section: Xpsmentioning

confidence: 99%

“…By comparing the peak area of the C 1s is [19] and acetic acid [26] to be approximately 1.5 ML. These authors report that of this 1.5, 0.5 ML is on the topmost surface while the remainder is interdiffused into the top several layers of the catalyst [18,19,26]. Figure 6a shows C 1s XPS spectra acquired at room temperature after reaction and after flashing the Pd(100) catalyst to various temperatures.…”

Section: Xpsmentioning

confidence: 99%

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Kinetic and Spectroscopic Studies of Vinyl Acetate Synthesis Over Pd(100)

et al. 2006

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A kinetic study of vinyl acetate (VA) synthesis over a Pd(100) catalyst is described, and the effect of particle-size on this reaction ascertained by comparing the single crystal data with data from supported Pd catalysts (5 wt% Pd/SiO 2 , d Pd =4.2 nm, and 1 wt% Pd/SiO 2 , d Pd =2.5 nm). A negative reaction order with respect to ethylene and a positive order with respect to oxygen were found for the model and supported catalytic systems, whereas the catalytic stability was strongly dependent on the particle size. The mechanism for VA synthesis is proposed to be identical on all catalysts studied based on the similarities of the kinetic parameters. Carbon-containing species on the poisoned Pd(100) catalyst were investigated by X-ray photoelectron spectroscopy (XPS), and the coverage was estimated to be approximately 1.5 ML after VA synthesis.KEY WORDS: kinetics of vinyl acehate synthesis; Pd(100) catalysts.

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Section: Xpssupporting

confidence: 92%

Section: Xpsmentioning

confidence: 99%

Section: Xpsmentioning

confidence: 99%

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Kinetic and Spectroscopic Studies of Vinyl Acetate Synthesis Over Pd(100)

et al. 2006

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“…In order to prove this assumption we increased the carbon content of the surface and near-surface bulk regions by exposing the Pd surface to 6.0 mbar ethene at 493 K prior to reaction. At this temperature ethene decomposes and leaves a carbon-modified surface, but C atoms also migrate into surface near regions of the Pd bulk [15,16,9]. The reaction of 6 mbar ethene with 250 mbar oxygen was now repeated, starting from this 'PdC x ' surface as an initial state.…”

Section: Resultsmentioning

confidence: 99%

Catalytic Oxidation of Ethene on Polycrystalline Palladium: Influence of the Oxidation State of the Surface

et al. 2005

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The partial and total oxidation of ethene was studied on clean and oxidized polycrystalline Pd in a UHV high-pressure cell. The model catalyst was prepared under UHV conditions and characterized by thermal desorption and Auger and Raman spectroscopy. Starting from either a Pd or PdO surface, reaction to CO 2 is the predominant pathway, and acetic acid is the main byproduct between 453 and 523 K. The route to partially oxidized products, in particular acetic acid, is more favoured on the PdO surface, while on Pd metal acetic acid is formed at lower temperatures than on PdO. On stoichiometric PdO activation for both partial and total oxidation occurs during an induction period, until under working conditions Pd metal, PdO, ÔPdC x ' and isolated defects are coexistent on the surface. The presence of an extended metal surface favours the follow-up oxidation of byproducts, while the presence of PdO stabilizes acetic acid far beyond 473 K.

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“…Our work has been conducted solely on single crystals, not on high area catalysts which Han et al [1] used. Nonetheless, we arrive at similar conclusions regarding the importance of carbide formation and the possible role of Au [Bowker et alsubmitted;2]. We have investigated the adsorption, desorption and reaction of a number of relevant organics on Pd(110), including ethene (Bowker et al, submitted), acetic acid, vinyl acetate and even acetaldehyde [3].…”

mentioning

confidence: 80%