Heats of Adsorption of Linear and Multibound Adsorbed CO Species on a Pt/Al2O3 Catalyst Using in Situ Infrared Spectroscopy under Adsorption Equilibrium

Bourane, Abdennour; Dulaurent, Olivier; Bianchi, Daniel

doi:10.1006/jcat.2000.3030

Cited by 94 publications

(150 citation statements)

References 49 publications

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“…81,82 This results in higher C-O frequencies for hybrid than nonhybrid functionals. Compared to the experimental values 61,68 of ∼2070-2075 cm -1 for CO adsorbed on alumina-supported Pt nanoparticles, B3LYP is the most accurate, predicting a frequency ∼15 cm -1 higher. B3P86 and PBE1PBE overestimate the frequency by ∼40 and ∼50 cm -1 , respectively, while PBE, PW91, and BPW91 all underestimate the frequency by ∼50 cm ), calculations performed using B3LYP, B3P86, and PBE1PBE predict frequencies ∼50, ∼65, and ∼80 cm -1 higher, respectively.…”

Section: ' Appendixmentioning

confidence: 75%

“…61 However, oxide supports can alter the catalytic properties of the supported metals, so it is possible that this is not a valid comparison. The CO adsorption The Journal of Physical Chemistry C ARTICLE energy on Pt(111) is ∼1.9 eV, 62 and DFT calculations have shown that as cluster sizes decrease the CO adsorption energy increases relative to that on Pt(111), 63 in qualitative agreement with our results.…”

Section: 50mentioning

confidence: 99%

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CO Adsorption on Noble Metal Clusters: Local Environment Effects

et al. 2011

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Bimetallic catalysts are useful because of their versatility, such as the ability to tune their catalytic activity and selectivity by varying properties such as composition, particle size, and support. 1 In particular, Pt-Au catalysts have been shown to exhibit enhanced activity and selectivity in specific reactions when compared to monometallic catalysts. For example, Dimitratos et al. 2 showed that carbon-supported Pt-Au has higher catalytic activity for the oxidation of glycerol than carbon-supported Pt and that the catalyst preparation method affects the selectivity. Selvarani et al. 3 determined that the optimum Pt:Au ratio for carbon-supported Pt-Au as a direct methanol fuel cell catalyst is 2:1, at which composition the catalyst delivers a peak power density 1.5 times that of pure Pt. Comotti et al. 4 found a turnover frequency of 60 h -1 for the oxidation of glucose over pure platinum, while a Pt-Au alloy with Au:Pt ratio of 2:1 yields a turnover frequency of 924 h -1 . The authors also found that, for 7 different Au:Pt ratios ranging from 4 to 0.25, the minimum and maximum turnover frequencies are 240 and 924 h -1 , observed for Au:Pt ratios of 1 and 2, respectively. It is likely that these results depend on the atomic arrangement on the surface of the bimetallic nanoparticles used as catalysts. Unfortunately, direct experimental visualization of the composition and structure of nanoparticle surfaces is at present problematic, especially at operating conditions. Techniques such as high-energy resonant X-ray diffraction can be used to probe the structure of bimetallic catalysts. 5 Molecular simulations could be useful to interpret such experiments and also identify the local structure of supported mono-and bimetallic nanoparticles. [6][7][8] For example, we have previously used molecular dynamics (MD) simulations to study the effect of composition and support geometry on the properties of Pt-Au nanoparticles containing 250 atoms, 9 finding that it should be possible to tailor the distribution of atoms by manipulating nanoparticle composition and support geometry. This could lead to greater control of catalyst selectivity by maximizing the active sites on the nanoparticle surface that catalyze a certain reaction.In order to link our previous MD results to experimentally verifiable measurements, we report here ab initio density functional theory (DFT) calculations for CO adsorption on Pt-Au clusters. CO is often employed as a probe molecule because its adsorption energy and C-O stretching frequency depend on the adsorption site, as can be observed experimentally via, e.g., Fourier transform infrared spectroscopy. 10 CO adsorption is also important in CO oxidation, which occurs in automobile catalytic converters, 11 in preferential CO oxidation (PROX reaction) in hydrogen feeds, 12 and in CO hydrogenation, the critical step in Fischer-Tropsch processes. 13 DFT has been used to study adsorption of CO on metal surfaces, such as Pt(111), [14][15][16][17] on Pt(111) overlayers, 18,19 and on metal nanoparticles. ...

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Section: ' Appendixmentioning

confidence: 75%

Section: 50mentioning

confidence: 99%

CO Adsorption on Noble Metal Clusters: Local Environment Effects

et al. 2011

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“…Therefore, CO adsorption energy on atom-type Pt catalysts is generally greater than that on Pt particles and their corresponding extended surfaces. 86,87 We also investigated the CDD for all configura- tions of the CO−Pt 2 /PAH complex ( Figure 5). The strong variation in the charge density at the interface is due to the interaction with the PAH surface.…”

Section: Co Adsorption On Carbon-supported Pt Atom and Dimermentioning

confidence: 99%

Influence of Carbon Support on Electronic Structure and Catalytic Activity of Pt Catalysts: Binding to the CO Molecule

2016

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Single-atom catalysts, especially with single Pt atoms, exhibit potentially improved catalytic activity as compared to metal clusters and metal surfaces. Here, the atop and bridged bondings of the CO molecule on the Pt/C system are studied. Vibrational frequencies, Mulliken populations, charge transfer, charge density differences and density of states are examined to determine the influence of the carbon support on electronic properties and catalytic activity of the Pt adatom and dimer. Comparing orbital populations and the amount of electron transfer to/from the CO molecule show that the net amount of electron transfer to the anti-bonding 2π * orbitals of the CO molecule is higher for the supported Pt dimer than for the substrate-free Pt dimer which leads to a lower vibrational frequency and a larger C−O bond distance. The hybridization between the π orbitals of the polycyclic aromatic hydrocarbons surface and the d orbitals of the Pt adatoms is responsible for enhancing the back donation of electrons to the 2π * orbitals of the CO molecule which results in a larger peak below the Fermi level for the 2π * states of the CO molecule in the corresponding density of state analysis. Therefore, it can be concluded that the carbon support significantly enhances the catalytic activity of the Pt atoms in contact with the surface for activating the CO molecule. The calculated C−O vibrational stretching frequencies provide valuable guidance for experiments considering the use of atom-type catalyst as building blocks for designing new catalysts.

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“…This range exists because both of these parameters change as a function of the surface coverage of adsorbed species [40,43,66,[72][73][74][75]…”

Section: Heats Of Adsorptionmentioning

confidence: 99%

“…For CO, the authors employ a lumped approach including both the activation energies for adsorption and desorption. In particular, the literature via Table 2 illustrates that the total adsorption heat of this species changes as a function of surface coverage that varies with temperature [72][73][74]. As a result, the authors model CO adsorption with a temperature dependence:…”

Section: Heats Of Adsorptionmentioning

confidence: 99%

Adaptive Global Carbon Monoxide Kinetic Mechanism over Platinum/Alumina Catalysts

et al. 2013

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Carbon monoxide (CO) oxidation is one of the more widely researched mechanisms given its pertinence across many industrial platforms. Because of this, ample information exists as to the detailed reaction steps in its mechanism. While detailed kinetic mechanisms are more accurate and can be written as a function of catalytic material on the surface, global mechanisms are more widely used because of their computational efficiency advantage. This paper merges the theory behind detailed kinetics into a global kinetic model for the singular CO oxidation reaction while formulating expressions that adapt to catalyst properties on the surface such as dispersion and precious metal loading. Results illustrate that the model is able to predict the light-off and extinction temperatures during a hysteresis experiment as a function of different inlet CO concentrations and precious metal dispersion.

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Heats of Adsorption of Linear and Multibound Adsorbed CO Species on a Pt/Al2O3 Catalyst Using in Situ Infrared Spectroscopy under Adsorption Equilibrium

Cited by 94 publications

References 49 publications

CO Adsorption on Noble Metal Clusters: Local Environment Effects

CO Adsorption on Noble Metal Clusters: Local Environment Effects

Influence of Carbon Support on Electronic Structure and Catalytic Activity of Pt Catalysts: Binding to the CO Molecule

Adaptive Global Carbon Monoxide Kinetic Mechanism over Platinum/Alumina Catalysts

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