Spectroscopic Identification of the Active Site for CO Oxidation on Rh/Al2O3 by Concentration Modulation in situ DRIFTS

Cavers, M.; Davidson, J. M.; Harkness, Ian R.; Rees, Lovat V.C.; McDougall, Graham J.

doi:10.1006/jcat.1999.2672

Cited by 41 publications

(26 citation statements)

References 13 publications

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“…In situ infrared studies of CO oxidation over supported Rh catalysts have demonstrated that gem-dicarbonyl CO species, which form on isolated Rh(I) sites, are inactive for oxidation by O 2 , while atop and bridge CO species are both active. 31,32,47 In one study, it was proposed that CO adsorbed at Rh(0) sites is most active, 32 while in another it was proposed to be atop CO adsorbed at Rh(I) sites. 31 In our study, comparing the infrared spectra to CO oxidation results, bridge sites are most active, followed by atop CO adsorbed at Rh(0) sites and then atop CO adsorbed at Rh(I) sites.…”

Section: Comparison Of Infrared Results and Catalytic Activitymentioning

confidence: 99%

“…31,32,47 In one study, it was proposed that CO adsorbed at Rh(0) sites is most active, 32 while in another it was proposed to be atop CO adsorbed at Rh(I) sites. 31 In our study, comparing the infrared spectra to CO oxidation results, bridge sites are most active, followed by atop CO adsorbed at Rh(0) sites and then atop CO adsorbed at Rh(I) sites.…”

Section: Comparison Of Infrared Results and Catalytic Activitymentioning

confidence: 99%

“…For conventionally prepared catalysts, bridge and atop CO are observed, but also peaks at ~2100 and ~2025 cm -1 corresponding to the symmetric and antisymmetric stretches of rhodium gem-dicarbonyl, which entails two CO molecules adsorbed to a single Rh(I) atom 31,47,48 . This type of CO adsorption occurs only on isolated Rh atoms (not on NPs); the absence of these peaks in our spectra attest to the fact that all Rh exists on the support in NP form without any isolated Rh atoms.…”

Section: Diffuse Reflectance Infrared Spectroscopymentioning

confidence: 99%

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Colloidally Synthesized Monodisperse Rh Nanoparticles Supported on SBA-15 for Size- and Pretreatment-Dependent Studies of CO Oxidation

Graß¹,

Zhang²,

Somorjai³

2009

J. Phys. Chem. C

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1A particle size dependence for CO oxidation over rhodium nanoparticles of 1.9 -11.3 nm has been investigated and determined to be modified by the existence of the capping agent, poly(vinylpyrrolidone) (PVP). The particles were prepared using a polyol reduction procedure with PVP as the capping agent. The Rh nanoparticles were subsequently supported on SBA-15 during hydrothermal synthesis to produce Rh/SBA-15 supported catalysts for size-dependent catalytic studies.CO oxidation by O 2 at 40 Torr CO and 100 Torr O 2 was investigated over two series of Rh/SBA-15 catalysts: as-synthesized Rh/SBA-15 covering the full range of Rh sizes and the same set of catalysts after high temperature calcination and reduction. The turnover frequency at 443 K increases from 0.4 to 1.7 s -1 as the particle size decreases from 11.3 to 1.9 nm for the as-synthesized catalysts. For the catalyst series after calcination and reduction, the turnover frequency is between 0.1 and 0.4 s -1 with no particle size dependence. The apparent activation energy for all catalysts is ~ 30 kcal mol -1 and is independent of particle size and thermal treatment. Infrared spectroscopy of CO on the Rh nanoparticles indicates that the heat treatments used influence the mode of CO adsorption. As a result, the particle size dependence for CO oxidation is altered after calcination and reduction of the catalysts.CO adsorbs at two distinct bridge sites on as-synthesized Rh/SBA-15, attributable to metallic Rh(0) and oxidized Rh(I) bridge sites. After calcination and reduction, however, CO adsorbs only at Rh(0) atop sites. The change in adsorption geometry and oxidation activity may be attributable to the interaction between PVP and the Rh surface. This capping agent affect may open new possibilities for the tailoring of metal catalysts using solution nanoparticle synthesis methods.

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Section: Comparison Of Infrared Results and Catalytic Activitymentioning

confidence: 99%

Section: Comparison Of Infrared Results and Catalytic Activitymentioning

confidence: 99%

Section: Diffuse Reflectance Infrared Spectroscopymentioning

confidence: 99%

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Colloidally Synthesized Monodisperse Rh Nanoparticles Supported on SBA-15 for Size- and Pretreatment-Dependent Studies of CO Oxidation

Graß¹,

Zhang²,

Somorjai³

2009

J. Phys. Chem. C

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“…Lastly, Fig. 11 shows the Rh L 3 -edge results from room-temperature exposure of the sample heated to 623 K under H 2 to CO. As has been well documented ( Van't Blik et al, 1983;Johnston & Joyner, 1993;Cavers et al, 1999;Suzuki et al, 2002;Newton et al, 2004[Not in References? ], 2006; Dent et al, 2007), CO regenerates a fraction of the (O)Rh I (CO) 2 Cl through an oxidative re-dispersion, though it occurs in this system only a relatively small degree.…”

Section: Assessment Of Dilution Limitsmentioning

confidence: 89%

“…The chemistry of the supported monomeric (O)Rh I (CO) 2 Cl species is of significant interest in terms of a variety of catalytic reactions and in the oxidative re-dispersion of small Rh particles by CO ( Van't Blik et al, 1983;Johnston & Joyner, 1993;Cavers et al, 1999;Suzuki et al, 2002; Newton et al, 2004 [Not in The parent dimer [Rh I (CO) 2 Cl] 2 sublimes at temperatures not much above ambient and therefore this molecule is easily dosed into a vacuum. In our case this deposition was toAl 2 O 3 powder (Degussa Alu-C) that had been deposited from a suspension in 2-propanol onto a flat Al 2 O 3 plate (Goodfellow) and allowed to dry.…”

Section: In Situ Study Of Gas-solid Interactions: Metallo-organic Chementioning

confidence: 99%

X-ray spectroscopy for chemistry in the 2-4 keV energy regime at the XMaS beamline: ionic liquids, Rh and Pd catalysts in gas and liquid environments, and Cl contamination in γ-Al₂O₃

Thompson

Nguyen

Nicholls

et al. 2015

J Synchrotron Radiat

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Synopsis:The performance of the XMaS beamline for soft X-ray spectroscopy in the 2-4 keV range is assessed with particular relation to in situ studies of functional materials and their chemistry. X-ray spectroscopy for chemistry in the 2-4 keV energy regime at the XMaS beamline: ionic liquids, Rh and Pd catalysts in gas and liquid environments, and Cl contamination in c-Al 2 O 3 How to cite your article in pressYour article has not yet been assigned page numbers, but may be cited using the doi:Thompson, P.B.J., Nguyen, B.N., Nicholls, R., Bourne, R.A., Brazier, J.B., Lovelock, K.R.J., Brown, S.D., Wermeille, D., Bikondoa, O., Lucas, C.A. et al. (2015). J. Synchrotron Rad. 22, doi:10.1107/S1600577515016148.You will be sent the full citation when your article is published and also given instructions on how to download an electronic reprint of your article. Proof instructionsProof corrections should be returned by 22 September 2015. After this period, the Editors reserve the right to publish your article with only the Managing Editor's corrections. Please(1) Read these proofs and assess whether any corrections are necessary.(2) Check that any technical editing queries highlighted in bold underlined text have been answered. (3) Send corrections by e-mail to tw@iucr.org. Please describe corrections using plain text, where possible, giving the line numbers indicated in the proof. Please do not make corrections to the pdf file electronically and please do not return the pdf file. If no corrections are required please let us know.If you wish to make your article open access or purchase printed offprints, please complete the attached order form and return it by e-mail as soon as possible. Thumbnail image for contents pageFiles: s/rv5038/rv5038.3d s/rv5038/rv5038.sgml RV5038 FA IU-1517/10(15)9 1516/52(15)9 () RV5038 http://dx.doi.org/10.1107/S1600577515016148 1 of 14 The 2-4 keV energy range provides a rich window into many facets of materials science and chemistry. Within this window, P, S, Cl, K and Ca K-edges may be found along with the L-edges of industrially important elements from Y through to Sn. Yet, relative to those that cater for energies above ca. 4-5 keV, there are relatively few resources available for X-ray spectroscopy below these energies. In addition, in situ or operando studies become to varying degrees more challenging than at higher X-ray energies due to restrictions imposed by the lower energies of the X-rays upon the design and construction of appropriate sample environments. The XMaS beamline at the ESRF has recently made efforts to extend its operational energy range to include this softer end of the X-ray spectrum. In this report the resulting performance of this resource for X-ray spectroscopy is detailed with specific attention drawn to: understanding electrostatic and charge transfer effects at the S K-edge in ionic liquids; quantification of dilution limits at the Cl K-and Rh L 3 -edges and structural equilibria in solution; in vacuum deposition and reduction of [Rh I (CO) 2 Cl] 2 to -Al 2 ...

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Combining Infrared Spectroscopy with X‐ray Techniques for Interrogating Heterogeneous Catalysts

Newton¹,

Fernández²

2013

In‐situ Characterization of Heterogeneous Catalysts

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Spectroscopic Identification of the Active Site for CO Oxidation on Rh/Al2O3 by Concentration Modulation in situ DRIFTS

Cited by 41 publications

References 13 publications

Colloidally Synthesized Monodisperse Rh Nanoparticles Supported on SBA-15 for Size- and Pretreatment-Dependent Studies of CO Oxidation

Colloidally Synthesized Monodisperse Rh Nanoparticles Supported on SBA-15 for Size- and Pretreatment-Dependent Studies of CO Oxidation

X-ray spectroscopy for chemistry in the 2-4 keV energy regime at the XMaS beamline: ionic liquids, Rh and Pd catalysts in gas and liquid environments, and Cl contamination in γ-Al₂O₃

Combining Infrared Spectroscopy with X‐ray Techniques for Interrogating Heterogeneous Catalysts

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Spectroscopic Identification of the Active Site for CO Oxidation on Rh/Al2O3 by Concentration Modulation in situ DRIFTS

Cited by 41 publications

References 13 publications

Colloidally Synthesized Monodisperse Rh Nanoparticles Supported on SBA-15 for Size- and Pretreatment-Dependent Studies of CO Oxidation

Colloidally Synthesized Monodisperse Rh Nanoparticles Supported on SBA-15 for Size- and Pretreatment-Dependent Studies of CO Oxidation

X-ray spectroscopy for chemistry in the 2-4 keV energy regime at the XMaS beamline: ionic liquids, Rh and Pd catalysts in gas and liquid environments, and Cl contamination in γ-Al2O3

Combining Infrared Spectroscopy with X‐ray Techniques for Interrogating Heterogeneous Catalysts

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Product

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X-ray spectroscopy for chemistry in the 2-4 keV energy regime at the XMaS beamline: ionic liquids, Rh and Pd catalysts in gas and liquid environments, and Cl contamination in γ-Al₂O₃