NO+CO+O2 Reaction Kinetics on Rh(111): A Molecular Beam Study

Gopinath, Chinnakonda S.; Zaera, Francisco

doi:10.1006/jcat.2001.3215

Cited by 54 publications

(43 citation statements)

References 64 publications

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“…The FEM experimental device, based on the use of sharp field emitter tips, has been described before [16,19]. The molecular beam work was carried out in a separate UHV chamber [5,11]. The crystal was exposed to mixed CO + O 2 molecular beams by using a capillary array doser.…”

Section: Methodsmentioning

confidence: 99%

“…Isothermal, non-linear dynamic processes with H 2 +O 2 , CO+O 2 , NO+H 2 mixtures have been studied on Pd, Rh, Ir and Pt tips in the 10 )7 to 10 )3 torr total pressure regime [3,4], and with molecular beams using single crystals [5][6][7][8][9][10][11][12]. When considering CO oxidation reactions, it is worth noticing that oxygen adsorbs only molecularly at low temperatures (O 2ads , T~100 K), and dissociates above 170 K. Moreover, heating O 2 -dosed surfaces above 170 K results in the desorption of some of the O 2ads molecules.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, different mesoscopic and microscopic analytical tools have been introduced and successfully applied to the study of the details of the dynamics of CO oxidation on palladium and platinum metal surfaces [9,11,16,17]. The aim of our study has been to gain a further understanding of the CO oxidation kinetics at low temperatures, and to determine the role of '' hot'' or ''nascent'' O ads atoms, subsurface atomic oxygen (O sub ), and surface reconstructions in self-oscillatory phenomena during CO oxidation catalyzed by Pd(111), Pd(110) and Pt(100) single crystals and Pt and Pd tip surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Study of the low-temperature reaction between CO and O2 over Pd and Pt surfaces

et al. 2005

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Field electron microscopy (FEM), high-resolution electron energy loss spectroscopy (HREELS), molecular beams (MB) and temperature-programmed reaction (TPR) have been applied to the study of the kinetics of CO oxidation at low temperature, and to determine the roles of subsurface atomic oxygen (O sub ) and surface reconstruction in self-oscillatory phenomena, on Pd(111), Pd(110) and Pt(100) single crystals and on Pd and Pt tip surfaces. It was found that high local concentrations of adsorbed CO during the transition from a Pt(100)-hex reconstructed surface to the unreconstructed 1·1 phase apparently prevents oxygen atoms from occupying hollow sites on the surface, and leads to the appearance of a weakly bound active adsorbed atomic oxygen (O ads ) state in an on-top or bridge position. It was also inferred that subsurface oxygen O sub on the Pd(110) surface may play an important role in the formation of new active sites for the weakly bound O ads atoms. Experiments with 18 O isotope labeling clearly show that the weakly bound atomic oxygen is the active form of oxygen that reacts with CO to form CO 2 at T~140-160 K. Sharp tips of Pd and Pt, several hundreds angstroms in diameter, were used to perform in situ investigations of dynamic surface processes. The principal conclusion from those studies was that non-linear reaction kinetics is not restricted to macroscopic planes since: (i) planes as small as~200 Å in diameter show the same non-linear kinetics as larger flat surfaces; (ii) regular waves appear under conditions leading to reaction rate oscillations; (iii) the propagation of reaction-diffusion waves involves the participation of different crystal nanoplanes via an effective coupling between adjacent planes.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Study of the low-temperature reaction between CO and O2 over Pd and Pt surfaces

et al. 2005

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“…Depending on the NO coverage, the desorption of nitrogen (Eqs. 3,4) takes place at temperatures between 460 and 700 K [5][6][7]. The influence of different surface species on the selectivity of nitrogen desorption towards the formation of N 2 or N 2 O is still under discussion [2].…”

Section: Introductionmentioning

confidence: 99%

“…1) is thermodynamically favoured over the adsorption of O 2 [2,3] and the dissociation step (Eq. 2) takes place at temperatures as low as 300 K and at low NO surface coverages [4]. Depending on the NO coverage, the desorption of nitrogen (Eqs.…”

Section: Introductionmentioning

confidence: 99%

Abatement of NO Using Rhodium Catalysts Supported on Carbon Nanotubes: Carbon as Support Material and Reducing Agent

2009

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NO_x Reduction at Near Ambient Temperatures and Under Lean‐Burn Conditions on Modified Pd Surfaces

Roy

Gopinath

2014

ChemCatChem

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Palladium surfaces that are modified with O atoms in the subsurface broaden the NO reduction temperature regime up to 325 K with O2‐rich NO+H2+O2 compositions. Compared to virgin Pd surfaces, up to 150 % higher deNOx catalytic activity was observed with modified Pd surfaces at the reaction maximum. Molecular beam instrument and ambient‐pressure photoelectron spectroscopy were employed to follow the kinetic and surface changes. These results open up a possibility to realize the cold‐start reduction of NOx (deNOx). DeNOx activity reported in the literature with supported Pd catalysts after a simple calcination in air compares well with our present observations. Surface modification is likely to demonstrate a high potential for other catalytic reactions at relatively low temperatures.

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NO+CO+O2 Reaction Kinetics on Rh(111): A Molecular Beam Study

Cited by 54 publications

References 64 publications

Study of the low-temperature reaction between CO and O2 over Pd and Pt surfaces

Study of the low-temperature reaction between CO and O2 over Pd and Pt surfaces

Abatement of NO Using Rhodium Catalysts Supported on Carbon Nanotubes: Carbon as Support Material and Reducing Agent

NO_x Reduction at Near Ambient Temperatures and Under Lean‐Burn Conditions on Modified Pd Surfaces

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NO+CO+O2 Reaction Kinetics on Rh(111): A Molecular Beam Study

Cited by 54 publications

References 64 publications

Study of the low-temperature reaction between CO and O2 over Pd and Pt surfaces

Study of the low-temperature reaction between CO and O2 over Pd and Pt surfaces

Abatement of NO Using Rhodium Catalysts Supported on Carbon Nanotubes: Carbon as Support Material and Reducing Agent

NOx Reduction at Near Ambient Temperatures and Under Lean‐Burn Conditions on Modified Pd Surfaces

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NO_x Reduction at Near Ambient Temperatures and Under Lean‐Burn Conditions on Modified Pd Surfaces