Effect of multiple sites and competition in adsorption on the kinetics of reactions catalyzed by metals

Frennet, Alfred

doi:10.1016/0021-9517(78)90015-5

Cited by 121 publications

(30 citation statements)

References 7 publications

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“…Solid-state NMR spectroscopy (SS NMR) is a powerful tool for the investigation of heterogeneous catalysts prepared from molecular precursors, especially those synthesized by SOMC 160−163 or catalysts connected through a tether to the surface. 164 Generally, nuclei with spin number I = 1/2, such as 1 H, 13 C, 19 F, 29 Si, 15 N, or 31 P are commonly studied by SS NMR spectroscopy because the resolution is reasonably good, and the interpretation of results straightforward. Study of quadrupolar NMR nuclei with I > 1, such as 11 B (I = 3/ 2), 165 27 Al (I = 5/2), 166,167 17 O (I = 5/2), 168 93 Nb (I = 9/2), 50 etc., 169 is yet rarely reported in literature because SS NMR signals are typically wider due to rapid quadrupolar relaxation.…”

Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

“…1 H, 13 C MAS, and 2D SS NMR. 1 H, 13 C MAS, and two-dimensional SS NMR techniques have become crucial tools for surface sciences, nanotechnology, and heterogeneous catalysis enabling the characterization of welldefined solids, as hybrid materials, grafted linkers, and heterogeneous catalysts. The applications of these techniques in SOMC are numerous.…”

Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

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The Comparison between Single Atom Catalysis and Surface Organometallic Catalysis

et al. 2019

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Single atom catalysis (SAC) is a recent discipline of heterogeneous catalysis for which a single atom on a surface is able to carry out various catalytic reactions. A kind of revolution in heterogeneous catalysis by metals for which it was assumed that specific sites or defects of a nanoparticle were necessary to activate substrates in catalytic reactions. In another extreme of the spectrum, surface organometallic chemistry (SOMC), and, by extension, surface organometallic catalysis (SOMCat), have demonstrated that single atoms on a surface, but this time with specific ligands, could lead to a more predictive approach in heterogeneous catalysis. The predictive character of SOMCat was just the result of intuitive mechanisms derived from the elementary steps of molecular chemistry. This review article will compare the aspects of single atom catalysis and surface organometallic catalysis by considering several specific catalytic reactions, some of which exist for both fields, whereas others might see mutual overlap in the future. After a definition of both domains, a detailed approach of the methods, mostly modeling and spectroscopy, will be followed by a detailed analysis of catalytic reactions: hydrogenation, dehydrogenation, hydrogenolysis, oxidative dehydrogenation, alkane and cycloalkane metathesis, methane activation, metathetic oxidation, CO 2 activation to cyclic carbonates, imine metathesis, and selective catalytic reduction (SCR) reactions. A prospective resulting from present knowledge is showing the emergence of a new discipline from the overlap between the two areas.

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Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

The Comparison between Single Atom Catalysis and Surface Organometallic Catalysis

et al. 2019

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“…Thus, one chemisorbed hydrogen atom can affect the surface properties of the catalyst over a relatively large area, making it energetically favourable for further hydrogen atoms t o stick t o the surface. Metal-hydrogen active sites, consisting of several surface atoms, have been proposed as " h d i n g sites" by Frennet et al [21]. We interpret these landing sites 2,s the delocalization of the hydrogen-metal bond in our exciton-like state extending to several atoms.…”

Section: Surface Catalystsmentioning

confidence: 58%

Subsurface hydrogen exciton‐like states in solid catalysts

Szász

Fabian

1989

Physica Status Solidi (b)

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Subsurface hydrogen electronic levels are discussed in terms of exciton-like states generated by vacancy-hydrogen interaction in transition-metal catalysts. Trapped hydrogen atoms have binding energies that depend exponentially on the density of electronic states a t the Fermi level.Die Elektronenniveaus von Sub-Oberflkichenwasserstoff werden mit Exziton-ahnlichen Zustanden diskutiert, die durch Leerstellen-Wasserstoff-Wechselwirkung in tfbergangsmetallkatalysatoren gebildet werden. Die angehafteten Wasserstoffatome haben Bindungsenergien, die exponentiell von der Dichte der Elektronenzustande am Ferminiveau abhgngen.

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“…The slow step for alkane oxidation has been postulated to be the dissociative chemisorption of the alkane on the catalyst surface, induced by the breakage of the weakest C-H bond [21]. Since propane occupies several active sites on the surface of the catalyst, and its dissociation liberates hydrogen, this process might lead to a higher apparent reaction order, as shown by calculations reported by Frennet et al [26]. An increase in the rate of adsorption/dissociation of propane with propane concentration also explains the increase in PCE conversion with propane content: it is likely that PCE follows a reductive dehalogenation path reacting with the hydrogen produced on the surface by the dissociation of propane.…”

Section: Resultsmentioning

confidence: 99%

Thermocatalytic destruction of gas-phase perchloroethylene using propane as a hydrogen source

Willinger

Rupp

Barbaris

et al. 2009

Journal of Hazardous Materials

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The use of propane in combination with oxygen to promote the destruction of perchloroethylene (PCE) over a platinum (Pt)/rhodium (Rh) catalyst on a cerium/zirconium oxide washcoat supported on an alumina monolith was explored. Conversions of PCE were measured in a continuous flow reactor with residence times less than 0.5 s and temperatures ranging from 200 to 600°C. The presence of propane was shown to increase significantly the conversion of PCE over oxygen-only conditions. Conversions close to 100% were observed at temperatures lower than 450°C with 20% oxygen and 2% propane in the feed, which makes this process attractive from a practical standpoint. In the absence of oxygen, PCE conversion is even higher, but the catalyst suffers significant deactivation in less than an hour. Even though results show that oxygen competes with reactants for active sites on the catalyst, the long-term stability that oxygen confers to the catalyst makes the process an efficient alternative to PCE oxidation. A Langmuir-Hinshelwood competitive adsorption model is proposed to quantify PCE conversion.

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Effect of multiple sites and competition in adsorption on the kinetics of reactions catalyzed by metals

Cited by 121 publications

References 7 publications

The Comparison between Single Atom Catalysis and Surface Organometallic Catalysis

The Comparison between Single Atom Catalysis and Surface Organometallic Catalysis

Subsurface hydrogen exciton‐like states in solid catalysts

Thermocatalytic destruction of gas-phase perchloroethylene using propane as a hydrogen source

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