Influence of Cluster Size Distribution on Cluster Size Dependent Catalytic Kinetics

Murzin, Dmitry Yu.; Simakova, Irina L.

doi:10.1007/s10562-011-0577-3

Cited by 5 publications

(3 citation statements)

References 22 publications

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“…Noteworthy here is evidence suggesting that the larger nanoparticles, C, can be more active catalysts, apparently due to weaker metal−ligand bond energies in the larger nano-particles as elucidated and discussed elsewhere. [4][5][6]18 Also noteworthy is that the B + B → C step is particle-size distribution defocusing, while the B + C → 1.5C autocatalytic step is particle-size distribution focusing. Evidence for particlesize distribution focusing come from our previous observation that when a B + C → 1.5C step is dominant, a decrease in particle-size dispersity is seen (e.g., from 21% to 7.1%).…”

Section: ■ Introductionmentioning

confidence: 99%

A Four-Step Mechanism for the Formation of Supported-Nanoparticle Heterogenous Catalysts in Contact with Solution: The Conversion of Ir(1,5-COD)Cl/γ-Al₂O₃to Ir(0)_∼170/γ-Al₂O₃

2014

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Product stoichiometry, particle-size defocusing, and kinetic evidence are reported consistent with and supportive of a four-step mechanism of supported transition-metal nanoparticle formation in contact with solution: slow continuous nucleation, A → B (rate constant k1), autocatalytic surface growth, A + B → 2B (rate constant k2), bimolecular agglomeration, B + B → C (rate constant k3), and secondary autocatalytic surface growth, A + C → 1.5C (rate constant k4), where A is nominally the Ir(1,5-COD)Cl/γ-Al2O3 precursor, B the growing Ir(0) particles, and C the larger, catalytically active nanoparticles. The significance of this work is at least 4-fold: first, this is the first documentation of a four-step mechanism for supported-nanoparticle formation in contact with solution. Second, the proposed four-step mechanism, which was obtained following the disproof of 18 alternative mechanisms, is a new four-step mechanism in which the new fourth step is A + C → 1.5C in the presence of the solid, γ-Al2O3 support. Third, the four-step mechanism provides rare, precise chemical and kinetic precedent for metal particle nucleation, growth, and now agglomeration (B + B → C) and secondary surface autocatalytic growth (A + C → 1.5C) involved in supported-nanoparticle heterogeneous catalyst formation in contact with solution. Fourth, one now has firm, disproof-based chemical-mechanism precedent for two specific, balanced pseudoelementary kinetic steps and their precise chemical descriptors of bimolecular particle agglomeration, B + B → C, and autocatalytic agglomeration, B + C → 1.5C, involved in, for example, nanoparticle catalyst sintering.

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Section: ■ Introductionmentioning

confidence: 99%

A Four-Step Mechanism for the Formation of Supported-Nanoparticle Heterogenous Catalysts in Contact with Solution: The Conversion of Ir(1,5-COD)Cl/γ-Al₂O₃to Ir(0)_∼170/γ-Al₂O₃

2014

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“…To account for several shapes with independent distributions, one can sum over the morphology: where i is one of many possible shapes, perhaps those studied herein. This may provide a method of approach for gold nanoclusters with several types of polyhedra.…”

Section: Resultsmentioning

confidence: 99%

“…B. To account for several shapes with independent distributions, one can sum over the morphology [77]:…”

Section: Au-co Oxidationmentioning

confidence: 99%

Coordination-Dependent Kinetics in the Catalysis of Gold Nanoclusters

2021

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A coordination-based kinetic model was used to explore the turnover frequency (TOF) in the oxidation of carbon monoxide on gold polyhedral nanoclusters. The Debye energy model was used to determine the Gibbs energy of bare nanoclusters. An empirical energy model derived from density functional theory (DFT) and thermodynamics was used to determine the size dependence of the Gibbs adsorption energy. A thermodynamic approach was used to model the kinetics of CO oxidation on gold nanoclusters. The adsorption was modeled with a Langmuir-Hinshelwood (L-H) mechanism, and also a mechanism (Eley-Rideal, E-R) where oxygen interacts with sites on the cluster support. The coordination, shape, and the Gibbs energy of adsorption were found to be important factors in replicating experimental TOF dependencies. The data from the L-H mechanism was shown to model the experimental results more closely. The mass activity of icosahedra for this reaction shows a good similarity with the experimental data. This work provides guidance for different distributions due to shape and size when determining the TOF and the mass activity.

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Kinetics of cluster shape sensitive heterogeneous catalytic reactions

Murzin¹

2021

Chemical Engineering Journal

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Influence of Cluster Size Distribution on Cluster Size Dependent Catalytic Kinetics

Cited by 5 publications

References 22 publications

A Four-Step Mechanism for the Formation of Supported-Nanoparticle Heterogenous Catalysts in Contact with Solution: The Conversion of Ir(1,5-COD)Cl/γ-Al₂O₃to Ir(0)_∼170/γ-Al₂O₃

A Four-Step Mechanism for the Formation of Supported-Nanoparticle Heterogenous Catalysts in Contact with Solution: The Conversion of Ir(1,5-COD)Cl/γ-Al₂O₃to Ir(0)_∼170/γ-Al₂O₃

Coordination-Dependent Kinetics in the Catalysis of Gold Nanoclusters

Kinetics of cluster shape sensitive heterogeneous catalytic reactions

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Influence of Cluster Size Distribution on Cluster Size Dependent Catalytic Kinetics

Cited by 5 publications

References 22 publications

A Four-Step Mechanism for the Formation of Supported-Nanoparticle Heterogenous Catalysts in Contact with Solution: The Conversion of Ir(1,5-COD)Cl/γ-Al2O3to Ir(0)∼170/γ-Al2O3

A Four-Step Mechanism for the Formation of Supported-Nanoparticle Heterogenous Catalysts in Contact with Solution: The Conversion of Ir(1,5-COD)Cl/γ-Al2O3to Ir(0)∼170/γ-Al2O3

Coordination-Dependent Kinetics in the Catalysis of Gold Nanoclusters

Kinetics of cluster shape sensitive heterogeneous catalytic reactions

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Product

Resources

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A Four-Step Mechanism for the Formation of Supported-Nanoparticle Heterogenous Catalysts in Contact with Solution: The Conversion of Ir(1,5-COD)Cl/γ-Al₂O₃to Ir(0)_∼170/γ-Al₂O₃

A Four-Step Mechanism for the Formation of Supported-Nanoparticle Heterogenous Catalysts in Contact with Solution: The Conversion of Ir(1,5-COD)Cl/γ-Al₂O₃to Ir(0)_∼170/γ-Al₂O₃