Supported Size-Selected Clusters as Sophisticated Model Catalyst Systems at Applied Reaction Conditions

AbstractInverse oxide/metal model systems are frequently used to investigate catalytic structure-function relationships at an atomic level. By means of a novel atomic layer deposition process, growth of single-site Fe1Ox on a Pt(111) single crystal surface was achieved, as confirmed by scanning tunneling microscopy (STM). The redox properties of the catalyst were characterized by synchrotron radiation based ambient pressure X-ray photoelectron spectroscopy (AP-XPS). After calcination treatment at 373 K in 1 mbar O2 the chemical state of the catalyst was determined as Fe3+. Reduction in 1 mbar H2 at 373 K demonstrates a facile reduction to Fe2+ and complete hydroxylation at significantly lower temperatures than what has been reported for iron oxide nanoparticles. At reaction conditions relevant for preferential oxidation of CO in H2 (PROX), the catalyst exhibits a Fe3+ state (ferric hydroxide) at 298 K while re-oxidation of iron oxide clusters does not occur under the same condition. CO oxidation proceeds on the single-site Fe1(OH)3 through a mechanism including the loss of hydroxyl groups in the temperature range of 373 to 473 K, but no reaction is observed on iron oxide clusters. The results highlight the high flexibility of the single iron atom catalyst in switching oxidation states, not observed for iron oxide nanoparticles under similar reaction conditions, which may indicate a higher intrinsic activity of such single interfacial sites than the conventional metal-oxide interfaces. In summary, our findings of the redox properties on inverse single-site iron oxide model catalyst may provide new insights into applied Fe-Pt catalysis.

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Electronic interactions in the vanadium/TiO2(110) and vanadia/TiO2(110) model catalyst systems

Surface Science ◽

10.1016/0039-6028(92)90767-z ◽

1992 ◽

Vol 277 (3) ◽

pp. 263-272 ◽

Cited By ~ 125

Author(s):

Zhaoming Zhang ◽

Victor E. Henrich

Keyword(s):

Model Catalyst ◽

Electronic Interactions ◽

Catalyst Systems

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Deoxydehydration of vicinal diols by homogeneous catalysts: a mechanistic overview

Royal Society Open Science ◽

10.1098/rsos.191165 ◽

2019 ◽

Vol 6 (11) ◽

pp. 191165 ◽

Cited By ~ 5

Author(s):

Kayla A. DeNike ◽

Stefan M. Kilyanek

Keyword(s):

Reaction Mechanism ◽

Product Distribution ◽

Catalytic Cycle ◽

Reaction Conditions ◽

Homogeneous Catalysts ◽

Commodity Chemicals ◽

Reduction Methods ◽

Vicinal Diols ◽

Catalyst Systems

Deoxydehydration (DODH) is an important reaction for the upconversion of biomass-derived polyols to commodity chemicals such as alkenes and dienes. DODH can be performed by a variety of early metal-oxo catalysts incorporating Re, Mo and V. The varying reduction methods used in the DODH catalytic cycle impact the product distribution, reaction mechanism and the overall yield of the reaction. This review surveys the reduction methods commonly used in homogeneous DODH catalyst systems and their impacts on yield and reaction conditions.

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Novel Powder-Supported Size-Selected Clusters for Heterogeneous Catalysis under Realistic Reaction Conditions

The Journal of Physical Chemistry C ◽

10.1021/jp306263f ◽

2012 ◽

Vol 116 (50) ◽

pp. 26295-26299 ◽

Cited By ~ 28

Author(s):

V. Habibpour ◽

M. Y. Song ◽

Z. W. Wang ◽

J. Cookson ◽

C. M. Brown ◽

...

Keyword(s):

Heterogeneous Catalysis ◽

Reaction Conditions ◽

Size Selected Clusters

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Structural and Thermal Properties of Ethylene-Norbornene Copolymers Obtained Using Vanadium Homogeneous and SIL Catalysts

Polymers ◽

10.3390/polym12112433 ◽

2020 ◽

Vol 12 (11) ◽

pp. 2433

Author(s):

Paweł Groch ◽

Anna Bihun-Kisiel ◽

Aleksandra Piontek ◽

Wioletta Ochędzan-Siodłak

Keyword(s):

Thermal Properties ◽

Reactivity Ratio ◽

Proton Nuclear Magnetic Resonance ◽

Sequence Length ◽

Resonance Spectroscopy ◽

Scanning Calorimetry ◽

Reaction Conditions ◽

Copolymer Microstructure ◽

Chain Termination Reaction ◽

Catalyst Systems

The series of ethylene-norbornene (E-NB) copolymers was obtained using different vanadium homogeneous and supported ionic liquid (SIL) catalyst systems. The 13C and 1H NMR (carbon and proton nuclear magnetic resonance spectroscopy) together with differential scanning calorimetry (DSC) were applied to determine the composition of copolymers such as comonomer incorporation (CNB), monomer dispersity (MD), monomer reactivity ratio (re), sequence length of ethylene (le) and tetrad microblock distributions. The relation between the type of catalyst, reaction conditions and on the other hand, the copolymer microstructure, chain termination reaction analyzed by the type of unsaturation are discussed. In addition, the thermal properties of E-NB copolymers such as the melting and crystallization behavior, like also the heterogeneity of composition described by successive the self-nucleation and annealing (SSA) and the dispersity index (DI) were determined.

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A domino reaction for generating β-aryl aldehydes from alkynes by substrate recognition catalysis

Nature Communications ◽

10.1038/s41467-019-12770-w ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Weiwei Fang ◽

Felix Bauer ◽

Yaxi Dong ◽

Bernhard Breit

Keyword(s):

Substrate Recognition ◽

Domino Reaction ◽

Chemical Transformations ◽

Reaction Sequence ◽

Reaction Conditions ◽

Consecutive Reaction ◽

Aryl Aldehydes ◽

Rh Catalyst ◽

Catalyst Systems ◽

Step Control

Abstract The development of universal catalyst systems that enable efficient, selective, and straightforward chemical transformations is of immense scientific importance. Here we develop a domino process comprising three consecutive reaction steps based on the strategy of supramolecular substrate recognition. This approach provides valuable β-aryl aldehydes from readily accessible α-alkynoic acids and arenes under mild reaction conditions, employing a supramolecular Rh catalyst containing an acylguanidine-bearing phosphine ligand. Furthermore, the synthesis of a key intermediate of Avitriptan using this protocol is accomplished. The first step of the reaction sequence is proved to be the regioselective hydroformylation of α-alkynoic acids. Remarkably, molecular recognition of the ligand and the substrate via hydrogen bonding plays a key role in this step. Control experiments indicate that the reaction further proceeds via 1,4-addition of an arene nucleophile to the unsaturated aldehyde intermediate and subsequent decarboxylation.

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