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Schlögl, Robert; Knop‐Gericke, Axel; Hävecker, Michael; Wild, Ute; Frickel, Dietrich; Ressler, Thorsten; Jentoft, Rolf E.; Wienold, Julia; Mestl, Gerhard; Blume, Andreas; Timpe, Olaf; Uchida, Yuji

doi:10.1023/a:1016696400146

Cited by 64 publications

(56 citation statements)

References 35 publications

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“…An adsorbate-type structure of the active site allowing dynamical response will be useful whereas a closely packed 3-D crystalline state will hinder such a process with high activation barriers. Such ''adsorbatelike'' active phases [77,78] can be identified with probe molecule reactions [79][80][81][82][83][84][85][86] and have been rationalized for covering some bulk catalysts [13,42,[87][88][89][90][91] as consequence of surface energy minimization.…”

Section: Size and Functions Of Active Sitesmentioning

confidence: 99%

Active Sites for Propane Oxidation: Some Generic Considerations

Schlögl

2011

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Based on experimental observations about structure and dynamics of the reactive surface of the M1 phase some considerations are made about the nature and size of active sites. In analyzing the stoichiometry of the reactions following activation of propane it occurs that for dehydrogenation small sites are desirable being just sufficient to re-activate oxygen without kinetic hindrance. For deeper oxidation to acrylic acid (AA) the sites should be larger to accommodate all redox equivalents and oxygen species required for one transformation. A qualitative model for size and composition of the active site is made. It is likely that the active site consists on a VxOy species of strictly 2-D nature. This follows the structural suggestion for the active site on the a-b-plane of the M1 structure. The role of Te in moderating the active site is discussed. The suggestions are discussed in comparing requirements for oxidative dehydrogenation of propane (ODP) with those for AA synthesis.

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Section: Size and Functions Of Active Sitesmentioning

confidence: 99%

Active Sites for Propane Oxidation: Some Generic Considerations

Schlögl

2011

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“…[46,79,80] In situ studies cast considerable doubt, however, on the allegation that these solids are active in their as-prepared form; their surfacse seem to exhibit differences from the crystalline bulk, and hence a detailed understanding of their structural dynamics is required to control the genesis and stability of the active sites. [81,82] Another strategy is to reduce the size of the active site to a very small number of atoms to prepare "single-site" catalysts, which offer the chance to exactly control the active site and its environment on the molecular scale. [23,83] The strong structural response of such small entities to changes in the electronic structure associated with the catalytic turnover and the absence of a flexible support structure comparable to that provided by the protein structure of enzymes [84] limits the durability of such bio-inspired structures if they are active, or prevents their catalytic activity if they are fixed too strongly to the support.…”

Section: Alternative Routes To Controlled Synthesismentioning

confidence: 99%

Nanocatalysis: Mature Science Revisited or Something Really New?

2004

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"Nanomania" has reached the area of heterogeneous catalysis. Nanosized catalyst constituents are important for functions that require structural control over several scales of dimension. Nanocatalysis may be understood as a redefinition of catalyst synthesis: multidimensional structural control is exerted by considering catalysts as inorganic polymers rather than as close-packed crystals. Primary, secondary, and tertiary structural hierarchies translate into molecular building blocks and linkers, the defect structure of crystals, and particle morphology. High-throughput techniques and in situ synthetic analysis are the tools required to arrive at better defined catalytic materials that can fulfil the high expectations created by the incorporation of catalysts into the "nano" research field.

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“…Critical to the catalyst performance should be the ease of extraction of oxygen from the system, the oxygen species responsible for the selective oxidation obviously being crucially dependent upon the kind of crystalline lattice it occupies. [10] The chemistry used for the preparation of catalysts is the thermal decomposition of metal nitrate salts into oxides in the presence of citric acid. Menon and Delmon [11] give an overview for the methods of preparing mixed metal oxide systems to be as intimately mixed as possible, and this is one of the favoured methods.…”

Section: The Type Of Catalystsmentioning

confidence: 99%

A Screening Workflow for Synthesis and Testing of 10,000 Heterogeneous Catalysts per Day – Lessons Learned

Duff

Ohrenberg

Voelkening

et al. 2003

Macromol. Rapid Commun.

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Summary: For some years now a trend toward the employment of high‐throughput technologies in the development of new catalysts has been apparent in academic and industrial research. One reason is the unmanageably large parameter space present in heterogeneous catalysis, which implies that an increase in throughput in the preparation and testing of candidate substances is necessary, in order to be able to identify a new catalyst in a practicable amount of time. We have tried to locate the current boundaries in achievable throughput. To this end, we developed a workflow in which 10,000 substances per day were synthesised and their activity tested in a heterogeneously catalysed gas phase reaction (alkene epoxidation). The substances were synthesised by dosing precursor solutions onto a single substrate, using ink‐jet printer technology and subsequent thermal treatment. For the activity testing, the product stream of each candidate was conducted through a detection layer, where the target product was converted into a fluorescent substance. By locally resolved fluorescence spectroscopy a rough assessment of each candidate was possible. Because a throughput of 10,000 substances per day is still not able to map the whole parameter space in a practicable amount of time, we used a combination of evolutionary optimisation and data mining as our experiment design strategy for the reduction of the experimental parameter space. It became apparent that a throughput of 10,000 substances per day was only possible at the cost of abstraction and simplification with a concomitant reduction in knowledge gain per individual experiment. Because not every reaction is suited to be simplified in such a manner, whether a high‐throughput screening approach is effective or not has to be considered on a case by case basis.Methods of synthesis and testing to achieve a throughput of 10,000 catalysts per day.magnified imageMethods of synthesis and testing to achieve a throughput of 10,000 catalysts per day.

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Untitled

Cited by 64 publications

References 35 publications

Active Sites for Propane Oxidation: Some Generic Considerations

Active Sites for Propane Oxidation: Some Generic Considerations

Nanocatalysis: Mature Science Revisited or Something Really New?

A Screening Workflow for Synthesis and Testing of 10,000 Heterogeneous Catalysts per Day – Lessons Learned

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