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Hunger, Michael; Seiler, Michael; Horvath, Thomas D.

doi:10.1023/a:1019064003201

Cited by 72 publications

(105 citation statements)

References 21 publications

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“…2 shows a MAS NMR rotor modified for in situ MAS NMR investigations under continuous-flow conditions. 16 With a specially constructed tool, the catalyst is pressed into a hollow cylinder. And the carrier gas loaded with vapors of the reactants is injected into the spinning MAS rotor via the injection tube.…”

Section: Continuous-flow Conditionsmentioning

confidence: 99%

“…[10][11][12][13][14] The most successful and practical design is that reported by Hunger et al directly utilizing the NMR rotor as a fix-bed reactor with continuous flowing of reactants under magic-angle spinning. 11 In some cases, continuous-flow MAS NMR spectroscopy is combined with other analytical techniques such as gas chromatography, 15,16 UV/Vis spectroscopy 17 or laser hyperpolarized xenon 18 to give additional information on the reaction intermediates, products and kinetics. In this review, firstly the experimental setups for in situ MAS NMR are briefly described, then more recent research progress on the applications of in situ MAS NMR in the acidity characterizations, reaction mechanisms and kinetics of some important organic reactions mainly catalyzed by zeolites are summarized.…”

Section: Introductionmentioning

confidence: 99%

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In situsolid-state NMR for heterogeneous catalysis: a joint experimental and theoretical approach

et al. 2012

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In situ solid-state NMR is a well-established tool for investigations of the structures of the adsorbed reactants, intermediates and products on the surface of solid catalysts. The techniques allow identifications of both the active sites such as acidic sites and reaction processes after introduction of adsorbates and reactants inside an NMR rotor under magic angle spinning (MAS). The in situ solid-state NMR studies of the reactions can be achieved in two ways, i.e. under batch-like or continuous-flow conditions. The former technique is low cost and accessible to the commercial instrument while the latter one is close to the real catalytic reactions on the solids. This critical review describes the research progress on the in situ solid-state NMR techniques and the applications in heterogeneous catalysis under batch-like and continuous-flow conditions in recent years. Some typical probe molecules are summarized here to detect the Brønsted and Lewis acidic sites by MAS NMR. The catalytic reactions discussed in this review include methane aromatization, olefin selective oxidation and olefin metathesis on the metal oxide-containing zeolites. With combining the in situ MAS NMR spectroscopy and the density functional theoretical (DFT) calculations, the intermediates on the catalyst can be identified, and the reaction mechanism is revealed. Reaction kinetic analysis in the nanospace instead of in the bulk state can also be performed by employing laser-enhanced MAS NMR techniques in the in situ flow mode (163 references).

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Section: Continuous-flow Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In situsolid-state NMR for heterogeneous catalysis: a joint experimental and theoretical approach

et al. 2012

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“…9a und 9b) dominiert die Umsetzung von Methanol zu DME. Dies wird sowohl durch die Online-GC-Analyse als auch durch die 13 C-MAS-NMR-Signale von Methanol bei 50 ppm und DME bei 61 ppm belegt. Bereits bei einer Reaktionstemperatur von 473 K ist im UV/VIS-Spektrum das Auftreten einer schwachen Bande bei 245 nm zu beobachten, die Dienen zuzuordnen ist [37].…”

Section: In Den Letztenunclassified

“…Nach Erhöhung der Reaktionstemperatur auf 573 K (s. Abb. 9c) treten neue 13 doch fast keine Veränderung der Bande der polycyclischen Aromaten bei 400 nm zu beobachten.…”

Section: In Den Letztenunclassified

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Moderne Methoden der In‐situ‐Festkörper‐NMR‐Spektroskopie in der heterogenen Katalyse

Hunger

2007

Chemie Ingenieur Technik

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Catalyst Characterization—Heterogeneous

Stavitski

Beale

Weckhuysen

2010

Encyclopedia of Catalysis

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The study of catalysts under in‐situ conditions enables the catalyst scientist to identify and understand the important steps, e.g., the formation of important reaction intermediates and active sites, and stages in a catalyst?s lifetime, such as activation/deactivation. The development of characterization methods as well as the design and construction of appropriate in‐situ cells and reactor probes are inevitable in order to obtain such insight. Both spectroscopic and scattering techniques have been used in attempt to understand quantitative structure/composition‐activity/selectivity relationships in catalysis. Armed with such detailed knowledge about the catalyst, it is then possible for scientists to design, in a more rational way, new and efficient catalysts for sustainable production of bulk and fine chemicals as well as for the removal of harmful compounds in industrial catalytic processes. This chapter provides an overview of the in‐situ characterization techniques available for investigation of catalytic materials. The possibilities and limitations of the methods are discussed and illustrated with numerous case studies.

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Untitled

Cited by 72 publications

References 21 publications

In situsolid-state NMR for heterogeneous catalysis: a joint experimental and theoretical approach

In situsolid-state NMR for heterogeneous catalysis: a joint experimental and theoretical approach

Moderne Methoden der In‐situ‐Festkörper‐NMR‐Spektroskopie in der heterogenen Katalyse

Catalyst Characterization—Heterogeneous

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