A5083734676- Catalytic Processes in Materials Science
- Catalysis and Oxidation Reactions
- Zeolite Catalysis and Synthesis
- Metal-Organic Frameworks: Synthesis and Applications
- Metal complexes synthesis and properties
- Catalysis and Hydrodesulfurization Studies
- Nanocluster Synthesis and Applications
- Chemical Thermodynamics and Molecular Structure
- Thermal and Kinetic Analysis
- Crystal structures of chemical compounds
- Mesoporous Materials and Catalysis
- Synthesis and Characterization of Heterocyclic Compounds
- Catalysis for Biomass Conversion
- Lanthanide and Transition Metal Complexes
- Crystallography and molecular interactions
- Chemical Reaction Mechanisms
- Oxidative Organic Chemistry Reactions
- Advanced NMR Techniques and Applications
- Catalysts for Methane Reforming
- Polyoxometalates: Synthesis and Applications
- Crystallization and Solubility Studies
- Covalent Organic Framework Applications
- Electronic and Structural Properties of Oxides
- Chemical and Physical Properties in Aqueous Solutions
- Multicomponent Synthesis of Heterocycles
TU Wien
2022-2024
Technical University of Munich
2014-2023
Fischer (Germany)
2019-2020
Max Planck Computing and Data Facility
2015-2020
Fritz Haber Institute of the Max Planck Society
2013-2018
Universidad de Granada
1983-1994
Abstract Copper-exchanged zeolites with mordenite structure mimic the nuclearity and reactivity of active sites in particulate methane monooxygenase, which are enzymes able to selectively oxidize methanol. Here we show that micropores provide a perfect confined environment for highly selective stabilization trinuclear copper-oxo clusters exhibit high towards activation carbon–hydrogen bonds its subsequent transformation The similarity enzymatic systems is also implied from reversible...
Hydrogen transfer is the major route in catalytic conversion of methanol to olefins (MTO) for formation nonolefinic byproducts, including alkanes and aromatics. Two separate, noninterlinked hydrogen pathways have been identified. In absence methanol, occurs between naphthenes via protonation olefin hydride carbenium ion. A hitherto unidentified pathway involving Lewis Brønsted acid sites dominates as long present reacting mixture, leading aromatics alkanes. Experiments with purely acidic...
Copper oxide clusters synthesized via atomic layer deposition on the nodes of metal–organic framework (MOF) NU-1000 are active for oxidation methane to methanol under mild reaction conditions. Analysis chemical reactivity, in situ X-ray absorption spectroscopy, and density functional theory calculations used determine structure/activity relations Cu-NU-1000 catalytic system. The Cu-loaded MOF contained Cu-oxo a few Cu atoms. was present ambient conditions as mixture ∼15% Cu+ ∼85% Cu2+....
The elementary reactions leading to the formation of first carbon-carbon bond during early stages zeolite-catalyzed methanol conversion into hydrocarbons were identified by combining kinetics, spectroscopy, and DFT calculations. intermediates containing a C-C are acetic acid methyl acetate, which formed through carbonylation or dimethyl ether even in presence water. A series acid-catalyzed including acetylation, decarboxylation, aldol condensation, cracking convert those mixture surface...
Abstract Formaldehyde is an important intermediate product in the catalytic conversion of methanol to olefins (MTO). Here we show that formaldehyde present during MTO with average concentration ~0.2 C% across ZSM-5 catalyst bed up a MeOH 70%. It condenses acetic acid or methyl acetate, carbonylation and DME, into unsaturated carboxylate carboxylic acid, which decarboxylates first olefin. By tracing its reaction pathways 13 C-labeled formaldehyde, it shown reacts alkenes via Prins dienes...
Synthesis conditions direct the speciation of Cu<sup>2+</sup> in Cu-exchanged mordenite zeolite towards active [Cu<sub>3</sub>(μ-O)<sub>3</sub>]<sup>2+</sup> species for methane oxidation to methanol.
Abstract Ethane oxidative dehydrogenation (ODH) is an alternative route for ethene production. Crystalline M1 phase of Mo-V mixed metal oxide excellent catalyst this reaction. Here we show a hydrothermal synthesis method that generates phases with high surface areas starting from poorly soluble oxides. Use organic additives allows control the concentration metals in aqueous suspension. Reactions leading to crystalline take place at 190 °C, i.e., approximately 400 °C lower than under current...
Abstract Aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) has been used to image the basal {001} plane of catalytically relevant M1 phase in MoVTeNb complex oxides. Facets {010}, {120}, and {210} are identified as most frequent lateral termination planes crystals. Combination STEM with He ion (HIM) images, Rietveld analysis, kinetic tests reveals that activation ethane is correlated availability facets {001}, at surface The {120}...
Cu-exchanged zeolites are known to be active in the selective oxidation of methane methanol at moderate temperatures. Among them, mordenite (MOR) is system that has so far shown highest yield per Cu atom. This high efficiency attributed ability MOR selectively stabilize an tricopper cluster with a [Cu3(μ-O)3]2+ structure when activated presence O2 In this study, we investigate elementary steps formation by situ X-ray absorption spectroscopy and ultraviolet–visible spectroscopy. We...
Abstract The elementary reactions leading to the formation of first carbon–carbon bond during early stages zeolite‐catalyzed methanol conversion into hydrocarbons were identified by combining kinetics, spectroscopy, and DFT calculations. intermediates containing a C−C are acetic acid methyl acetate, which formed through carbonylation or dimethyl ether even in presence water. A series acid‐catalyzed including acetylation, decarboxylation, aldol condensation, cracking convert those mixture...
Nickel- and alkali-earth-modified LTA based zeolites catalyze the dimerization of 1-butene in absence Brønsted acid sites. The catalyst reaches over 95% selectivity to n-octenes methylheptenes. ratio these two dimers is markedly influenced by parallel isomerization 2-butene, shifting methylheptene/octene from 0.7 1.4 as conversion increases 35%. At this conversion, thermodynamic equilibrium 90% cis- trans-2-butenes reached. Conversion 2-butene results methylheptene dimethylhexene with rates...
A novel pathway of increasing the surface density catalytically active oxygen radical sites on a MoVTeNb oxide (M1 phase) catalyst during alkane oxidative dehydrogenation is reported. The form when fraction Te4+ reduced and emitted from M1 crystals under catalytic operating conditions, without compromising structural integrity framework. Density functional theory calculations show this Te reduction induces multiple inter-related electron transfers, associated cooperative effects lead to...
Significance Methanol conversion to hydrocarbons has emerged as a key reaction for synthetic energy carriers and light alkenes. The autocatalytic nature complex network make mechanistic understanding very challenging widely debated. Water is not only part of the overall conversion, it also frequently used diluent, influencing, in turn, activity, selectivity, stability catalysts. directly indirectly influences processes that initiate C–C formation via adjusting chemical potential methanol...
A systematic gas phase-dependence of the electron work function, affinity, band bending and high frequency electrical conductivity prospective oxidation catalyst MoVTeNbOx with orthorhombic M1 structure was identified under selective alkane conditions. The measured in a fixed bed flow reactor at 1 bar noncontact microwave technique surface electronic properties studied by situ X-ray photoelectron spectroscopy 0.25 mbar were determined 400 °C 2:1 mixtures oxygen alkanes ethane, propane,...
Copper-oxo clusters exchanged in zeolite mordenite are active the stoichiometric conversion of methane to methanol at low temperatures. Here, we show an unprecedented yield per Cu 0.6, with a 90-95 % selectivity, on MOR solely containing [Cu3 (μ-O)3 ]2+ sites. DFT calculations, spectroscopic characterization and kinetic analysis that increasing chemical potential enables utilization two μ-oxo bridge oxygen out three available tricopper-oxo cluster structure. Methanol methoxy groups...
Cu-zeolites are able to directly convert methane methanol via a three-step process using O2 as oxidant. Among the different zeolite topologies, Cu-exchanged mordenite (MOR) shows highest yields, attributed preferential formation of active Cu–oxo species in its 8-MR pores. The presence extra-framework or partially detached Al entrained micropores MOR leads nearly homotopic redox Cu–Al–oxo nanoclusters with ability activate CH4. Studies activity these sites together characterization by 27Al...