A5073327803- High-pressure geophysics and materials
- Catalytic Processes in Materials Science
- Zeolite Catalysis and Synthesis
- X-ray Diffraction in Crystallography
- Crystal Structures and Properties
- Catalysis and Oxidation Reactions
- Solid-state spectroscopy and crystallography
- Metal-Organic Frameworks: Synthesis and Applications
- Advanced Chemical Physics Studies
- Nanomaterials for catalytic reactions
- Inorganic Fluorides and Related Compounds
- Mesoporous Materials and Catalysis
- Rare-earth and actinide compounds
- Advanced NMR Techniques and Applications
- Heusler alloys: electronic and magnetic properties
- Crystallization and Solubility Studies
- Catalysis and Hydrodesulfurization Studies
- Ammonia Synthesis and Nitrogen Reduction
- Chalcogenide Semiconductor Thin Films
- Crystallography and Radiation Phenomena
- Crystallography and molecular interactions
- Advanced Condensed Matter Physics
- Chemical Synthesis and Characterization
- Chemical Thermodynamics and Molecular Structure
- Advanced X-ray Imaging Techniques
Haldor Topsoe (Denmark)
2013-2023
University of Edinburgh
2004-2014
Scottish Universities Physics Alliance
2007-2013
European Synchrotron Radiation Facility
2008-2009
University of Copenhagen
2003-2006
Lawrence Livermore National Laboratory
2005
Carnegie Institution for Science
2005
Geophysical Laboratory
2005
University of Bayreuth
2005
Bayer (Germany)
2005
For the first time, standard and fast selective catalytic reduction (SCR) of NO by NH3 are described in a complete cycle that is able to produce correct stoichiometry while allowing adsorption desorption stable molecules only. The SCR reaction coupling activation O2 with reaction, enabled release NO2. According scheme, can be divided into an oxidation catalyst + NH3; these steps together constitute cycle. Furthermore, both required reduction, finally, or NO2 leads same state catalyst. These...
Cu-SSZ-13 has been characterized by different spectroscopic techniques and compared with Cu-ZSM-5 Cu-β similar Si/Al Cu/Al ratios prepared the same ion exchange procedure. On vacuum activated samples, low temperature FTIR spectroscopy allowed us to appreciate a high concentration of reduced copper centres, i.e. isolated Cu(+) ions located in environments, able form Cu(+)(N2), Cu(+)(CO)n (n = 1, 2, 3), Cu(+)(NO)n 2) upon interaction N2, CO NO probe molecules, respectively. Low FTIR, DRUV-Vis...
Cu-CHA combines high activity for the selective catalytic reduction (SCR) reaction with better hydrothermal stability and selectivity compared to other copper-substituted zeolites. At same time offers an opportunity unraveling coordination environment of copper centers since zeolite framework is very simple only one crystallographically independent tetrahedral site (T-site). In this study results X-band electron paramagnetic resonance (EPR) investigation ion-exchanged a Si/Al ratio 14 ± 1...
The Dark Crystal: A hybrid material is reported that comprised of 1–2 nm sized gold nanoparticles, accessible only through zeolite micropores in a silicalite-1 crystal, as shown by three-dimensional TEM tomography (see picture). Calcination experiments indicate the embedded nanoparticles are highly stable towards sintering. Detailed facts importance to specialist readers published "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available...
Sodium exhibits a pronounced minimum of the melting temperature at approximately 118 gigapascals and 300 kelvin. Using single-crystal high-pressure diffraction techniques, we found that sodium curve is associated with concentration seven different crystalline phases. Slight changes in pressure and/or induce transitions between numerous structural modifications, several which are highly complex. The complexity phase behavior above 100 suggests extraordinary liquid solid states extreme...
Accurate structural models of reaction centres in zeolite catalysts are a prerequisite for mechanistic studies and further improvements to the catalytic performance. The Rietveld/maximum entropy method is applied synchrotron powder X-ray diffraction data on fully dehydrated CHA-type zeolites with without loading catalytically active Cu 2+ selective reduction NO x NH 3 . identifies known sites six-membered ring not previously observed site eight-membered ring. sum refined occupancies these...
The effect of the gas phase during solid-state ion-exchange copper into zeolites was studied by exposing physical mixtures oxides (CuI2O and CuIIO) (MFI, *BEA, CHA) to various combinations NO, NH3, O2, H2O. It is shown that heating these 250 °C results in active catalysts for selective catalytic reduction NO with NH3 (NH3-SCR), indicating Cu has become mobile at temperature. Such treatment allows a fast (<5–10 h) preparation copper-exchanged zeolites. Scanning transmission electron...
Zeolite ZSM-5 is one of the most widely used zeolites, in particular heterogeneous catalysis. This work investigates incorporation Al silica framework monoclinic and speciation during steam treatment for four samples with different Si/Al ratios, using ultrahigh field 27Al NMR (22.3 T), 29Si NMR, X-ray diffraction, IR spectroscopy. MQMAS at 22.3 T allows identification quantification 10 distinct tetrahedral resonances which are assigned to crystallographic sites by their average T–O–T angles,...
ZSM-5 is a widely used zeolite catalyst and employed industrially for the methanol to gasoline (MTG) process. Even so, deactivation of by coke formation constitutes major technical also fundamental challenge. We investigate range catalysts through catalytic testing, physicochemical characterization, powder X-ray diffraction (XRD). It demonstrated that unit cell changes upon deactivation. Periodic density functional theory show change induced certain methyl substituted benzenes in channel...
Using quasi-simultaneous in situ PXRD and XANES, the direct correlation between oxidation state of Cu ions commercially relevant deNOx NH3 -SCR zeolite catalyst Cu-CHA ion migration zeolitic pores was revealed during catalytic activation experiments. A comparison with recent reports further reveals high sensitivity redox-active centers concerning heating rates, temperature, gas environment activation. Previously, Cu+ confirmed present only 6R. Results verify a novel 8R monovalent site, an...
Experimentally, we have found that among the "complicated" phases of potassium at intermediate pressures is one which has same space group as double hexagonal-close-packed structure, although its atomic coordination completely different. Calculations on this P6(3)/mmc (hP4) structure a function pressure show three isostructural transitions and distinctive types chemical bonding: free electron, ionic, metallic. Interestingly, relationships between localized metallic structures ionic compounds...
At pressures above a megabar (100 GPa), sodium crystallizes in number of complex crystal structures with unusually low melting temperatures, reaching as 300 K at 118 GPa. We have utilized this unique behavior extreme to grow single 108 GPa, and investigated the structure pressure using high-intensity x-rays from new Diamond synchrotron source, combination cell wide angular apertures. confirm that, is isostructural cI16 phase lithium, we refined full phase. The results demonstrate extension...
Es muss passen: Das vorgestellte Hybridmaterial besteht aus 1–2 nm großen Goldnanopartikeln, die nur über Zeolithmikroporen in einem Silicalit-1-Kristall zugänglich sind, wie dreidimensionale TEM-Tomographie belegt (siehe Bild). In Kalzinierungsexperimenten waren eingebetteten Nanopartikel gegenüber Sintern sehr stabil.
Synchrotron single-crystal diffraction data show that sodium transforms from the oP8 structure to an incommensurate host-guest composite above 125 GPa in which guest component is nearly ``melted.'' At 147 GPa, correlation length between chains only $28(3)\phantom{\rule{0.3em}{0ex}}\text{\AA{}}$, or approximately six times chain spacing. This configuration shows a wide range of stability at least 155 and 550 K. The transition this phase accompanied by marked decrease optical reflectivity....
The deactivation of zeolite catalyst H-ZSM-5 by coking during the conversion methanol to hydrocarbons was monitored high-energy space- and time-resolved operando X-ray diffraction (XRD) . Space resolution achieved continuous scanning along axial length a capillary fixed bed reactor with time 10 s per scan. Using real structural parameters obtained from XRD, we can track development coke at different points in link this kinetic model correlate changes occurring material. "burning cigar" is...
Molybdenum loss, phase transformations and catalytic performance of an iron molybdate catalyst.
We describe an x-ray diffraction study of liquid Cs at high pressure and temperature conducted in order to characterize the structural changes associated with complex melting curve phase transitions observed solid phases. At 3.9 GPa we observe a discontinuity density accompanied by decrease coordination number from about 12 8, which marks change nonsimple liquid. The specific volume Cs, combined analysis data, strongly suggest existence $ds{p}^{3}$ electronic hybridization above GPa, similar...
Ab initio electronic structure calculations on potassium at high pressure reveal that the orthorhombic $oP8$ structure, found recently in sodium, has a lower enthalpy than do other candidate crystal structures reported to be stable [Y. Ma, A. R. Oganov, and Y. Xie, Phys. Rev. B 78, 014102 (2008)]. Subsequent powder-diffraction studies above 100 GPa confirm phase of from 54(2) 90(2) GPa, where it transforms tetragonal $tI4$ which turn $oC16$ 96(3) GPa.