Zeolite Chemistry of CuZSM-5 Revisited

Jacono, M. Lo; Fierro, and G.; Dragone, Roberto; Feng, Xin; d'Itri, and Julie; Hall, W. Keith

doi:10.1021/jp9632044

Cited by 83 publications

(79 citation statements)

References 20 publications

(55 reference statements)

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“…The EPR intensity have been proven by many groups to decrease upon dehydration compared to the intensity of the hydrated zeolite [11,28,33,44,54]. The first example of this was seen for Cu-FAU (with 2.2-16 Cu 2+ ions per unit cell), which decreases to approximately 55% of the intensity already after heating at 100-120 °C in vacuum.…”

Section: The Decrease In Epr Signal Intensity During Dehydrationmentioning

confidence: 98%

Identification and Quantification of Copper Sites in Zeolites by Electron Paramagnetic Resonance Spectroscopy

et al. 2016

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Recent quantitative electron paramagnetic resonance spectroscopy (EPR) data on different copper species present in copper exchanged in CHA zeolites are presented and put into context with the literature on other copper zeolites. The information were obtained using ex-situ and in-situ EPR on copper ion exchanged into a CHA zeolite with Si/Al = 14±1 to obtain Cu/Al = 0.46 ±0.02. The results shed light on the identity of different copper species present after activation in air. Since the EPR signal is quantifiable, the content of the different EPR active species has been elucidated and Cu 2+ in 2Al positions in the 6-membered rings (6mr) of the CHA structure has been characterized. sites of the CHA structure under the applied conditions.

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Section: The Decrease In Epr Signal Intensity During Dehydrationmentioning

confidence: 98%

Identification and Quantification of Copper Sites in Zeolites by Electron Paramagnetic Resonance Spectroscopy

et al. 2016

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“…Finally, we also have looked in some more detail into the possibilities for charge compensation when Cu(II) is coordinated to an oxygen ring containing only one aluminium. It has been suggested 12,[29][30][31] that Cu(II) coordinated in the proximity of only one Al should carry an OH À group as a fifth ligand, to compensate for the local surplus of positive charge. To check this surmise, we performed additional calculations on two clusters with one Al, placed as in clusters E1 and C1 (represented in Fig.…”

Section: Geometry Optimizationsmentioning

confidence: 99%

The siting of Cu(II) in mordenite: a theoretical spectroscopic study

Delabie

Pierloot

Groothaert

et al. 2001

Phys. Chem. Chem. Phys.

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The siting of Cu(II) in mordenite has been studied by ab initio calculations on large cluster models, representing the cation exchange sites in mordenite. Partial geometry optimizations, based on density functional theory (DFT), were performed to obtain the structure of the coordination environment of Cu(II) at the different sites. The ligand field spectra and EPR g-tensors of these clusters were then calculated by means of multiconfigurational perturbation theory (CASPT2). The calculated results were compared with experimental information, obtained by diffuse reflectance spectroscopy (DRS) and EPR. The calculations indicate that at low exchange levels Cu(II) is coordinated to oxygen six-rings in the main channel of mordenite, in the presence of two aluminiums. At higher loadings, six-or five-rings containing only one aluminium also become occupied, where Cu(II) is coordinated as a single ion, not as (Cu-OH) þ . The calculations indicate also that in fully dehydrated mordenite, the twisted eight-ring (site A) is not occupied by Cu(II).

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“…In the literature, it is often suggested that Cu II ions in the vicinity of only 1 Al are coordinated to an extra-lattice OH Ϫ ligand in order to compensate for the local positive charge. [23,70,128,135] To test this hypothesis, additional calculations were performed for clusters with 1 Al, where Cu II is also coordinated to OH Ϫ . The optimized structures show that the Cu II ion is in a planar threefold coordination environment.…”

Section: Ab Initio Studies Of the Siting Of Cu II In Mordenitementioning

confidence: 99%

The Coordination of CuII in Zeolites − Structure and Spectroscopic Properties

Delabie

Pierloot

Groothaert

et al. 2002

Eur. J. Inorg. Chem.

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Keywords: Zeolites / Copper / Ab initio calculations / Density functional calculations / ESR spectroscopy / UV/Vis spectroscopy / Heterogeneous catalysis Zeolites loaded with transition metal ions are promising heterogeneous catalysts. Knowledge about the location and structure of the metal centers is of paramount importance for the understanding of the catalytic potential of these materials. In this work, the spectroscopic studies of the coordination of Cu II in zeolite A, ZK4, X, Y and mordenite are reviewed. Experimentally, diffuse reflectance spectroscopy [a] teaches general chemistry and computational chemistry. Her main research interest is the application of ab initio methods for the study of spectroscopic and magnetic properties of systems containing transition metals. Marijke H. Groothaert (left center) was born in Neerpelt, Belgium in 1975. In 1998 she received her M. S. degree from the . Since 1998 she is a PhD student at the Center for Surface Chemistry and Catalysis under the supervision of Professor Robert A. Schoonheydt. Her research is concentrated on the coordination of transition metal ions in zeolites and combines spectroscopic techniques with computational methods. Robert A. Schoonheydt (left bottom) received his M. S. degree in 1966 and . Hab. in Leuven, where he teaches quantum chemistry, computational chemistry, and inorganic chemistry. His main research interests are in the application of computational methods in different areas of chemistry.MICROREVIEWS: This feature introduces the readers to the authors' research through a concise overview of the selected topic. Reference to important work from others in the field is included. 515(DRS) and electron spin resonance (ESR) spectroscopy have been applied to study the coordination of Cu II in zeolites. Ab initio calculations on model clusters, representing the Cu II sites in zeolites, are used for the interpretation of the experimental data. The combination of experimental spectroscopic information with theoretical results leads to a new and profound insight into the Cu II −zeolite interaction.

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Zeolite Chemistry of CuZSM-5 Revisited

Cited by 83 publications

References 20 publications

Identification and Quantification of Copper Sites in Zeolites by Electron Paramagnetic Resonance Spectroscopy

Identification and Quantification of Copper Sites in Zeolites by Electron Paramagnetic Resonance Spectroscopy

The siting of Cu(II) in mordenite: a theoretical spectroscopic study

The Coordination of CuII in Zeolites − Structure and Spectroscopic Properties

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