Spacial constraint in ZSM-5 zeolite as studied by electron spin resonance

Sendoda, Yoko; Ono, Yoshio

doi:10.1016/0144-2449(86)90050-3

Cited by 30 publications

(27 citation statements)

References 14 publications

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“…Photoluminescence measurements of Cu + cations have identified four individual types of Cu + cation in reduced ZSM-5 and mordenite (12), whose population depends upon the Cu loading, the framework Si/Al ratio and the type of framework. Electron spin resonance spectroscopy (ESR) provides evidence for at least two distinct sites in dehydrated Cu-ZSM-5 (12)(13)(14) and Cu-mordenite (12,15). The two sites in the former are believed to have square planar and square pyramidal coordination, although their exact nature is unclear.…”

Section: Introductionmentioning

confidence: 99%

On the Nature of Nonframework Cations in a Zeolitic deNOx Catalyst: Cu-Mordenite

Attfield

Weigel

Cheetham

1997

Journal of Catalysis

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Section: Introductionmentioning

confidence: 99%

On the Nature of Nonframework Cations in a Zeolitic deNOx Catalyst: Cu-Mordenite

Attfield

Weigel

Cheetham

1997

Journal of Catalysis

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“…Mordenite has a 12-ring main channel, while ZSM-5 has a 10-ring main channel. Interestingly however, Cu(II) exchanged into ZSM-5 has more coordinated ligands than does Cu(II) exchanged into mordenite [45][46][47][48]. This is because Cu(II) in mordenite forms a coordination complex in more constricted sites off the main channel, while Cu(II) in ZSM-5 forms a complex at the wider intersection of two channels [45,46].…”

Section: Discussionmentioning

confidence: 86%

“…The same is true for Pd-exchanged SAPO-5 and Pd-exchanged SAPO-II [52][53][54]. But Cu(II) in SAPO-II coordinates with [45] [45] [ [46][47][48] [511 [52,53] [541 [55] [56]…”

Section: Discussionmentioning

confidence: 88%

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Adsorbate interactions of Cu(II) in Cu(II)-exchanged K-L gallosilicate studied by CW and Pulsed electron spin resonance

Yu¹,

Hong

Kevan

1996

Appl. Magn. Reson.

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The interactions of Cu(II) in Cu(II)-exchanged K-L gallosilicate with adsorbates containing coordinative nitrogens in ammonia, pyridine, aniline, acetonitrile and hydrazine, and with the adsorbates carbon monoxide, benzene, propanol and dimethyl sulfoxide ate investigated by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies. These results are compared with those in Cu(II)-exchanged K-L aluminosilicate and the differences are discussed. Adsorption of ammonia produces a complex comaining four molecules of ammonia based on resolved nitrogen superhyperfine imeraction. Upon equilibrium with pyridine, Cu(II) forms a complex containing four molecules of pyridine in CuK-L gallosilicate and a complex containing only three molecules of pyridine in CuK-L aluminosilicate based on resolved nitrogen superhyperfine. Upon adsorption of aniline and acetonitrile, Cu(II) forms complexes containing two molecules of each in CuK-L gallosilicate based on resolved nitrogen superhyperfine. However, no resolved nitrogen superhyperfine between hydrazine and Cu(II) is seen. Adsorption of carbon monoxide, benzene, propanol and dimethyl sulfoxide causes changes in the ESR spectrum of Cu(II), indicating migration of Cu(II) into cation positions in the main channels where adsorbate coordination can occur. Cu(II) forms complexes with one moleeule of benzene and two molecules of propanol based on ESEM data in both K-L gallosilicate and K-L aluminosilicate. However, Cu(II) interacts directly with one dimethyl sulfoxide in K-L aluminosilicate but only indirectly at a longer distance with one dimethyl sulfoxide in K-L gallosilicate based on ESEM data.

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“…Copper(II) pyridine complexes with different numbers of coordinated pyridine molecules have been studied in various molecular sieve materials such as NaX, 12 NaY, 13,14 ZSM-5 8,9 zeolites, VPI-5, ,15 SAPO-n, 10,15 pillared clays11 and MCM-41 16 by means of CW ESR. Among these host materials the formation of the common tetrapyridine copper(II) complex could only be detected in NaX, NaY, pillared clays, and MCM-41 on the basis of the number of resolved nitrogen super hyperfine (shf) structure lines in the ESR spectrum.…”

Section: Introductionmentioning

confidence: 99%

A Study of the Coordination Geometry of the Tetrapyridine Copper(II) Complex in NaY and MCM-41 by Two-Dimensional Electron Spin Resonance HYSCORE Spectroscopy

Pöppl¹,

Gutjahr²,

Hartmann³

et al. 1998

J. Phys. Chem. B

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The coordination geometry of the tetrapyridine copper(II) complex in zeolite Cu-NaY and mesoporous siliceous MCM-41 material is investigated by two-dimensional proton and deuterium hyperfine sublevel correlation (HYSCORE) spectroscopy. Different orientations of the pyridine ligands with respect to the complex plane of the tetrapyridine copper(II) complex were found in the two materials. The ligands are predominately arranged with their molecular plane perpendicular to the complex plane in zeolite Cu-NaY. Otherwise, in Cu-MCM-41 materials the ligands have a mean orientation of their molecular plane parallel to the complex plane. However, the two-dimensional hyperfine sublevel correlation spectra reveal severe distortions of the overall complex. The different coordination geometries of the tetrapyridine copper(II) complex in both materials result from the interaction of the complex with the inner surface of each molecular sieve. Consequently, much severe distortion of the complex geometry was found in the mesoporous Cu-MCM-41 material with its amorphous wall structure in comparison to crystalline Y zeolite. The incorporation of the tetrapyridine Cu(II) complex into Y zeolite also alters the electron spin density distribution within the complex. The results indicate a substantial influence of the framework of the Y zeolite on the unpaired electron of the encapsulated complex.

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Spacial constraint in ZSM-5 zeolite as studied by electron spin resonance

Cited by 30 publications

References 14 publications

On the Nature of Nonframework Cations in a Zeolitic deNOx Catalyst: Cu-Mordenite

On the Nature of Nonframework Cations in a Zeolitic deNOx Catalyst: Cu-Mordenite

Adsorbate interactions of Cu(II) in Cu(II)-exchanged K-L gallosilicate studied by CW and Pulsed electron spin resonance

A Study of the Coordination Geometry of the Tetrapyridine Copper(II) Complex in NaY and MCM-41 by Two-Dimensional Electron Spin Resonance HYSCORE Spectroscopy

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