Nitroxide complexes with the solid Lewis acids

Lunina, E. V.; Markaryan, G. L.; Паренаго, О. О.; Fionov, A. V.

doi:10.1016/0927-7757(93)80483-u

Cited by 29 publications

(10 citation statements)

References 13 publications

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“…Correlation times were deduced for the probe at each of the two sites, and it was further determined that the enthalpy change incurred in transporting the nitroxide from the surface hydroxyl site (1) to the aluminium centre ( 2) is positive at + 5 kcal mol -1 . Similar Al-complexes were later observed on other surfaces 51,52 , and which, in many ways, resemble complexes of nitroxides with Lewis- acids (e.g. AlCl 3 ) 53 , for which comparable ESR parameters were measured.…”

Section: Nitroxides Sorbed On Surfacessupporting

confidence: 72%

Unpaired Electrons as Probes of Catalytic Systems

Rhodes¹

2014

Science Progress

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An overview is provided of the importance of molecular species containing unpaired electrons in catalytic systems, as revealed using ESR spectroscopy. The review aims to demonstrate the considerable extent of scientific progress that has been made in this broad topic during the past few decades. Studies of catalytically active surfaces, including zeolites, are surveyed, and the detection of radical species, formed as intermediates in their reactions, using matrix isolation and spintrapping techniques. Radical cation formation in zeolites is discussed, and the employment of muon spin rotation and relaxation techniques to study the mobility of labelled radicals in various porous and catalytic media. Among the specific types of catalytic media considered are those for photocatalysis, water splitting, degradation of environmental pollutants, hydrocarbon conversions, fuel cells and sensor devices employing graphene. The review concludes with recent developments in the study of enzymes and their reactions, using ESR-based methods.

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Section: Nitroxides Sorbed On Surfacessupporting

confidence: 72%

Unpaired Electrons as Probes of Catalytic Systems

Rhodes¹

2014

Science Progress

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“…21 The method provides an advantageous means of for example determining the specific surface area or controlling the surface acidity of Lewis acid catalysts.…”

Section: Interactions With Metal Ionsmentioning

confidence: 99%

Nitroxides: Versatile Reporters and Reactants

Zottler

Gescheidt

2011

Journal of Chemical Research

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Evelyn Zottler received her MSc degree in chemistry from the University of Technology in Graz. She participated in a student exchange project with Syracuse University, USA, where she did a research internship in the group of Prof. M. B. Sponsler. She also worked as an IAESTE trainee at the University of Edinburgh, UK, in Dr D. Uhrin's group. She spent a year as an ERASMUS student at the University of Liverpool, UK. For her diploma thesis, she has been working on interactions between metal ions and pH-sensitive imidazoline nitroxides together with Prof. G. Gescheidt at the Institute of Physical and Theoretical Chemistry in Graz.Georg Gescheidt obtained his diploma in chemistry at the Albert-Ludwigs-University in Freiburg (Germany). Then he joined the group of Prof. Fabian Gerson where he obtained his PhD in the field of radical ions and their investigation by EPR spectroscopy. After two years of editorial work at Helvetica Chimica Acta (1988-90), he returned to university life. Since 2003 he has held a chair in Physical Chemistry at the University of Technology in Graz. His research interests are the molecular basis of radical and radical ion reactions in chemistry, catalysis, biomimetic systems and material science (polymer chemistry). Short-lived species are established by magnetic-resonance methods (EPR, ENDOR, time-resolved EPR (ns time scale), CIDNP), theoretical approaches, cyclovoltammetry, and, partly, by optical spectroscopy.

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“…[1] There are many studies devoted to the application of probe EPR in heterogeneous catalysis. [2][3][4][5] Nevertheless, in each case, it is necessary to take into account the peculiarities of the used EPR approaches. The differences in composition and properties of the catalysts require to develop or modify the known approaches taking into account the restrictions on the objects under study and the complexity in the interpretation of obtained EPR spectra.…”

Section: Introductionmentioning

confidence: 99%

The deactivation of acidic sites of NiMo/B₂O₃–Al₂O₃ catalysts during vegetable oil hydrodeoxygenation studied by EPR spectroscopy

Yurpalov

Neponiashchii

Дроздов

et al. 2021

Magnetic Reson in Chemistry

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This paper presents the study results of NiMo/B 2 O 3 -Al 2 O 3 (0-30% wt. of B 2 O 3 ) catalysts for vegetable oil hydrodeoxygenation before and after catalytic tests by different electron paramagnetic resonance (EPR) methodologies. For the initial catalysts, the concentration of Brønsted acidic sites (BAS) determined by probe EPR with perylene increases linearly with an increase in the modifier (B 2 O 3 ) content in the samples. It was found that the isomerization activity of the catalysts increases with increasing the concentration of determined BAS. As for the spent catalysts, linear correlation of paramagnetic species concentration with the content of carbon deposits (determined by thermogravimetric analysis [TGA]/differential thermal analysis [DTA]) was found. The main reasons for the NiMo/B 2 O 3 -Al 2 O 3 catalysts deactivation over the formation of carbon deposits related to the participation of acidic sites (both Lewis and Brønsted) in the polycondensation of hydrocarbons via radical species are also proposed.

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Nitroxide complexes with the solid Lewis acids

Cited by 29 publications

References 13 publications

Unpaired Electrons as Probes of Catalytic Systems

Unpaired Electrons as Probes of Catalytic Systems

Nitroxides: Versatile Reporters and Reactants

The deactivation of acidic sites of NiMo/B₂O₃–Al₂O₃ catalysts during vegetable oil hydrodeoxygenation studied by EPR spectroscopy

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Nitroxide complexes with the solid Lewis acids

Cited by 29 publications

References 13 publications

Unpaired Electrons as Probes of Catalytic Systems

Unpaired Electrons as Probes of Catalytic Systems

Nitroxides: Versatile Reporters and Reactants

The deactivation of acidic sites of NiMo/B2O3–Al2O3 catalysts during vegetable oil hydrodeoxygenation studied by EPR spectroscopy

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Product

Resources

About

The deactivation of acidic sites of NiMo/B₂O₃–Al₂O₃ catalysts during vegetable oil hydrodeoxygenation studied by EPR spectroscopy