Mordenite acidity: dependence on the silicon/aluminum ratio and the framework aluminum topology. 2. Acidity investigations

Stach, H.; Jaenchen, J.; Jerschkewitz, Hans Georg; Lohse, U.; Parlitz, B.; Hunger, Michael

doi:10.1021/j100200a051

Cited by 59 publications

(46 citation statements)

References 8 publications

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“…H,Na-Y in turn was assumed to exhibit lower strength and activity of OH groups than mordenite (Si/AI = 5). Moreover, an increase of acidity strength and activity was reported for an increase of dealumination of the framework of R,Na-Y [70][71][72][73][74]. In this context, the strength of the acidity of the respective zeolites has usually been characterized by titration with bases, temperature-programmed desorption of ammonia or pyridine and/or micro calorimetric measurements of the differential heats of adsorption of such probe molecules (see [70][71][72]74]).…”

Section: Fundamental Stretching Bandsmentioning

confidence: 99%

Characterization of Zeolites — Infrared and Nuclear Magnetic Resonance Spectroscopy and X-Ray Diffraction

Karge¹,

Hunger²,

Beyer³

1999

Catalysis and Zeolites

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Section: Fundamental Stretching Bandsmentioning

confidence: 99%

Characterization of Zeolites — Infrared and Nuclear Magnetic Resonance Spectroscopy and X-Ray Diffraction

Karge¹,

Hunger²,

Beyer³

1999

Catalysis and Zeolites

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“…8 Recently, the acidity of the zeolite Mordenite has been the subject of much research. [9][10][11][12][13][14] In order to gain better insight into the dynamics of vibrational relaxation and the properties of this surface hydroxyl, we performed a time-resolved vibrational study of deuterated hydroxyls.…”

Section: Introductionmentioning

confidence: 99%

Fast energy delocalization upon vibrational relaxation of a deuterated zeolite surface hydroxyl

Bonn

Brugmans

Kleyn

et al. 1995

The Journal of Chemical Physics

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. (1995). Fast energy delocalization upon vibrational relaxation of a deuterated zeolite surface hydroxyl. Chemical Physics, 102(5), 2181-2185. DOI: 10.1063/1.468740 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. In this time-resolved study of vibrational dynamics of deuterated surface hydroxyls at acid sites in the zeolite Mordenite, we investigate the O-D T 1 vibrational lifetime and transient band shifts. It is shown that after infrared excitation of the stretching mode of a surface hydroxyl, the excess energy is rapidly distributed over delocalized low-energy lattice modes upon de-excitation. This is asserted from the observation that nonexcited hydroxyls are perturbed by the relaxation of their excited counterparts immediately after this relaxation. This observation can be made owing to better resolution in transient transmission spectroscopy obtained by deuteration of the surface hydroxyls. This assignment allows for accurate estimates of lattice temperatures after relaxation of the vibration. Further, from the observation that the vibrational lifetime is dependent on frequency ͑increasing from 25 to 70 ps with increasing frequency͒, it is concluded that the deuterated acidic protons are hydrogen bonded to lattice oxygen atoms in the zeolite.

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“…Electrophoretic measurements were carried out on commercial, untreated silicas to show that each has a characteristic mobility-pH profile that depends on the manufacturing process used. The acidity of the surface silanol groups depends on the nature of cations in the silica, and especially if aluminum is inserted into the silica backbone network [11]. Heterogeneity of the silica surface can occur as a result of different types of acidic sites, for example, single (unbonded) silanol groups or metal hydroxides with different acidities adjacent to silicon atoms [12].…”

Section: Resultsmentioning

confidence: 99%

The characterization of silica microparticles by electrophoretic mobility measurements

Dietrich¹,

Lerche²,

Reusch³

et al. 1997

Chromatographia

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SummaryElectrophoretic mobility measurements in the pH 2-10 range are described for several commercial HPLC silica microparticles and a laboratory-produced product. The content of metal impurities for the silicas was also determined by AAS. An acidic/hydrothermal treatment was used to generate a more homogenous surface for some of the silicas. The zero points of charge (zpc) for both a native and a treated silica plus several commercial HPLC silicas were compared. The electrophoretic mobility method may be useful in predicting the utility of certain types of silica supports for chromatographic separations.

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Mordenite acidity: dependence on the silicon/aluminum ratio and the framework aluminum topology. 2. Acidity investigations

Cited by 59 publications

References 8 publications

Characterization of Zeolites — Infrared and Nuclear Magnetic Resonance Spectroscopy and X-Ray Diffraction

Characterization of Zeolites — Infrared and Nuclear Magnetic Resonance Spectroscopy and X-Ray Diffraction

Fast energy delocalization upon vibrational relaxation of a deuterated zeolite surface hydroxyl

The characterization of silica microparticles by electrophoretic mobility measurements

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