Dynamical studies of zeolitic protons and interactions with adsorbates by picosecond infrared spectroscopy

Bonn, Mischa; Bakker, Huib J.; Kleyn, Aart W.; Santen, Rutger A. van

doi:10.1016/s0169-4332(97)00262-6

Cited by 4 publications

(1 citation statement)

References 29 publications

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“…The frequencies of the observed species and the proposed energy diagram of the formic acid decomposition are also supported by quantum chemical calculations. 10 Although several picosecond vibrational studies have been performed to examine the vibrational relaxation processes of zeolite hydroxyl groups, [11][12][13][14][15][16] the only report in the literature treating the reaction dynamics of other species adsorbed on zeolite surfaces deals with the observation of transients in an isobutene/zeolite system. 8 In that study, the structural change of isobutene adsorbed on zeolite hydroxyl groups was observed on the basis of vibrational excitation of the OH stretching mode.…”

Section: Introductionmentioning

confidence: 99%

Direct Observation of Unstable Intermediate Species in the Reaction of trans-2-Butene on Ferrierite Zeolite by Picosecond Infrared Laser Spectroscopy

et al. 2005

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The reaction dynamics of trans-2-butene adsorbed to acidic hydroxyl groups on the surface of ferrierite zeolite is examined by time-resolved spectroscopy using a tunable infrared picosecond pulse laser system. The transient absorption spectra measured by a two-color pump-probe technique at 188-243 K reveal bleaching and hot bands of the OD stretching mode 2 ps after excitation. This vibrationally excited state relaxes within 20 ps at 188 K, while the bleaching band includes a long-lifetime component that lasts for more than 100 ps at 243 K. Thus, the OD (isotope-exchanged hydroxy groups) stretching band does not entirely recover in this period and is mirrored by an analogous weakening of the CH bending band of the adsorbed trans-2-butene. Simultaneously, three new bands in CH stretching region were observed at 3045, 3095, and 3130 cm(-1). This result suggests the presence of a short-lived intermediate formed by reaction between the acidic hydroxyl groups and adsorbed trans-2-butene.

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Section: Introductionmentioning

confidence: 99%

Direct Observation of Unstable Intermediate Species in the Reaction of trans-2-Butene on Ferrierite Zeolite by Picosecond Infrared Laser Spectroscopy

et al. 2005

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Host–Guest Interactions in Zeolites and Periodic Mesoporous Materials

Bein

2007

Studies in Surface Science and Catalysis

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Supramolecular Structure and Dynamics of Organic Molecules Adsorbed on the External Surface of MFI Zeolites. A Direct and Indirect Computational EPR Analysis

et al. 2001

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The nitroxides 1 and 1-oMe were employed as EPR probes for the investigation of the supramolecular structures and dynamics of organic molecules adsorbed on the external surfaces of two MFI zeolites (silicalite and ZSM-5). The results for the two zeolites are qualitatively similar, but depend quantitatively on the surface area of the external surface. Computational analysis of the EPR spectra as a function of loading of the probe is consistent with an initial strong association of the probes with the holes on the external surface, followed by a weaker binding to the framework of the external surface between the holes. The first supramolecular structure (binding to holes) fixes the motion of the probes and allows for an estimation of the average separation of the probes through EPR analysis of the dipole-dipole interaction. After saturation of the holes and the onset of the second supermolecular structure (binding to the framework), rapid diffusion of the probes on the framework occurs and provides a means for an estimation of the motion of the probe through EPR analysis of the spin-spin exchange interaction. The mobile framework's probes collide and displace the probes in the holes, resulting in a dynamic equilibrium between probes at both sites. The displacement of the nitroxides associated with the holes by three coadsorbed "displacer" molecules, 2, 3, and 4, was investigated by the change of the probe EPR. Addition of ketones 2 and 4 resulted in the displacement of nitroxides after sufficient displacer was added to saturate the holes on the external surface. This result is consistent with a stronger binding of the nitroxide to the surface and for the need for molecules of 2 and 4 to be situated on the framework before displacement of the nitroxide can occur. Compared to 2 and 4, 3 is found to be a poor displacer of nitroxide because of its weak association with the holes. From the competitive displacements, it is concluded that the binding to the external surface increases in the series 3 < 2 < 4 , 1, being at a minimum for the nonpolar 3 and a maximum for the nitroxide that possesses two polar moieties for interaction with the zeolite surface. On the basis of these results, a model was developed which described the supramolecular structures and dynamics formed by the ketones and MFI zeolites at a function of loading and for the various systems investigated.

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Dynamical studies of zeolitic protons and interactions with adsorbates by picosecond infrared spectroscopy

Cited by 4 publications

References 29 publications

Direct Observation of Unstable Intermediate Species in the Reaction of trans-2-Butene on Ferrierite Zeolite by Picosecond Infrared Laser Spectroscopy

Direct Observation of Unstable Intermediate Species in the Reaction of trans-2-Butene on Ferrierite Zeolite by Picosecond Infrared Laser Spectroscopy

Host–Guest Interactions in Zeolites and Periodic Mesoporous Materials

Supramolecular Structure and Dynamics of Organic Molecules Adsorbed on the External Surface of MFI Zeolites. A Direct and Indirect Computational EPR Analysis

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