Adsorption of oxygen molecule in NaA zeolite: Isotherms and infrared measurements

Soussen-Jacob, J.; Tsakiris, J.; Lara, E. Cohen de

doi:10.1063/1.456974

Cited by 23 publications

(19 citation statements)

References 19 publications

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“…Accordingly, we attempted to interpret the observed spectral shifts over zeolites in terms of the change in the donor strength of the framework and/or the electrostatic field strength (polarity) of the zeolite surface, since zeolites are akin to solid electrolytic solvents . In particular, the attempt to interpret the spectral shifts in terms of the latter is also pertinent, since the electrostatic field strengths in zeolites have been known to be extremely high and estimated to be in the order of 10 10 V m -1 in the vicinity of the cations. ,− Such extremely high electrostatic fields have even rendered the forbidden vibrational transitions of O 2 , , N 2 , and CH 4 86,87 to occur, upon adsorption of the molecules onto the cations, due to induced polarization.…”

Section: Discussionmentioning

confidence: 99%

Iodine as a Visible Probe for the Evaluation of Zeolite Donor Strength

et al. 1996

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The visible absorption band of iodine adsorbed on zeolite blue-shifted with increasing the electropositivity of the countercation and the aluminum content in the framework. This phenomenon was attributed to the increase in the donor strength of the zeolite framework based on the analogous spectral shift of iodine in solution. In support of this, a negative linear correlation was observed between the measured visible bands of iodine adsorbed on various zeolites and their calculated Sanderson's intermediate electronegativities. However, the simultaneous change in the electrostatic field strength within the zeolite pores, as a result of the change in the number and the size of the cation, has to be taken into account in order to interpret the overall spectral shifts more precisely. The iodine band sensitively blue-shifted with decreasing the moisture content in the framework but red-shifted with the loss of NH3 from NH4 +-exchanged zeolites. The visible band of iodine also progressively red-shifted with increasing the adsorbed amount, presumably due to the nature of iodine to deplete electron density from the framework. The framework structure also affected the spectral shift of the visible iodine band. The overall results established that iodine can be used as a novel molecular probe for the quantitative evaluation of the zeolite donor strength.

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Section: Discussionmentioning

confidence: 99%

Iodine as a Visible Probe for the Evaluation of Zeolite Donor Strength

et al. 1996

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“…32,42,[46][47][48][49][50] For instance, on the O 2 /Na-A system at 93 K two bands were observed at 1561.4 and 1553.5 cm À1 and assigned to the interaction of oxygen with two different Na 1 sites, where the adsorbed molecules are oriented in different way with respect to the electrical field generated by the cation. 51 A single n(OO) band at 1556 cm À1 was found upon adsorption of O 2 on Ca-A in the 213-123 K temperature interval 49 and on Na-A and Na-MOR zeolites at room temperature. 42 As far as the interaction with protonic sites is concerned, our data are in agreement with those of Wakabayashi et al 32 who attributed an absorption at 1550 cm À1 on the O 2 /H-Y system at 77 K to oxygen adsorbed on the protons of the (HF)OH groups located inside the supercage.…”

Section: Adsorption Of Omentioning

confidence: 97%

Vibrational and thermodynamic properties of Ar, N2, O2, H2 and CO adsorbed and condensed into (H,Na)-Y zeolite cages as studied by variable temperature IR spectroscopy

Грибов

Cocina

Spoto

et al. 2006

Phys. Chem. Chem. Phys.

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The adsorption of Ar, H2, O2, N2 and CO on (H,Na)-Y zeolite (Si/Al = 2.9, H+/Na+ approximately 5) has been studied at variable-temperature (90-20 K) and sub-atmospheric pressure (0-40 mbar) by FTIR spectroscopy. Unprecedented filling conditions of the zeolite cavities were attained, which allowed the investigation of very weakly adsorbed species and of condensed, liquid-like or solid-like, phases. Two pressure regimes were singled out, characterized by: (i) specific interaction at low pressure of the probe molecules (P) with the internal Brønsted and Lewis sites, and (ii) multilayer adsorption at higher pressure. In the case of CO the perturbation of the protonic sites located inside the sodalite cages was also observed. As the molecule is too large to penetrate the sodalite cage, the perturbation is thought to involve a proton jump tunneling mechanism. The adsorption energy for the (HF)OH...P (P = Ar, H2, O2, N2 and CO) specific interaction involving the high frequency Brønsted acid sites exposed in the supercages was derived following the VTIR (variable temperature infrared spectroscopy) method described by E. Garrone and C. Otero Areán (Chem. Soc. Rev., 2005, 34, 846).

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“…The basis of experimental evidence and extensive theoretical development, coupled with the modern implementation of "LSV" as SCV, has prompted detailed treatments of SCV and comparisons between SCV and LSV (1)(2)(3)(4)(5)(6)(7)(8)(9). One approach to the analysis of data relies on a convolution that transforms either result to a sigmoidal response, which is then analyzed (3, 4).…”

Section: Correspondencementioning

confidence: 99%

“…Static methods consist of near-equilibrium measurements of the extent of adsorption at specified, constent adsorbate concentrations. The extent of adsorption has been measured by methods including microbalance gravimetry (2), infrared absorption (3), and thermogravimetry (3)(4)(5). It was recognized very early that chromatography offered sig-nificant advantages in measurement speed when it could be used.…”

Section: Introductionmentioning

confidence: 99%

Determination of isotherms from chromatographic peak shapes

Dose¹,

Jacobson²,

Guiochon³

1991

Anal. Chem.

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A new method for determining equilibrium isotherms from chromatographic peak shapes Is presented. It differs from alternative methods like elution by characteristic point in that the present method accounts for the finite efficiency of real chromatographic columns, and so the new method Is used to Its best advantage in systems of low plate number. In the new method, Initial estimates of the parameters of an Isotherm equation are refined by finding simulated chromatographic peak shapes that most nearly approximate the experimental peak shapes. A series of example determinations demonstrate the method's utility.

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Adsorption of oxygen molecule in NaA zeolite: Isotherms and infrared measurements

Cited by 23 publications

References 19 publications

Iodine as a Visible Probe for the Evaluation of Zeolite Donor Strength

Iodine as a Visible Probe for the Evaluation of Zeolite Donor Strength

Vibrational and thermodynamic properties of Ar, N2, O2, H2 and CO adsorbed and condensed into (H,Na)-Y zeolite cages as studied by variable temperature IR spectroscopy

Determination of isotherms from chromatographic peak shapes

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