Differential scanning calorimetry leads to high precision for water in zeolites determined by thermogravimetry

Aboul-Gheit, Ahmed K.; Al-Hajjaji, M.A.; Summan, A.M.; Abdel‐Hamid, S. M.

doi:10.1016/0040-6031(88)87285-x

Cited by 15 publications

(2 citation statements)

References 3 publications

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“…The TGA of crystalline fluorenone exhibits a fast desorption step at 270 °C. Figure 4 shows the DSC for both zeolite L and fluorenone/zeolite L. The zeolite L sample shows a sharp endothermic transition around 270 °C, which can be attributed to water desorption from the zeolite 18. 19 This transition shifts to 250 °C in the case of the fluorenone/zeolite L material.…”

Section: Resultsmentioning

confidence: 99%

Electronic and Vibrational Properties of Fluorenone in the Channels of Zeolite L

Devaux

Minkowski

Calzaferri

2004

Chemistry A European J

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Fluorenone (C13H8O) was inserted into the channels of zeolite L by using gas-phase adsorption. The size, structure, and stability of fluorenone are well suited for studying host-guest interactions. The Fourier transform IR, Raman, luminescence, and excitation spectra, in addition to thermal analysis data, of fluorenone in solution and fluorenone/zeolite L are reported. Normal coordinate analysis of fluorenone was performed, based on which IR and Raman bands were assigned, and an experimental force field was determined. The vibrational spectra can be used for nondestructive quantitative analysis by comparing a characteristic dye band with a zeolite band that has been chosen as the internal standard. Molecular orbital calculations were performed to gain a better understanding of the electronic structure of the system and to support the interpretation of the electronic absorption and luminescence spectra. Fluorenone shows unusual luminescence behavior in that it emits from two states. The relative intensity of these two bands depends strongly on the environment and changes unexpectedly in response to temperature. In fluorenone/zeolite L, the intensity of the 300 nm band (lifetime 9 micros) increases with decreasing temperature, while the opposite is true for the 400 nm band (lifetime 115 micros). A model of the host-guest interaction is derived from the experimental results and calculations: the dye molecule sits close to the channel walls with the carbonyl group pointing to an Al3+ site of the zeolite framework. A secondary interaction was observed between the fluorenone's aromatic ring and the zeolite's charge-compensating cations.

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Section: Resultsmentioning

confidence: 99%

Electronic and Vibrational Properties of Fluorenone in the Channels of Zeolite L

Devaux

Minkowski

Calzaferri

2004

Chemistry A European J

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“…About 75% of the total weight loss occurs from 0 and 250°C due to removal of the water of hydration [30,41,42]. Fig.…”

Section: Thermal Degradation Of Zeolitesmentioning

confidence: 99%

Gas adsorption properties of ZSM-5 zeolites heated to extreme temperatures

Pérez-Page

Makel

Guan

et al. 2016

Ceramics International

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a b s t r a c tZeolites are broadly useful catalysts and molecular sieve adsorbents for purification. In this work the thermal degradations of bare and platinum-loaded ZSM-5 was studied with the goal of understanding the behavior of nanoporous solids at extreme temperatures comparable to those present in nuclear fuels. Zeolites were heated in air and nitrogen at temperatures up to 1500°C, and then characterized for thermal stability via X-ray diffraction (XRD) and for gas adsorption by the Brunauer-Emmett-Teller (BET) method. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were also employed. These results indicate zeolites are stable when heattreated up to 800°C and degrade slowly at higher temperatures. However, significant surface area degradation begins at 1025-1150°C with an activation energy of 400 kJ/mole. At 1500°C, gas adsorption measurements and SEM images show complete collapse of the porous structure. Critically for nuclear fuel applications, however, the zeolites still adsorb helium in significant quantities.

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Acid site strength distribution in mordenites by differential scanning calorimetry

Aboul-Gheit

1988

Journal of Catalysis

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Differential scanning calorimetry leads to high precision for water in zeolites determined by thermogravimetry

Cited by 15 publications

References 3 publications

Electronic and Vibrational Properties of Fluorenone in the Channels of Zeolite L

Electronic and Vibrational Properties of Fluorenone in the Channels of Zeolite L

Gas adsorption properties of ZSM-5 zeolites heated to extreme temperatures

Acid site strength distribution in mordenites by differential scanning calorimetry

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