The possible use of Gamma-functions for the determination of microporosity-mesoporosity and the pore size in materials with ordered (MCM) and quasi-ordered pore structure

 
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The possible use of Gamma-functions for the determination of microporosity-mesoporosity and the pore size in materials with ordered (MCM) and quasi-ordered pore structure (EN)

Armatas, G. S. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Armatas, G. S. (EN)

The purpose of this work is to examine the possibility to apply Gamma-functions for the description of pore size distribution (PSD) as well as for the distinction between the microporosity and mesoporosity in materials with ordered and/or quasi-ordered pore structure. The group of materials used were six (6) MCM-Al-x solids (x = 0, 5, 10, 15, 20, 50) in which the ordered mesoporosity (x = 0) was gradually destroyed by increasing the percentage substitution x of Si by Al. All samples were characterized by N-2 adsorption-desorption porosimetry. Then the estimation of PSD took place by using two Gamma-functions, one for the micropore region (0 < D-P < 2 nm) and another for the mesopore region (2 < D-p < 50 nm). As a benchmark for the choice of Gamma-functions their fitting to the N-2-adsorption loop was used. Consequently the PSD from those chosen Gamma-functions was calculated and the results were compared with the method of Horvath-Kawazoe (HK). The specific surface areas S-p, the specific pore volumes V-p and the maximum D-P of the PSDs calculated by the standard methodologies (HK and BET) are perfectly compared to the ones obtained with the methodology of Gamma-functions. In addition the use of Gamma-functions methodology provides the possibility to distinguish the percentage of microporosity in such quasi-ordered, amorphous mesoporous, or quasi-mesoporous, materials which is zero for the pure siliceous MCM-Al-0 but increases gradually with the addition of Al atoms and reaches similar to32% for the highly substituted solids MCM-Al-50. (C) 2003 Elsevier Inc. All rights reserved. (EN)

porous solids (EN)

Πανεπιστήμιο Ιωαννίνων (EL)
University of Ioannina (EN)

Microporous and Mesoporous Materials (EN)

Αγγλική γλώσσα

2004

<Go to ISI>://000188643100007

Elsevier (EN)



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