The physical properties (microcrystal morphology, crystallinity, internal perfection, adsorptive capacities toward CO and N2, and IR manifestations of the skeletal modes and of the hydroxyl groups) of a Na- and Al-free silicalite (S) prepared following a specifically designed method are investigated. Comparison is made with the silicalite containing Na and Al impurities prepared following a more conventional (classical) path (SNa). The experimental techniques are X-ray diffraction (XRD), high-resolution electron microscopy (HRTEM), infrared spectroscopy in reflectance mode (FTIR), and volumetric isotherms in a BET apparatus. The most relevant results are as follows: (i) S microcrystals have very regular octagonal prismatic habit, (ii) nanodefects and microcavites are more aboundant in S than in SNa, (iii) hydroxyl groups are present at the internal defects sites, and (iv) N2 and CO volumetric isotherms at 77 K differ from S and SNa.
Silicalite Characterization .1. Structure, Adsorptive Capacity, and IR Spectroscopy of the Framework and Hydroxyl Modes
ZECCHINA, Adriano;BORDIGA, Silvia;SPOTO, Giuseppe;
1992-01-01
Abstract
The physical properties (microcrystal morphology, crystallinity, internal perfection, adsorptive capacities toward CO and N2, and IR manifestations of the skeletal modes and of the hydroxyl groups) of a Na- and Al-free silicalite (S) prepared following a specifically designed method are investigated. Comparison is made with the silicalite containing Na and Al impurities prepared following a more conventional (classical) path (SNa). The experimental techniques are X-ray diffraction (XRD), high-resolution electron microscopy (HRTEM), infrared spectroscopy in reflectance mode (FTIR), and volumetric isotherms in a BET apparatus. The most relevant results are as follows: (i) S microcrystals have very regular octagonal prismatic habit, (ii) nanodefects and microcavites are more aboundant in S than in SNa, (iii) hydroxyl groups are present at the internal defects sites, and (iv) N2 and CO volumetric isotherms at 77 K differ from S and SNa.File | Dimensione | Formato | |
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JPhysChem_1992_96_4985.pdf
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