Physicochemical Characterization of Silicalite-1 Nanophase Material

• Published in: The journal of physical chemistry. B 1998-04, Vol.102 (15), p.2633-2639
• Main Authors: Ravishankar, Raman, Kirschhock, Christine, Schoeman, Brian J, Vanoppen, Peter, Grobet, Piet J, Storck, Sebastian, Maier, Wilhelm F, Martens, Johan. A, De Schryver, Frans C, Jacobs, Pierre A
• Format: Article
• Language: English
• Subjects: Chemical Technology; Kemisk teknologi
• ISSN: 1520-6106; 1520-5207; 1520-5207
• DOI: 10.1021/jp973147u

A silicalite-1 nanophase material with an elementary particle size of 18−100 nm is synthesized from clear solution and isolated and purified using supercentrifugation. The nanopowder is characterized in detail using scanning electron microscopy, high-resolution transmission electron microscopy, attenuated force microscopy, 29Si magic angle spinning NMR, 13C cross polarization magic angle spinning NMR, X-ray diffraction, dinitrogen physisorption, and thermogravimetric analysis and compared with micrometer-sized silicalite-1. The nanosized and micrometer-sized materials have many common properties including the refined structure and the nature and concentrations of tetrapropylammonium species incorporated during the synthesis. Unique properties of the nanophase are a splitting of the characteristic framework vibration at 550 cm-1 into a doublet at 555 and 570 cm-1, a high concentration of defect sites, and a strain in the crystallites along the “a” crystallographic direction. The nanophase exhibits a two-stage dinitrogen physisorption in the low-pressure region, ascribed to adsorptions in micropores created by the stacking of the nanoparticles in addition to adsorptions in the intracrystalline micropores.