- Email: [email protected]
06-P-12 - Synthesis and characterization of highly ordered chromium-substituted MCM-48 materials with tailored pore sizes
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06-P-11 - The synthesis and hydrothermal stability of directly usable hexagonal mesoporous silica by efficient primary amine template extraction in acidified water K. Cassiers, P. Van Der Voort and E.F. Vansant
Dept. of Chemistry- Laboratory of Adsorption and Catalysis, University of Antwerp (U.I.A.), Universiteitsplein 1, B-2610 Wilrij'k, Belgium, e-mail: [email protected] High quality HMS was repeatedly and reproducibly prepared by a novel extraction procedure to remove the primary amine template using acidified water. This very efficient extraction (100%) does not affect the physical properties of the resulting mesostructure. Compared to the ethanol-extracted HMS, no subsequent calcination step is required to remove the surface ethoxy groups produced during the ethanol extraction. Moreover, the recovered surfactant can be easily re-used in a fresh synthesis. Furthermore, an improved hydrothermal stability was observed after using the acidified water extraction procedure.
06-P-12 - Synthesis and characterization of highly ordered chromiumsubstituted MCM-48 materials with tailored pore sizes C. Pak and G.L. Hailer
Department of Chemical Engineering, Yale University, P.O. Box 208286, New Haven, CT 06520-8286, USA Cr-substituted MCM-48 materials have been prepared by a direct hydrothermal procedure using mixtures of cationic alkyltrimethylammonium surfactant with different alkyl chain length and neutral surfactants. At least eight X-ray diffraction peaks corresponding to the cubic Ia3d structure and high surface areas were observed for all the samples, which indicates that the Cr containing materials have a highly ordered MCM-48 structure. Average pore size of Cr-MCM-48 samples was increased from 3.2 to 3.9 nm with increasing alkyl chain from 14 to 18 carbons. It is suggested from an intense pre-edge peak in the XANES that the Cr in the MCM-48 structure has tetrahedral coordination. -
06-P-13 - Preparation and characterization of mesoporous silica spheres R. Van Grieken, D.P. Serrano, C. Martos and A.M. Melgares
ESCET. Universidad Rey Juan Carlos, c/Tulipdn s/n, 28933 M6stoles, Madrid, Spain. e-mail: r. vangrieken@escet, urjc. es The effect of different variables in the preparation of mesoporous silica spheres has been investigated through a two-phase method that requires tetrabutoxy silane as silica source, cetyltrimethylammonium chloride as surfactant, and water as solvent. The materials synthesized show regular pores with sizes around 2.0 nm, BET surface areas larger than 1000 m2/g and a narrow spherical particle size distribution. These textural properties are achieved through the surfactant removal by a mild calcination procedure, otherwise the porous structure is partially destroyed. The size of the silica spheres so obtained can be controlled in the range 300-700 pm through different variables, mainly by varying the stirring speed of the two-phase solution.
06-P-11 - The synthesis and hydrothermal stability of directly usable hexagonal mesoporous silica by efficient primary amine template extraction in acidified water K. Cassiers, P. Van Der Voort and E.F. Vansant
Dept. of Chemistry- Laboratory of Adsorption and Catalysis, University of Antwerp (U.I.A.), Universiteitsplein 1, B-2610 Wilrij'k, Belgium, e-mail: [email protected] High quality HMS was repeatedly and reproducibly prepared by a novel extraction procedure to remove the primary amine template using acidified water. This very efficient extraction (100%) does not affect the physical properties of the resulting mesostructure. Compared to the ethanol-extracted HMS, no subsequent calcination step is required to remove the surface ethoxy groups produced during the ethanol extraction. Moreover, the recovered surfactant can be easily re-used in a fresh synthesis. Furthermore, an improved hydrothermal stability was observed after using the acidified water extraction procedure.
06-P-12 - Synthesis and characterization of highly ordered chromiumsubstituted MCM-48 materials with tailored pore sizes C. Pak and G.L. Hailer
Department of Chemical Engineering, Yale University, P.O. Box 208286, New Haven, CT 06520-8286, USA Cr-substituted MCM-48 materials have been prepared by a direct hydrothermal procedure using mixtures of cationic alkyltrimethylammonium surfactant with different alkyl chain length and neutral surfactants. At least eight X-ray diffraction peaks corresponding to the cubic Ia3d structure and high surface areas were observed for all the samples, which indicates that the Cr containing materials have a highly ordered MCM-48 structure. Average pore size of Cr-MCM-48 samples was increased from 3.2 to 3.9 nm with increasing alkyl chain from 14 to 18 carbons. It is suggested from an intense pre-edge peak in the XANES that the Cr in the MCM-48 structure has tetrahedral coordination. -
06-P-13 - Preparation and characterization of mesoporous silica spheres R. Van Grieken, D.P. Serrano, C. Martos and A.M. Melgares
ESCET. Universidad Rey Juan Carlos, c/Tulipdn s/n, 28933 M6stoles, Madrid, Spain. e-mail: r. vangrieken@escet, urjc. es The effect of different variables in the preparation of mesoporous silica spheres has been investigated through a two-phase method that requires tetrabutoxy silane as silica source, cetyltrimethylammonium chloride as surfactant, and water as solvent. The materials synthesized show regular pores with sizes around 2.0 nm, BET surface areas larger than 1000 m2/g and a narrow spherical particle size distribution. These textural properties are achieved through the surfactant removal by a mild calcination procedure, otherwise the porous structure is partially destroyed. The size of the silica spheres so obtained can be controlled in the range 300-700 pm through different variables, mainly by varying the stirring speed of the two-phase solution.