Studies on mesoporous niobosilicates synthesized using F127 triblock copolymer
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Studies on mesoporous niobosilicates synthesized using F127 triblock copolymer Agnieszka Feliczak-Guzik · Agata Wawrzynczak · Izabela Nowak
Published online: 17 April 2009 © Springer Science+Business Media, LLC 2009
Abstract A detailed characterization of cage-like mesoporous SBA-16 niobosilicate with tailored features of the structure is reported. The materials were synthesized in a EO106 PO70 EO106 (F127)-water system under acidic conditions and the pore diameters were tuned by varying the hydrothermal treatment temperature and time. The effects of the synthesis parameters on the structural/textural properties of the cubic Im3m niobosilicates have been investigated systematically. We show that the total pore volume, pore diameter, and micro-/mesopores ratio can be controlled very efficiently by changing the synthesis parameters. Keywords NbSBA-16 · Cage-like structure · Characterization · Structural/textural properties · Niobium source
1 Introduction The discovery of supramolecular(surfactant)-templated ordered mesoporous materials (OMMs) provides an extension of ordered microporous structures of zeolites and zeotypes into the mesopore range. Initially discovered MCM-41 and MCM-48 (Kresge et al. 1992) as well as many other important ordered mesoporous materials, such as HMS, KIT1, SBA-3, and SBA-15 exhibit channel-like pore structures (e.g., Bagshaw et al. 1995). The succeeding discovery of
Honoring Professor Mietek Jaroniec, on the occasion of his 60th birthday. A. Feliczak-Guzik · A. Wawrzynczak · I. Nowak () Adam Mickiewicz University, Faculty of Chemistry, Grunwaldzka 6, 60-780 Poznan, Poland e-mail: [email protected]
ordered silica with cage-like mesoporous structures is a further major achievement and breakthrough in the synthesis of mesoporous materials (e.g., Zhao et al. 1998a; Huo et al. 1994). Many efforts have been taken to characterize their cavity connection, as well as tailor their structures for various applications. The use of commercially available surfactants of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) EOX POy EOX type, i.e., inexpensive and environmentally friendly nonionic triblock copolymer in the formation of mesoporous materials was reported (Zhao et al. 1998b) in the late 1990s. The synthesis carried out with these surfactants usually occurs in very low pH (pH 2) solutions where the interaction proceeds through an S0 H+ X− I+ mechanism (S0 H+ being the surfactant in interaction with a hydronium ion, X− the chloride ion and I+ the protonated silica). This results in SBA- and FDU-type materials. Among polymer-templated OMMs with channel-like (SBA-3, -12, -15) and cage-like (SBA-1, -6, -16 and FDU-1) mesopores, the cage-like materials become especially popular because of their attractive 3-dimensional mesoporous structures, which facilitate mass transfer and are less prone for pore blockage. These features of cage-like materials make them attractive for adsorption, catalysis and separations as well as for immobilization of biomolecules, sensors and catalysts
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