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High‐Zirconium‐Content Nano‐Sized Bimodal Mesoporous Silicas
Author(s) -
Ortiz de Zárate David,
GómezMoratalla Andrés,
Guillem Carmen,
Beltrán Aurelio,
Latorre Julio,
Beltrán Daniel,
Amorós Pedro
Publication year - 2006
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200501140
Subject(s) - mesoporous material , chemistry , chemical engineering , cationic polymerization , pulmonary surfactant , zirconium , bromide , mesoporous silica , adsorption , mesoporous organosilica , desorption , hydrolysis , organic chemistry , catalysis , biochemistry , engineering
Silica‐based nanoparticulated bimodal mesoporous materials with high Zr content (43 ≥ Si/Zr ≥ 4) have been synthesized by a one‐pot surfactant‐assisted procedure from a hydroalcoholic medium using a cationic surfactant (CTMABr = cetyltrimethylammonium bromide) as structure‐directing agent, and starting from molecular atrane complexes of Zr and Si as hydrolytic inorganic precursors. This preparative technique allows optimization of the dispersion of the Zr guest species in the silica walls. The bimodal mesoporous nature of the final high surface area nano‐sized materials is confirmed by XRD, TEM, and N 2 adsorption–desorption isotherms. The small intraparticle mesopore system (with pore sizes around 2–3 nm) is due to the supramolecular templating effect of the surfactant, while the large mesopores (around 12–24 nm) have their origin in the packing voids generated by aggregation of the primary nanometric mesoporous particles. The basicity of the reaction medium seems to be a key parameter in the definition of this last pore system. The effects induced by the progressive incorporation of Zr atoms on the mesostructure have been examined, and the local environment of the Zr sites in the framework has been investigated by UV/Vis spectroscopy. Observations based on the consequences of post‐treatments of the as‐synthesized materials with HCl/ethanol mixtures corroborate that the atrane method leads to Zr‐rich materials showing enhanced site accessibility and high chemical homogeneity throughout the pore walls. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)