caa a22 4500 475843681 CHVBK 20180406123907.0 cr unu---uuuuu 170329e20000401xx s 000 0 eng 10.1023/A:1027202604286 doi (NATIONALLICENCE)springer-10.1023/A:1027202604286 Hydrophobic titania-silica aerogels: epoxidation of cyclic compounds [Elektronische Daten] [C.A. Müller, R. Deck, T. Mallat, A. Baiker] Titania-silica mixed oxides with covalently bound methyl or phenyl groups were prepared from the corresponding alkyltrimethoxysilane and tetramethoxysilane using a sol-gel process and ensuing low-temperature supercritical extraction with CO2. Prehydrolysis of the organically modified silicon precursor was applied to compensate for their lower sol-gel reactivity compared to the precursors of the other constituents. Trihexylamine was used as a gelation catalyst. The dominantly mesoporous aerogels were characterized by thermal analysis, N2 adsorption, infrared spectroscopy, 29Si- and 13C-NMR spectroscopy, and transmission electron microscopy. Thermal analysis and 29Si MAS NMR measurements indicated covalent incorporation of the modifying group. 13C NMR spectra confirmed the integrity of the incorporated modifying groups. The materials were tested in the epoxidation of cyclohexene and cyclohexenol with tert-butylhydroperoxide. NH3 adsorption studied by DRIFT spectroscopy indicated no significant acidity of the aerogel surfaces, which was traced to the use of trihexylamine as gelation catalyst. Addition of zeolite 4 Å or NaHCO3 did not improve the performance of the unmodified and phenyl-modified aerogel, corroborating the suppressed acidity of the surface. Interestingly, the phenyl-modified aerogel was more selective in the epoxidation of cyclohexenol, when using polar solvents (ethanol or acetone), compared to the reaction in toluene. Kluwer Academic Publishers, 2000 titania-silica aerogel nationallicence epoxidation nationallicence organic modification nationallicence methyltrimethoxysilane nationallicence phenyltrimethoxysilane nationallicence cyclohexene nationallicence cyclohexenol nationallicence tert-butylhydroperoxide nationallicence Müller C.A. Laboratory of Technical Chemistry, Swiss Federal Institute of Technology, ETH Zentrum, CH-8092, Zürich, Switzerland E-mail: baiker@tech.chem.ethz.ch aut Deck R. Laboratory of Technical Chemistry, Swiss Federal Institute of Technology, ETH Zentrum, CH-8092, Zürich, Switzerland E-mail: baiker@tech.chem.ethz.ch aut Mallat T. Laboratory of Technical Chemistry, Swiss Federal Institute of Technology, ETH Zentrum, CH-8092, Zürich, Switzerland E-mail: baiker@tech.chem.ethz.ch aut Baiker A. Laboratory of Technical Chemistry, Swiss Federal Institute of Technology, ETH Zentrum, CH-8092, Zürich, Switzerland E-mail: baiker@tech.chem.ethz.ch aut Topics in Catalysis Kluwer Academic Publishers-Plenum Publishers 11-12/1-4(2000-04-01), 369-378 1022-5528 11-12:1-4<369 2000 11-12 11244 https://doi.org/10.1023/A:1027202604286 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1027202604286 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Müller C.A. Laboratory of Technical Chemistry, Swiss Federal Institute of Technology, ETH Zentrum, CH-8092, Zürich, Switzerland E-mail: baiker@tech.chem.ethz.ch aut NATIONALLICENCE 700 1- Deck R. Laboratory of Technical Chemistry, Swiss Federal Institute of Technology, ETH Zentrum, CH-8092, Zürich, Switzerland E-mail: baiker@tech.chem.ethz.ch aut NATIONALLICENCE 700 1- Mallat T. Laboratory of Technical Chemistry, Swiss Federal Institute of Technology, ETH Zentrum, CH-8092, Zürich, Switzerland E-mail: baiker@tech.chem.ethz.ch aut NATIONALLICENCE 700 1- Baiker A. Laboratory of Technical Chemistry, Swiss Federal Institute of Technology, ETH Zentrum, CH-8092, Zürich, Switzerland E-mail: baiker@tech.chem.ethz.ch aut NATIONALLICENCE 773 0- Topics in Catalysis Kluwer Academic Publishers-Plenum Publishers 11-12/1-4(2000-04-01), 369-378 1022-5528 11-12:1-4<369 2000 11-12 11244 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer