Preparation of crystal-like periodic mesoporous phenylene-silica derivatized with ferrocene and its use as a catalyst for the oxidation of styrene

authors	Gomes, AC; Ferreira, MJ; Bruno, SM; Bion, N; Ferreira, P; Valente, AA; Pillinger, M; Rocha, J; Goncalves, IS
nationality	International
journal	DALTON TRANSACTIONS
keywords	MOLECULAR-SCALE PERIODICITY; BENZENE-SILICA; HETEROGENEOUS CATALYST; SELECTIVE OXIDATION; HYBRID MATERIAL; AQUEOUS-MEDIUM; ORGANIC GROUPS; CHANNEL WALLS; PORE WALLS; ORGANOSILICAS
abstract	The surface silanol groups in crystal-like mesoporous phenylene-silica have been derivatized with trimethylsilyl, benzyldimethylsilyl and dimethylsilyl(ferrocene) groups by performing a post-synthetic grafting reaction with the corresponding chlorosilane precursors. The success of the grafting procedure was demonstrated by transmission FT-IR spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and C-13 and Si-29 magic-angle spinning (MAS) NMR spectroscopy. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N-2 adsorption data for the modified materials indicated preservation of the mesostructure as well as the molecular-scale periodicity in the pore walls. Ferrocene and the ferrocenyl-modified periodic mesoporous organosilica (PMO) were employed in the catalytic oxidation of styrene at 55 degrees C using either hydrogen peroxide or tert-butylhydroperoxide as an oxidant. The main reaction product was always benzaldehyde (BzCHO), and other products included styrene oxide, benzoic acid and 2-hydroxyacetophenone. Using a styrene : H2O2 molar ratio of 1 : 5, the highest BzCHO yields at 24 h were 65% (85% selectivity) for ferrocene (semibatch conditions involving stepwise addition of H2O2, 1 mol% Fe) and 34% (83% selectivity) for the modified PMO (batch conditions, 0.06 mol% Fe). The modified PMO could be recovered and reused, albeit with a drop in catalytic activity due to partial metal leaching during the first catalytic run.
publisher	ROYAL SOC CHEMISTRY
issn	1477-9226
year published	2013
volume	42
issue	40
beginning page	14612
ending page	14620
digital object identifier (doi)	10.1039/c3dt51931g
web of science category	Chemistry, Inorganic & Nuclear
subject category	Chemistry
unique article identifier	WOS:000324931400032