abstract
A novel method to prepare silica nano-sized particles incorporating polyoxometalates was developed leading to a new efficient heterogeneous oxidative catalyst. Zinc-substituted polyoxotungstate [PW11Zn-( H2O)O-39](5-) (PW11Zn) was encapsulated into silica nanoparticles using a cross-linked organic-inorganic core, performed through successive spontaneous reactions in water. The potassium salt of PW11Zn and the composite formed, PW11Zn-APTES@SiO2, were characterized by a myriad of solid-state methods such as FT-IR, FT-Raman, P-31 and C-13 CP/MAS solid-state NMR, elemental analysis and SEM-EDS, confirming the integrity of the PW11Zn structure immobilized in the silica nanoparticles. The new composite has shown to be a versatile catalyst for the oxidation of olefins and also to catalyze the desulfurization of a model oil using H2O2 as the oxidant and acetonitrile as the solvent. The novel composite material was capable of being recycled without significant loss of activity and maintaining its structural stability for consecutive desulfurization and olefin oxidative cycles.
keywords
LIQUID-PHASE OXIDATION; SELECTIVE OXIDATION; HETEROGENEOUS CATALYSTS; MESOPOROUS SILICA; HYDROGEN-PEROXIDE; CATIONIC SILICA; SUBSTITUTED POLYOXOMETALATE; HIGHLY EFFICIENT; HYBRID SILICA; KEGGIN UNITS
subject category
Chemistry
authors
Nogueira, LS; Ribeiro, S; Granadeiro, CM; Pereira, E; Feio, G; Cunha-Silva, L; Balula, SS
our authors
Carlos Miguel Cardeal Enes Granadeiro
Post-Doc Fellowship
Lucie Solange Nogueira
PhD Studentacknowledgements
The authors acknowledge the Fundacao para a Ciencia e a Tecnologia (FCT, MEC, Portugal) for their general financial support through the strategic projects Pest-C/EQB/LA0006/2011 (to Associated Laboratory REQUIMTE) and PEst-C/CTM/LA0025/2022 (Strategic Project - LA 25-2001/2012), the R&D project PTDC/EQU-EQU/121677/2010, the fellowship SFRH/BPD/73191/2010 (to CG), the Portuguese Nuclear Magnetic Resonance Network (PRNMR) and the research group of Dr Isabel Goncalves from CICECO Laboratory, University of Aveiro, Portugal.