resumo
Silica nanoparticles supporting polyoxometalates (POMs), namely an iron(III) mono-substituted Keggin-type polyoxotungstate of formula alpha-[PW(11)Fe(III)(H(2)O)O(39)](4-) and a sandwich-type tungstophosphate with the formula B-alpha-[(PW(9)O(34))(2)Fe(4)(III)(H(2)O)(2)](6-) were synthesized. The POM/SiO(2) nanocomposites were obtained by alkaline hydrolysis of tetraethoxysilane using a reverse micelle and sol-gel technique. The spectroscopic studies suggest that the POMs were successfully immobilized on the silica nanoparticles. The catalytic activity of POM/SiO(2) nanomaterials was tested in the epoxidation of geraniol using H(2)O(2) as oxygen donor. The alpha-[PW(11)Fe(III)(H(2)O)O(39)](4-)/SiO(2) nanocomposite was the most efficient catalyst with high geraniol conversion and good regioselectivity for 2,3-epoxygeraniol. (C) 2010 Elsevier B.V. All rights reserved.
palavras-chave
IRON-SUBSTITUTED POLYOXOTUNGSTATES; HYDROGEN-PEROXIDE; CATIONIC SILICA; POLYOXOMETALATE CLUSTERS; AEROBIC OXIDATIONS; ALLYLIC ALCOHOLS; AMORPHOUS SILICA; EPOXIDATION; CHEMISTRY; H2O2
categoria
Chemistry
autores
Sousa, JLC; Santos, ICMS; Simoes, MMQ; Cavaleiro, JAS; Nogueira, HIS; Cavaleiro, AMV
nossos autores
Ana Maria Vieira Silva Viana Cavaleiro
Professor Catedrático
Helena Isabel Seguro Nogueira
Professor Auxiliar com Agregação
Isabel Cristina Maia da Silva Santos Vieira
Investigador Júnior
Joana Lia Cardoso de Sousa
Bolseiro de pós-Doutoramentoagradecimentos
Thanks are due to the University of Aveiro and FCT/FEDER for funding CICECO and QOPNA.