The use of H2O2 over titanium-grafted mesoporous silica catalysts: a step further towards sustainable epoxidation

Matteo Guidotti; Claudio Pirovano; Nicoletta Ravasio; Beatriz Lázaro; José M. Fraile; José A. Mayoral; Bernard Coq; Anne Galarneau

doi:10.1039/B903302E

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The use of H₂O₂ over titanium-grafted mesoporous silica catalysts: a step further towards sustainable epoxidation†

Matteo Guidotti,*^a Claudio Pirovano,^a Nicoletta Ravasio,^a Beatriz Lázaro,^b José M. Fraile,^b José A. Mayoral,^b Bernard Coq^c and Anne Galarneau^c

Author affiliations

* Corresponding authors

^a CNR–Istituto di Scienze e Tecnologie Molecolari, IDECAT-CNR Unit, via Venezian 21, Milano, Italy
E-mail: m.guidotti@istm.cnr.it
Fax: +39 02 5031 4405
Tel: +39 02 5031 4428

^b Instituto de Ciencia de Materiales de Aragón, IDECAT-CSIC Unit, Fac. Ciencias, Zaragoza, Spain

^c Institut Charles Gerhardt Montpellier, UMR 5253 CNRS/UM2/ENSCM/UM1, ENSCM, 8 rue de l'Ecole Normale, Montpellier, France

Abstract

The epoxidation of cyclohexene with aqueous hydrogen peroxide over mesostructured Ti(Cp)₂Cl₂-grafted silica catalysts is described for the first time. Three kinds of Ti-containing systems with different textural properties have been employed: Ti/SiO₂, Ti/MCM-41 and Ti/MCM-48. A minimal local H₂O₂ concentration in the surroundings of Ti sites, obtained by a controlled dropwise addition of aqueous H₂O₂ (4.17 mmol H₂O₂ h⁻¹ g_cat⁻¹), is crucial for an effective and highly selective epoxidation. Excellent selectivity (>98%) in cyclohexene epoxide is obtained at the end of the slow H₂O₂ addition in acetonitrile. Higher yields in epoxide are found over Ti/MCM-48 than over Ti/MCM-41 or Ti/SiO₂ thanks to better isolation, dispersion and stability of Ti(IV) sites.

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Supplementary files

Nitrogen sorption isotherms and ¹³C-CP-MAS-NMR spectra of the catalysts PDF (311K)

Article information

DOI: https://doi.org/10.1039/B903302E
Article type: Paper
Submitted: 17 Feb 2009
Accepted: 12 Jun 2009
First published: 08 Jul 2009

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Green Chem., 2009,11, 1421-1427

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The use of H₂O₂ over titanium-grafted mesoporous silica catalysts: a step further towards sustainable epoxidation

M. Guidotti, C. Pirovano, N. Ravasio, B. Lázaro, J. M. Fraile, J. A. Mayoral, B. Coq and A. Galarneau, Green Chem., 2009, 11, 1421 DOI: 10.1039/B903302E

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