Issue 32, 2013

Niobium–silica catalysts for the selective epoxidation of cyclic alkenes: the generation of the active site by grafting niobocene dichloride

Abstract

Niobium-containing silica materials obtained by deposition via liquid-phase grafting or dry impregnation of niobocene(IV) dichloride are active and selective catalysts in the epoxidation of alkenes in the presence of aqueous hydrogen peroxide. The generation of the catalytically-active Nb species was followed step-by-step, and investigated using a combined DR-UV-Vis, NIR, Raman, XRD, XANES and EXAFS analyses. At the end of the grafting procedure, the nature of the surface active species can be described as an oxo-Nb(V) site, tripodally grafted onto the silica surface in close proximity to other Nb(V) centres. The liquid-phase methodology provides a better dispersion of the metal sites onto the siliceous support than the dry-impregnation approach. The niobium–silica catalysts were then tested in the epoxidation of cyclohexene and 1-methylcyclohexene, as model substrates.

Graphical abstract: Niobium–silica catalysts for the selective epoxidation of cyclic alkenes: the generation of the active site by grafting niobocene dichloride

Article information

Article type
Paper
Submitted
12 Apr 2013
Accepted
01 Jul 2013
First published
02 Jul 2013

Phys. Chem. Chem. Phys., 2013,15, 13354-13362

Niobium–silica catalysts for the selective epoxidation of cyclic alkenes: the generation of the active site by grafting niobocene dichloride

C. Tiozzo, C. Bisio, F. Carniato, A. Gallo, S. L. Scott, R. Psaro and M. Guidotti, Phys. Chem. Chem. Phys., 2013, 15, 13354 DOI: 10.1039/C3CP51570B

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