The Ti is in tetrahedral coordination in vacuo and expands its coordination sphere upon interaction with adsorbates. In the presence of H2O and H2O/H2O2 solutions one of the SiOTi bridges is hydrolyzed with formation of (=SiO)(3)L(2)TiOH (L = H2O) and (=SiO)(3)L(2)TiOOH species, respectively. When NH3 is dosed on (=SiO)(3)L(2)TiOOH structures (=SiO)(3)L(2)TiOO(-)NH(4)(+) species are formed. These species are thought to play an important role in the ammoximation reaction. The geometries of the peroxidic species (open or bridged) are discussed also on the basis of ab initio calculations.

Structural characterization of Ti centres in Ti-silicalite and reaction mechanisms in cyclohexanone ammoximation

ZECCHINA, Adriano;BORDIGA, Silvia;LAMBERTI, Carlo;RICCHIARDI, Gabriele;SCARANO, Domenica;
1996-01-01

Abstract

The Ti is in tetrahedral coordination in vacuo and expands its coordination sphere upon interaction with adsorbates. In the presence of H2O and H2O/H2O2 solutions one of the SiOTi bridges is hydrolyzed with formation of (=SiO)(3)L(2)TiOH (L = H2O) and (=SiO)(3)L(2)TiOOH species, respectively. When NH3 is dosed on (=SiO)(3)L(2)TiOOH structures (=SiO)(3)L(2)TiOO(-)NH(4)(+) species are formed. These species are thought to play an important role in the ammoximation reaction. The geometries of the peroxidic species (open or bridged) are discussed also on the basis of ab initio calculations.
1996
Inglese
Nessuno
32
97
106
10
structural characterization; Ti centres; Ti-silicalite; reaction mechanisms; selective oxidation; ab ibnitio calculations; Raman; ammoximation reaction; hydrogen peroxide
ITALIA
262
10
A. Zecchina;S. Bordiga;C. Lamberti;G. Ricchiardi;C. Lamberti;G. Ricchiardi;D. Scarano;G. Petrini;G. Leofanti;M. Mantegazza
info:eu-repo/semantics/article
none
03-CONTRIBUTO IN RIVISTA::03A-Articolo su Rivista
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/144418
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