Complexos Níquel-β-diiminas heterogeneizados em MCM-41 e SBA-15: aplicação em oligomerização de olefinas

Abstract

The β-diimine ligands 2-(phenyl)amine-4-(phenyl)imine-2-pentene and 2-(2,6- dimethylphenyl)amine-4-(2,6-dimethylphenyl)imine-2-pentene were combined with the alkoxysilane group chloropropyltrimethoxysilane (CPTMS) and covalently anchored to a mesoporous MCM-41, Al-MCM-41 and SBA-15 support, ordered by interaction with the silanols of the silica matrix and complexed with nickel. The complexes were synthesized for application in ethylene and propylene oligomerization and for comparing results between homogeneous and heterogeneous systems. The support is first synthesized, calcined, anchored to the ligand, and then subsequent complexation of nickel is realized. These materials were characterized by several techniques such as 1H, 13C and 29Si NMR, small angle XRD, Infra-red, thermogravimetric analysis, nitrogen adsorption-desorption isotherms, transmission and scanning electron microscopy, elemental analysis, and flame atomic absorption spectroscopy, to confirm the success of the synthesis. Both homogeneous and heterogeneous complexes are active and selective for the reactions of ethylene and propylene oligomerization. The heterogenized materials were less active than the homogeneous analogous complexes in the reactions of oligomerization of ethylene, however, were more selective for both C4 fractions and for α-C4. In reactions with propylene, the homogeneous complexes promoted the dimerization reaction and the heterogenized complexes the alkylation reaction of toluene with propylene complex.Complexes were tested in recycle reactions proved to be efficient for use in large scale.