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Molecular sieve supported transition metal complexes

The project concerns the preparation, characterization and study of the catalytic properties of zeolites and activated carbons with immobilized and anchored first-row late transition metal complexes with polydentate ligands containing several co-ordination spheres, obtained by Schiff condensation of aldehydes and B-diketones with diamines.

Copper(II), cobalt(II) and nickel(II) complexes with Schiff base ligands derived from acetylacetone, salicylaldehyde and naphthaldehyde can be encapsulated in the supercages of zeolite sodium yttrium by the three procedures: in situ Schiff condensation between pre-adsorbed copper complexes and the corresponding polyamines; diffusion of the ligands into the zeolite through the pores, where upon coordination with the intrazeolite metal ion they form complexes too large to exit; and in situ ligand condensation, template synthesis. Surface, thermal and spectroscopic characterization of the new materials indicate that the encapsulated complexes do not experience extensive distortions in the supercage and that chemical ligation to the zeolitic surface should be minimal. The cobalt(II) based catalysts exhibit high catalytic efficiency in the oxidation of hydroquinone and cyclohexene by molecular oxygen under liquid-phase conditions. Porous carbon materials have been prepared with adequate texture and surface chemistry to be used for anchoring functionalized metal complexes. Different activation procedures and post-treatments were used. Supports were characterized by temperature programmed desorption (TPD), Fourier transform infrared (FTIR) and adsorption measurements. Modified active carbons were able to bind covalently several model molecules (phenylenediamine, cyannuric chloride and substituted tetrazoles) and complexes.

Reported by

Universidade do Porto
Rua dos Bragas
4099 Porto
Portugal
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