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Keywords:

  • Heterogeneous catalysis;
  • Zeolites;
  • Copper;
  • Oxidation;
  • Schiff bases

Abstract

The oxidation of phenol, cychohexanol and hydroquinone has been screened in the presence of copper(II) complexes with the Schiff-base salen ligand, 1,5-bis[(E)-5-chloro-2-hydroxybenzylideneamino]-1H-imidazole-4-carbonitrile, and encapsulated into NaY zeolite by using two different methods. The new heterogeneous catalysts were characterized by SEM, XRD, FTIR, EPR and Raman spectroscopy as well as by chemical analysis. The structures of the copper(II) complexes were proposed on the basis of theoretical studies (DFT). The catalytic activities of the encapsulated copper(II) complexes in NaY were compared with their homogeneous counterparts. The results show higher or similar substrate conversion when compared with the free complex in all the reactions tested. After their use in catalytic reaction, these catalysts were found to be reusable without loss of activity.