Binuclear furanyl-azine metal complexes encapsulated in NaY zeolite as efficiently heterogeneous catalysts for phenol hydroxylation.

Two different methods A and B were used for preparing binuclear furanyl-azine metal complexes encapsulated in NaY zeolite. These new heterogeneous catalysts based on Fe(II) or Cu(II) complexes with a metal/ligand molar ratio of 2:1, were characterized by different spectroscopic techniques and chemical analysis which confirm the presence of the metal complexes inside the supercages of the zeolite. Mössbauer spectroscopy technique analysis confirms the presence of the Fe3+- complexes in octahedral coordination. The new heterogeneous catalysts were catalytic evaluated by phenol hydroxylation and compared with the encapsulated metal furanyl-azine complexes in NaY zeolite. The zeolite themselves do not present any activity and the presence of the metal complexes improve their activity. All heterogeneous catalysts enhance higher conversion of phenol to catechol. Image 1 • Binuclear furanyl-azine metal complexes were successfully encapsulated in NaY zeolite. • Characterization techniques confirm the presence of the metal complexes inside the supercages of the zeolite. • All the heterogeneous catalysts are active in phenol hydroxylation. • The phenol conversion under heterogeneous conditions is close to that obtained for homogeneous counerparts [ABSTRACT FROM AUTHOR]