Encaged Cu2+/Co2+ zeolite materials: Efficient and reusable catalysts for oxidation of phenol

Abstract

This work aims to use the extra-ordinary properties inherent to zeolite Y in facilitating the construction of a novel supra-molecular assembly by encaging transition metal complexes into the zeolite pores and then utilizing these assembled materials as novel catalysts as a heterogeneously behaved homogeneous catalytic system. Copper (II) and cobalt (II) complexes of N, N-Dihydroxy-2,3-butanediimine (DBD) were encaged in the cages of zeolite-Y by flexible ligand synthesis method. Both encaged materials including their precursors Na–Y, Cu–Y, and Co–Y are characterized for their analytical, textural, spectral, and morphological properties. Based on physicochemical, spectral, and morphological characterization, it is established that the metal complexes have been successfully encaged inside zeolite Y pores. All the catalysts including their precursors and free metal complexes have been screened for catalyzing the oxidation of phenol using H2O2 as an oxidant. Performing several sets of experiments, reaction parameters have been optimized to obtain the maximum conversion of phenol. The blank reaction was also carried out under similar optimized conditions. All the prepared materials exhibited catalytic activity towards the oxidation of phenol. The zeolite encaged transition metal complexes, Co-(DBD)2-Y and Cu-(DBD)2-Y also proved to have good potential recyclability and can be used without a loss in the activity.