Magneto-structural properties and reliability of (Mn/Ni/Zn) substituted cobalt-copper ferrite heterogeneous catalyst for selective and efficient oxidation of aryl alcohols

Abstract

Herein, M²⁺ substituted CoCuFe₂O₄ (M²⁺ = Mn, Zn, Ni) ferrites have been synthesized using the sol-gel auto combustion method. The structural, morphological and magnetic studies confirm the phase formation of pure magnetic cubic spinel MCoCuFe₂O₄ (M²⁺ = Mn, Zn, Ni) ferrites. The substitution with Mn, Ni and Zn does not show large variation in binding energies obtained from XPS of Cu (2p) that specifies identical copper concentration (Cu_0.5) and substitution of only cobalt (Co²⁺) in Mn-F, Ni-F and Zn-F catalysts. Interestingly, MCoCuFe₂O₄ magnetic catalysts were explored for selective oxidation of a series of substituted benzyl alcohols. Catalyst Mn-F showed 93% conversion of benzyl alcohol while, Ni-F showed 95% conversion of 4-nitrobenzyl alcohol. Whereas, the catalyst Zn-F was showed 96% conversion for 4-methoxybenzyl alcohol. Additionally the results also indicate an efficient separation and recovery of the magnetic catalysts after four successive reuses without any considerable loss in its catalytic activity.

Graphical Abstract

Keywords:

• Sol-gel method
• magnetic materials
• heterogeneous catalyst
• oxidation of aryl alcohols

Acknowledgment

Authors are grateful to the Department of Science & Technology, New Delhi, for the grants under DST-FIST program (No. SR/FST/college-151/2013 (C)) to Jaysingpur College, Jaysingpur.