Effect of Zinc Substitution on the Structure and Catalytic Activity of Copper Chromite Spinels for Cyclohexane Oxidation

Zinc-substituted copper chromite spinels with the general composition Cu₁₋xZnₓCr₂O₄ (x = 0, 0.25, 0.50, 0.75, and 1.00) were synthesized by the homogeneous co-precipitation method. The synthesized materials were systematically characterized using powder X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, energy-dispersive X-ray (EDX) spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy. The XRD patterns confirmed the formation of the spinel phase, while EDX analysis verified the elemental composition and stoichiometry of the prepared materials. The catalytic performance of the synthesized spinels was evaluated for the liquid-phase oxidation of cyclohexane using 70% tert-butyl hydroperoxide (TBHP) as the oxidizing agent. The results demonstrated that the zinc-substituted copper chromite spinels exhibit significant catalytic activity towards cyclohexane oxidation. Furthermore, reusability studies indicated that the catalysts retain their catalytic performance and structural stability under the employed reaction conditions, demonstrating their potential as reusable heterogeneous catalysts for liquid-phase oxidation reactions.