Catalytic Oxidation of Aniline to Azoxybenzene Over CuCr₂O₄ Spinel Nanoparticle Catalyst

Cationic surfactant cetyltrimethylammonium chloride-mediated hydrothermal preparation of CuCr₂O₄ spinel nanoparticles has been reported. This CuCr₂O₄ spinel nanoparticle catalyst has been characterized by XRD, XPS, SEM, TEM, TGA, and ICP-AES. Characterization results showed the formation of CuCr₂O₄ spinel nanoparticles with sizes between 25 and 50 nm. It was found that the catalyst can selectively convert aniline to azoxybenzene with H₂O₂ as oxidant. The effect of different reaction parameters like reaction temperature, H₂O₂ to aniline molar ratio, reaction time, and so forth have been studied in detail. An aniline conversion of 78% with azoxybenzene selectivity of 92% can be achieved over this catalyst at 70 °C. The catalyst did not show any leaching up to five reuses, showing the true heterogeneity of the catalyst. However, significant H₂O₂ decomposition occurs on the catalyst necessitating its usage in five-fold excess