Selective oxidation of cyclohexane to KA oil over Co and Fe nanoparticles immobilized on layered double hydroxide nanocatalytic system†

In this study, we prepared Co and Fe nanoparticles supported on a layered double hydroxide abbreviated as CoNPs@LDH and FeNPs@LDH. The nanostructured catalysts were characterized using inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, infrared spectroscopy (FTIR), X-ray photoemission spectroscopy (XPS), BET surface area analysis and thermogravimetric analysis (TGA) and tested for the oxidation of cyclohexane to KA oil using tert-butylhydroperoxide (TBHP) under solvent-free conditions. CoNPs@LDH appeared to have higher catalytic efficiency than FeNPs@LDH nanocatalysts. Structural analysis revealed that the transition metal nanoparticles are well anchored on the layered double hydroxide, resulting in a fine dispersion of the Co nanoparticles. The CoNPs@LDH nanocatalyst demonstrated a 45.7% conversion of cyclohexane with 95.8% selectivity of KA oil under optimal reaction conditions. Furthermore, the recycling experiment revealed that CoNPs@LDH was a heterogeneous catalyst that could be recycled at least five times without significant loss of catalytic activity. A possible mechanism following the free radical pathway has been proposed.