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

Abstract

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.