ABSTRACT
In the chemical industry, designing high-performance catalysts for the oxidation of cyclohexane into value-added products such as cyclohexanol and cyclohexanone (the combination is known as KA oil) is critical. The catalytic activity of copper nanoparticles supported on layered double hydroxide (LDH) for the liquid phase oxidation of cyclohexane was examined in this study. In this work, we have developed Cu nanoparticles supported on layered double hydroxide nanocatalysts, abbreviated as CuNPs@LDH, by the chemical reduction approach. Various physical methods were used to characterize the resulting material, including ICP-AES, XRD, FTIR, SEM, EDX, HRTEM, and BET surface area. The catalytic activity of copper nanoparticles supported on LDH was examined for the liquid phase oxidation of cyclohexane with tert-butyl hydroperoxide. CuNPs@LDH nanocatalysts with an excellent 52.3% conversion of cyclohexane with 97.2% selectivity of KA oil was obtained after 6 h at 353 K. The hot filtration test further indicated that CuNPs@LDH was a heterogeneous catalyst that could be recycled at least six times without suffering a substantial reduction in its catalytic activity.
ABSTRACT
A new heterogeneous catalyst was prepared by intercalation of NNOO donor Cu(ii) Schiff base complex derived from 2-hydroxy-1-naphthaldehyde and 4-amino benzoic acid into Zn-Al layered double hydroxide {LDH-[NAPABA-Cu(ii)]}. Synthesized catalyst was characterized by Inductively coupled plasma atomic emission spectroscopy, energy dispersive X-ray analysis, scanning electron microscopy, X-ray diffraction, Transmission electron microscopy, BET surface area, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, electron paramagnetic resonance spectroscopy and diffuse reflectance UV-visible spectroscopy. The catalytic performance of LDH-[NAPABA-Cu(ii)] was studied for the liquid phase solvent-free oxidation of ethylbenzene at 393 K, using tert-butylhydroperoxide as an oxidant. In oxidation reaction ethylbenzene was oxidized to acetophenone, benzaldehyde and benzoic acid. The major product was acetophenone. A maximum, 80.54% conversion of ethylbenzene was observed after 7 hours. The catalyst was recycled seven times without significant loss of catalytic activity.
