Tetra-substituted cobalt (II) phthalocyanine/multi-walled carbon nanotubes as new efficient catalyst for the selective oxidation of styrene using tert-butyl hydroperoxide

Abstract

A novel tert-butyl hydroperoxide tetrasubstituted cobalt phthalocyanine (CoPc(OC10H14N)4) was synthesized by the classical phthalonitrile method. Subsequently, the cobalt phthalocyanine (CoPc) was immobilized on the multi-walled carbon nanotubes (MWCNTs) by ultrasonic impregnation method to obtain CoPc(OC10H14N)4/MWCNTs composites. The obtained composites were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) and diffuse reflectance spectra (DRS) techniques. Using tert-butyl hydroperoxide (TBHP) as an environmentally friendly oxidant, CoPc(OC10H14N)4/MWCNTs composites can be used as effective catalysts for the epoxidation of styrene. The effects of various variables, such as the mass ratio of CoPc(OC10H14N)4/MWCNTs, reaction time, temperature, molar ratio of substrate/oxidant and the amount of catalyst on the catalytic capability were evaluated. The conversion of styrene reached 97.15%, and the epoxidation product achieved the selectivity of 84.44% under the optimal reaction conditions.