A robust boehmite-supported cobalt tetraphenylporphyrin catalyst for aerobic oxidation of cyclohexane

Abstract

Using a method of physically adsorbing and chemically coordinating cobalt porphyrin on to boehmite, a new boehmite-supported cobalt tetraphenylporphyrin [Co II TPP/BM] catalyst has been prepared and characterized by UV–Vis, FT-IR, XRD, TEM and TG techniques. The supported catalyst was used for aerobic oxidation of cyclohexane under mild conditions and in the absence of any solvent and additive. The experimental results indicate that, after 10 consecutive uses for the oxidation, a quantity of catalyst containing only 1 mg of cobalt porphyrin, can not only provide, on average, 9.2% cyclohexane conversion, 92.1% selectivity for K/A oil and a catalyst turnover number of 1.14 × 10 5, but also can maintain continuously the original catalytic activity with promotion by beomite (BM). A proposed reason for the good reusability and stability of the supported catalyst for aerobic oxidation of cyclohexane was that the anchored form of the single cobalt porphyrin molecules were highly dispersed and immobilized on the boehmite.