Effective catalysis of simple metalloporphyrins for cyclohexane oxidation with air in the absence of additives and solvents

Abstract

Simple iron, manganese and cobalt tetraphenylporphyrins were synthesized and used to catalyze cyclohexane oxidation with air in the absence of additives and solvents. These simple metalloporphyrins were first found to be the very effective catalysts for cyclohexane oxidation with air when the reaction temperature was higher than 100 °C and pressure was greater than 0.4 MPa. The research results showed that the metalloporphyrins type, temperature, pressure and catalyst concentration influenced the yields and conversion of cyclohexane oxidation with air. The catalytic activity of cobalt porphyrins was superior to that of iron and manganese porphyrins. For cyclohexane oxidation catalyzed by simple cobalt tetrapherylporphyrin, the conversion of cyclohexane was up to 16.2%, general yields of cyclohexanol and cyclohexanone was 82%, and the mole turnover numbers of the catalyst reached 400,000 under the optimum conditions of 0.6 MPa and 140 °C and 4 ppm cobalt porphyrin.