Catalysis of cyclohexane oxidation with air using various chitosan-supported metallotetraphenylporphyrin complexes

Three types of chitosan-supported metallotetraphenylporphyrins were prepared at room temperature by loading iron, cobalt and manganese tetraphenylporphyrins (TPP) onto chitosan. These were employed as catalysts for the aerobic oxidation of cyclohexane in the absence of additives and solvents. Three chitosan-supported and three simple metal lotetraphenylporphyrin s (MTPPs) showed different catalytic activity for the oxidation of cyclohexane. Under optimum reaction conditions of 418 K and 0.8 MPa, both the cobalt TPP and the corresponding chitosan-supported complex showed the hi-hest catalytic activity, but lower ketone and alcohol selectivity. The reverse situation was observed for the iron TPP and the corresponding chitosan-supported complex. For cyclohexane oxidation, there was a difference in catalytic activity and ketone and alcohol selectivity between the simple MTTPs or the corresponding chitosan-supported complexes. These differences in catalysis probably result from two factors: the potential for O-2 activation of the different bivalent metal ions, which affects the activity of the corresponding chitosan-supported MTPPs and chitosan assistance of the MTPP catalysis. (c) 2006 Elsevier B.V. All rights reserved.