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 metallotetraphenylporphyrins (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 highest 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 O2 activation of the different bivalent metal ions, which affects the activity of the corresponding chitosan-supported MTPPs and chitosan assistance of the MTPP catalysis.

Graphical abstractCyclohexane oxidation was catalyzed by chitosan-supported chloro (tetraphenylporphyrinato) iron or manganese, and (tetraphenylporphyrinato) cobalt complexes. It was found that the supported catalysts had different catalytic activity and selectivity for ketone and alcohol, and that the catalytic activity of the supported metaloporphyrins depended on the different character of metalloporphyrins and the properties of chitosan microenvironment. Figure optionsDownload full-size imageDownload as PowerPoint slide