Immobilization of manganese tetraphenylporphyrin on boehmite and its catalysis for aerobic oxidation of cyclohexane

The search for a reusable material as an efficient and economic catalyst for hydrocarbon oxidation is an important field of research. In this study, we investigated the highly effective combination of support and metalloporphyrin provided by manganese tetraphenylporphyrin adsorbed onto a precursor of freshly precipitated aluminium hydroxide, followed by conversion to a manganese porphyrin/boehmite compound. This was characterized using FT-IR, UV–vis spectroscopic techniques, N2 BET analysis, X-ray powder diffraction, transmission electron micrograph technique and thermal analysis. Aerobic oxidation of cyclohexane has been investigated using the compound as a catalyst under mild conditions and in the absence of any solvent and reductant. The results indicate that it has higher catalytic activity than manganese tetraphenylporphyrin and the corresponding chitosan-supported catalyst. In particular, the catalyst exhibits good atom economy for cyclohexane oxidation, high catalyst turnover number, and good ketone and alcohol selectivity. In particular, it has excellent reusability, with no change in original catalytic activity; a quantity of catalyst containing only 1 mg of Mn TPP can be reused 8 times under the promotion of beomite (BM). In addition, we examined the reaction conditions for the use of such nanoparticle-supported manganese tetraphenylporphyrin as a mild and environmental friendly oxidation catalyst.

Graphical abstractA new supported metalloporphyrin catalyst, manganese tetraphenylporphyrin/boehmite containing only 1 mg of Mn TPP, was used for the aerobic oxidation of cyclohexane into ketone and alcohol. This material could be reused 8 times with no change of original catalytic activity. On average, the material exhibited 12% cyclohexane conversion, 86% selectivity for main products and a catalyst turnover number of 1.49 × 105.Figure optionsDownload full-size imageDownload as PowerPoint slide