Immobilization of Tetraphenylporphyrin Manganese (III) Chloride in HMS Modified by Zr, Cu, and Zn Oxides and Their Catalytic Activity
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Tetraphenylporphyrin manganese (III) chloride (Mn(TPP)Cl) was grafted on hexagonal mesoporous silica (HMS) modified by Al, Zr, Cu, and Zn oxides. The catalytic performance of these novel materials was investigated by carrying out the oxidation of fatty acid methyl esters at room temperature. XRD, ICP-AES, N2 physisorption, SEM, UV–Vis spectroscopy, FTIR, and thermal analysis were employed to analysis these heterogeneous materials. Enhancement of epoxidation activity for Mn(TPP)Cl/Zn–HMS and Mn(TPP)Cl/Cu–HMS with respect to other samples indicated the participation of promoters in the epoxidation reaction mechanism. A blue shift was observed when compared with the spectra of free Mn(TPP)Cl, which indicated that the nature of promoter influenced the redox properties of the Mn complexes. The hydrophobic nature of heterogeneous materials was determined by thermal analysis, which affected the selectivity of epoxidation. Epoxidation activity was observed over that Mn(TPP)Cl/Zn–HMS (23.2 % for Mn(TPP)Cl/Zn–HMS, 13.8 % for Mn(TPP)Cl/HMS, none for Zn–HMS) demonstrated the promotion by Zn and the catalytic activity remained when the catalysts were recycled three times.
KeywordsManganese (III) porphyrin Epoxidation HMS Fatty acid methyl esters Metal oxides
This work was supported financially by the National “Twelfth Five-Year” Plan for Science & Technology (2012BAD32B03), the National Natural Science Foundation of China (20903048), and the Academy and Research Institutes (BY2010118) in Jiangsu Province of China.