Preparation of zinc (II) porphyrin with a mesoporous structure and its photoctalytic properties for the oxidation of aromatics

Abstract

Mesoporous molecular sieve MCM-41 was used as support for the immobilization of bulky zinc(II)-5, 10, 15, 20-tetraphenylporphyrin (ZnTPP). Zinc porphyrin was prepared via the treatment of ZnCl2 with 5, 10, 15, 20-tetraphenyl- 21H, 23H-porphyrin in dimethylformamide (DMF). The product was crystallized and characterized by Ultraviolet Visible spectroscopy (UV-Vis) and Fourier Transform Infrared spectroscopy (FTIR spectroscopy). ZnTPP encapsulated inside the mesoporouse of ordered structure of MCM-41 with three different concentrations were prepared by treatment of zinc porphyrin with MCM-41 in DMF in room temperature. The materials obtained were characterized by X-ray Diffraction (XRD), and Ultraviolet Visible Diffuse Reflectance (UV-Vis DR) spectroscopy. The powder XRD data confirmed that the ordered structure of mesoporouse MCM-41 remained intact after encapsulation process. Characterization of ZnTPP composite with MCM-41 using UV-Vis DR confirmed that the structure of ZnTPP in the support is similar with bare ZnTPP. Encapsulated ZnTPP as catalyst in a photoexcited system was found to be active and selective in the D-limonene biotransformation under mild condition with hydrogen peroxide as the oxidant. The influence of different concentrations of catalyst was studied for photocatalytic oxidation of D-limonene to carvone. The products were identified by using Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS).