Synchronous Synthesis And Immobilization Of Metal Phthalocyanine For Aerobic Oxidation Of Styrene

In this study, the precursor 4-(4-carboxy-phenoxy) phthalonitrile (CPPN) was first bonded onto the silica gel surface modified with poly(glycidyl methacrylate) (PGMA) (PGMA/ SiO2) to prepare CPPN-PGMA/SiO2, and metal phthalocyanine (MPc; M=Co, Fe, Cu, Mn) was supported on the PGMA/SiO2 surface to prepare MPc-PGMA/SiO2 by synchronous synthesis and immobilization with phthalonitrile and metal salt in the solution. The chemical composition and surface morphology were characterized by the Fourier transform infrared (FTIR) spectroscopy, UV-Vis spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetry analysis (TGA). The catalytic performance of MPc-PGMA/SiO2 in epoxidation of styrene was also investigated with molecular oxygen acting as the oxidant. The results show that MPc-PGMA/SiO2 can efficiently and selectively catalyze molecular oxygen for oxidation of styrene to styrene oxide under mild conditions. However, the catalytic activity differs substantially depending on the central metal, and a highest catalytic activity is achieved by CoPc-PGMA/SiO2. The CoPc-PGMA/SiO2 amount and temperature can also affect the catalytic oxidation of styrene, and at normal atmospheric pressure, a maximum conversion rate of styrene (99%) and selectivity of styrene oxide (53%) are obtained using 0.1 g of CoPc-PGMA/SiO2 (22.61 mu mol of CoPc) at 100 degrees C for 6 h. CoPc-PGMA/SiO2 also has excellent reusability, and the conversion rate of styrene is still over 90% after 5 cycles.