Epoxidation of Styrene with Hydrogen Peroxide over MgO Catalyst

A solid MgO catalyst was prepared by direct thermal decomposition of the Mg(NO3)(2)center dot 6H(2)O precursor. The epoxidation of styrene was studied over the MgO using H2O2 as an oxidant in the presence of acetonitrile as solvent. The catalyst samples were characterized by X-ray diffraction, N-2 adsorption-desorption, thermogravimetry, and CO2 temperature-programmed desorption. The results indicated that the strength of basic sites on the MgO catalyst is the key factor for the excellent performance of the catalyst. Enhancement of the strength of basic sites can increase the styrene conversion. In contrast, the number of basic sites, surface area, and pore volume of MgO have a relatively minor effect on catalytic activity. The MgO sample prepared by calcining Mg(NO3)(2)center dot 6H(2)O at 750 degrees C showed the most strength of basic sites and the highest catalytic activity among the MgO samples calcined at 450-850 degrees C. Under the optimized reaction conditions, H2O2/styrene molar ratio = 6, acetonitrile as solvent, 60 degrees C, and 10 h, the conversion of styrene and the selectivity to epoxyethylbenzene were 97.0% and 88.4%, respectively.