Selective oxidation of styrene over nanosized spinel-type Mg xFe 3− xO 4 complex oxide catalysts

Abstract

Nanosized spinel-type Mg x Fe 3− x O 4 complex oxide catalysts were prepared by coprecipitation and citrate gel methods and were characterized. The crystallization temperature of spinel particles prepared by citrate gel method is about 300 °C lower than that of those prepared by coprecipitation method. Mg x Fe 3− x O 4 catalysts prepared by citrate gel method have higher dispersity and smaller particle size, leading to higher activity for styrene oxidation with H 2O 2 as oxidant. The nonstoichiometric Mg x Fe 3− x O 4 catalysts ( x<1) are more active for styrene oxidation than the pure spinel MgFe 2O 4. The major reaction (∼65–70 mol%) is oxidative CC cleavage into benzaldehyde, and the minor reaction (10 mol%) is epoxidation and its further isomerization into phenylacetaldehyde. The effects of solvent, styrene:H 2O 2 molar ratio, reaction temperature and time on the conversion and product distribution were also studied.