Role of manganese oxide octahedral molecular sieves in styrene epoxidation

Abstract

Manganese oxide octahedral molecular sieves having 2×2 tunnel structure OMS-2) and synthesized by different methods were used for studying styrene oxidation with tert-butyl hydroperoxide (TBHP) as the oxidant. The catalytic activity of the as-synthesized OMS-2 materials was investigated. The physical and chemical properties of the OMS-2 materials are related to their activity in styrene oxidation. This particular study emphasizes the acid-base properties and the porous nature of these materials, and their role in styrene oxidation. Results of styrene oxidation reveal that acidity coupled with high porosity play a crucial role in these catalytic reactions. A desired acidity coupled with pore volume found in OMS-2 synthesized by reflux methods (OMS-2R) and high-temperature methods (OMS-2HT) produces materials with higher styrene conversion and styrene oxide selectivity when compared with OMS-2 synthesized by solvent free (OMS-2s), microwave (OMS-2MW), or hydrothermal methods (OMS-2HY). Transition metal doped OMS-2 catalysts show better selectivity of styrene oxide when compared to their undoped catalysts. © 2006 American Chemical Society.