Preparation of MgO with High Surface Area, and Modification of Its Pore Characteristics

Abstract

Thermal decomposition of hydrated surface layer of Mg(OH)2 at 500 °C in vacuum turned non-porous MgO into porous one with high surface area of around 270 m2/g. Most of its surface area, 74%, was from micropores, and rest of it was from mesopores in wedge-shaped slits, exhibiting bimodal size distribution centered around 30 and 90 Å. Rehydration followed by subsequent dehydration at 300 °C in dynamic vacuum further raised the surface area to 340 m2/g. Fraction of microporous surface area was increased to 93%, and the shape of the mesopores was modified into parallel slits with a specific dimension of 32, Å. Application of Fe 2O3 over MgO via iron complex formation did not alter the pore characteristics of MgO core, except slightly increased pore dimension. Over the course of the modification, Fe2O3 stayed on the surface possibly via spill-over reaction.