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

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 . 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 . Application of Fe₂O₃ 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.