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

Thermal decomposition of hydrated surface layer of $Mg(OH)_2$ at $500^{\circ}C$ in vacuum turned non-porous MgO into porous one with high surface area of around $270 m^2$ /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 ${\AA}$ . Rehydration followed by subsequent dehydration at $300 ^{\circ}C$ in dynamic vacuum further raised the surface area to 340 $m^2$ /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 ${\AA}$ . Application of $Fe_2O_3$ 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, $Fe_2O_3$ stayed on the surface possibly via spill-over reaction.