Synthesis of thermally stable silica-pillared layered manganese oxide by an intercalation/solvothermal reaction

Silica-pillared layered manganese oxide with high surface area and high thermal stability was first synthesized from birnessite(H)-type manganese oxide by intercalation of octylamine followed by tetraethyl orthosilicate (TEOS) molecules and then by solvothermal treatment in TEOS liquid. Layered phases of manganese oxide with basal spacings of 2.01 and 2.43 nm, respectively, were obtained for each intercalation reaction. The Si/Mn molar ratio increased from 0.63 to 0.84 by the solvothermal treatment, but the basal spacing (2.44 nm) of the layer barely increased. The increase of silica content stabilized the pillared structure against thermal treatment. Porous layered manganese oxides were obtained by heating the silica-pillared material at appropriate temperatures. The manganese oxide sample obtained at 400 degreesC had a BET surface area of 260 m(2)/g with a gallery height of about 1.6 nm between layers.