Patent ID: 8865618

Claim:
A process for the preparation of a cellular carbon or ceramic monolith comprising a hierarchical porous network comprising interconnected macropores and micropores, said porous network being devoid of mesopores, wherein said process comprises at least the following stages: 1) a stage of preparation of a solid silica template in the form of a cellular monolith composed of a matrix formed of silica or of organically modified silica, said monolith comprising macropores having a mean dimension d A of 1 μm to 100 μm, mesopores having a mean dimension d E of 2 to 50 nm and micropores having a mean dimension d I of 0.7 to 1.5 nm, said pores being interconnected; 2) a stage of impregnation, under vacuum, of the solid silica template with a solution of at least one carbon precursor or of at least one ceramic precursor selected from the group consisting of preceramic polymers resulting in oxycarbonitrides, carbonitrides, nitrides and boronitrides of carbon; 3) a stage of polymerization, crosslinking, or both polymerization and crosslinking of said precursor within the solid silica template; 4) a stage of carbonization of the solid silica template including said polymerized, crosslinked, or polymerized and crosslinked precursor, 5) the production of said carbon or ceramic monolith by removal of the solid silica template by treatment with an acid or a base, said treatment being carried out without distinction before or after said carbonization stage; and in that, during the first stage, the silica template is prepared according to a process consisting of: in preparing an emulsion by introducing an oily phase into an aqueous solution of surfactant, in adding an aqueous solution of at least one silicon oxide precursor, at least one organically modified silicon oxide precursor, or at least one silicon oxide precursor and organically modified silicon oxide precursor to the surfactant solution, before or after the preparation of the emulsion, in leaving the reaction mixture standing until said precursor has condensed, then in drying the mixture in order to obtain the expected solid silica template, and when the silica template is prepared from said aqueous solution of at least one (not organically modified) silicon oxide precursor, then said process furthermore comprises an additional stage consisting in thermally treating the solid silica template at a temperature of at least 650° C.