Silica and carbon monoliths with hierarchical porosity prepared by Spark Plasma Sintering (SPS)

Silica SBA-15 and carbon CMK-3 display a high specific surface area and an important mesoporous volume. The mesopores are organized in a hexagonal symmetry (space group p6 mm). It can be interesting to preserve these characteristics during the processing of these powders for several applications. The Spark Plasma Sintering of these powders has been realized with or without uniaxial pressing of 25 MPA and at temperatures ranging from 600 to 800 degrees C and from 1100 to 1300 degrees C, for silica and carbon, respectively. The nitrogen adsorption/desorption isotherms show that the high surface area of the powders is preserved in the derived monoliths (300 to 500 m(2)/g) whereas the mesoporous volume of the latter is around 0.7 cm(3)/g. The coexistence of interconnected mesoporosity and macroporosity with similar volumes has been observed by SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy. Moreover, the organization of the mesoporosity is partially maintained as it has been evidenced by X-ray diffraction analysis and TEM (Transmission Electron Microscopy).