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Topological organization and textural changes of carbon macro-networks submitted to activation with N<inf>2</inf> and CO<inf>2</inf>

Abstract:

Polygonal macro-networks of carbon in the form of films were synthesized by the controlled pyrolysis of saccharose with or without potassium in the form of KOH. The topological organization of these random two-dimensional networks differ significantly from other two-dimensional cellular structures. The pentagon was the most abundant polygon in the film networks, which had ring areas in the range of 4 to 12 mm2. In addition to two-dimensional films, we also obtained irregular three-dimensional sponge-like balls featuring a random network structure similar to that obtained in the films. These sponges developed in the form of coiled tubes. We attribute the formation of these carbon macro-coils to the presence of potassium particles inside the original carbonaceous matrix. A study of textural changes of the macro-networks of carbon by activation under flow of N2 and CO2 has shown that activated carbon with surface areas as high as 980 m2 · g -1 can be obtained from non-activated macro-networks. From our study of textural changes, we propose a detailed mechanism that explains the role of KOH as a catalysts for the activation of the macro-networks of carbon. © 2004 Kluwer Academic Publishers.