The microporous phase of carbonaceous substances and its fractal dimension

The microporous phase of carbonaceous materials is characterized by means of fractal dimension D, determined on the principle of the coverage of microporous body of ideal shape with a monolayer of molecules of various sizes. A part of molecules remains lying on the external surface of the solid phase characterizing it with the dimension D=2 and another part enters into the micropores (with dimension D=3) respecting their size distribution. The combination of both dimensions gives the resulting value of fractal dimension within interval 2<D<3. The fractal dimension of bituminous coal, cokes and carbonization products prepared at different temperatures of heat treatment were determined. The characteristic parameters of the microporous structure necessary for D evaluation were obtained from carbon dioxide isotherm, for active carbon they were calculated from the isotherms of CO2 and some hydrocarbons.