Characterization of spatial and energetic structures of carbon–silica gels

Carbon/silica (carbosil) samples prepared with mesoporous silica gel (Si-60) modified due to methylene chloride pyrolysis at 550°C were studied by means of nitrogen adsorption over a broad pressure range of 10−8<p/p0<1 analyzed using a constrained regularization procedure with several adsorption equations giving detail distributions of the pore size f(Rp), adsorption energy f(E) and fractal dimension f(DFRDA). The structural characteristics of carbosils depend markedly on the amount of carbon deposit and the changes in f(Rp) with increasing carbon concentration suggest its grafting mainly into pores resulting in diminution of the pore volume, specific surface area and average mesopore radius. An increase in the concentration of the carbon deposit also causes a slight displacement of the f(E) peaks towards the high energy, as narrower micropores appear in samples due to carbon grafting.