Characterization of spatial and energetic structures of carbon-silica gels

Carbon/silica (carbosil) samples prepared with mesoporous silica gel (Si-60 ) modified doe to methylene chloride pyrolysis at 550 degrees C were studie d by means of nitrogen adsorption over a broad pressure range of 10(-8) < p /p(o) < 1 analyzed using a constrained regularization procedure with severa l adsorption equations giving detail distributions of the pore size f(R-p), adsorption energy f(E) and fractal dimension f(D-FRDA). The structural cha racteristics of carbosils depend markedly on the amount of carbon deposit a nd the changes in f(R-p) with increasing carbon concentration suggest its g rafting mainly into pores resulting in diminution of the pore volume, speci fic surface area and average mesopore radius. An increase in the concentrat ion of the carbon deposit also causes a slight displacement of the f(E) pea ks towards the high energy, as narrower micropores appear in samples due to carbon grafting. (C) 2000 Elsevier Science B.V. All rights reserved.