Radial distribution of porosity in spherical activated carbon particles

The radial distribution of porosity in spherical activated carbon particles and its relationship to both activation temperature and conversion of the reaction C-CO2 are discussed. Char spheres, obtained by pelletizing Quercus agrifolia powdered char, were activated using CO2 as activating agent at 820 and 860 T. For both temperatures. the gasification reaction was run until the desired conversion (30, 50 and 70%) as reached. The activation process was performed using TGA apparatus. The porosity of the samples was measured by physical adsorption of nitrogen at - 196 degreesC, BET and Dubinin-Raduskhevich equations were used to analyse the results. From each activated carbon sphere several samples ere prepared. corresponding to different layers of the sphere: an outer layer. a middle layer and the core of the particle. From these results, the radial porosity evolution as a function of activation temperature and reaction conversion was, obtained and a mathematical expression that correlates pore volume evolution and reaction conversion is proposed. (C) 2002 Elsevier Science Ltd. All rights reserved.