Characterization of porous materials: past, present and future

Although many different experimental methods are now available for characterizing porous solids, some of the more important techniques have undergone very little change over the past 50 years. Thus, it is still customary to make use of over-simplified theoretical models of gas adsorption and mercury intrusion for the determination of surface area and pore size distribution. Another ongoing problem is the complexity of many porous materials of technological importance. Striking progress has been made in modeling certain types of ordered pore structures, but disordered pore networks present a much greater challenge. To facilitate the computation of pore size distribution, there is still a tendency to focus attention on simple assemblages of cylindrical or slit-shaped pores. Future progress will depend on a more critical appraisal of the significance of derived values of surface area, pore size, porosity, fractal dimension, etc. Other future requirements include the development of a range of new reference materials having uniform pore structures.