SUPERHIGH SURFACE-AREA DETERMINATION OF MICROPOROUS SOLIDS

A new method is proposed for the measurement of specific surface area of microporous carbons of superhigh BET surface area. The method (designated the subtracting pore effects (SPE) method) is based on the analysis of two upward swings from linearity, due to the pore effects, in the high resolution alpha(s) plot. The measurement of slope of the linear alpha(s) plot after subtraction of the swings gives a definite surface area, even in a microporous system- The surface area of activated mesophase carbon microbeads with a BET surface area of 3000-4000 m2 g-1 was determined by N2 adsorption using the SPE method. The BET surface area obtained in the usual manner was an overestimate by about 40%. The overestimation was not attributed to enhanced micropore filling but to capillary condensation.