Method for the calculation of effective pore size distribution in molecular sieve carbon.

TLDR

A method for calculating effective pore size distribution from adsorption isotherms in molecular‑sieve carbon is presented. The method uses an average potential function to calculate pore size distribution without relying on the Kelvin equation, is applicable over a wide pore‑size range, is illustrated with two N₂ isotherm examples at 77.4 K, and can be extended to other pore shapes and adsorbent–adsorbate pairs. The method is theoretically and practically more accurate than prior approaches, determines an average potential function in slit‑like pores, but yields poor values for larger pores, which can be improved by combining it with the Dollimore‑Heal method at 1.34 nm.

Abstract

A method for the calculation of effective pore size distribution from adsorption isotherms in molecular-sieve carbon is described. This method is more exact theoretically as well as practically than previously described methods. An average potential function has been determined inside the slit-like pores. With the help of this function the doubtful use of the Kelvin equation can be avoided at the scale of molecular dimensions. The method gives poor values for the larger pores but can be combined with the well-known Dollimore-Heal method at a pore size of 1.34 nm. Calculation is possible over a wide range of pore sizes. The calculation is shown through two examples from N2 isotherms at 77.4K. The model can be extended to other pore shapes as well as to other adsorbent-adsorbate pairs.