A MODIFIED APPROACH FOR ESTIMATING PSEUDO-VAPOR PRESSURES IN THE APPLICATION OF THE DUBININ-ASTAKHOV EQUATION

High pressure adsorption data of methane and hydrogen on four microporous carbons were obtained at supercritical temperatures. The data were analyzed on the basis of the Potential Theory using the Dubinin-Astakhov (D-A) equation. The method for estimating pseudo-vapor pressures proposed by Dubinin resulted in characteristic curves for methane but failed for the hydrogen data. A more general form of Dubinin's method for estimating pseudo-vapor pressures is proposed. This approach introduces a parameter, k, that accounts for interactions in the adsorbate-adsorbent systems under consideration. It was found that the modified approach to the use of the D-A equation leads to reliable prediction of both methane and hydrogen data.