(33g) A New Approach in the Modelling and Characterization of Porous Carbon With Argon and Water

Characterization of porous carbon to determine the pore size distribution and its derivatives (surface area, pore volume and average pore size) is traditionally carried out with the implicit assumption of a pore model that has slit-like pores of uniform length having both ends open to the surrounding external gas phase.  This ideal model does not adequately describe the inherently complex structure of porous carbons where the presence of functional groups should be accounted for.  A better model should be simple enough in  its application, not only in the characterization, but also for the design of separation and purification processes.  Specifically, the following factors should be accounted for: (1) energetic variation along the pore axis due to constrictions etc., (2) connectivity between adjacent pores and (3) the presence of functional groups.  In this presentation, we report detailed computer simulation results for a new model for porous carbon, which includes pore size variation, constrictions, and functional groups, with argon as a representative of non-polar adsorbate and water as an example of strongly associating fluids.  The new model is able to produce all types of hysteresis loops reported in the IUPAC classification, especially the Type H3 and H4, commonly attributed to carbon materials.  Analysis of the experimental data with the new model gives a pore size distributions, different from those obtained by conventional analysis, and the concentration of the functional groups.