A New Model for Capillary Condensation−Evaporation Hysteresis Based on a Random Corrugated Pore Structure Concept:  Prediction of Intrinsic Pore Size Distributions. 1. Model Formulation

The present article deals with the development of a new statistical model (corrugated pore structure model: CPSM) simulating capillary condensation−evaporation hysteresis. The formulation of analytical expressions is based on probability principles, an adsorbed layer thickness correlation, Kelvin equation, and a random corrugated pore concept. When the model is fitted over experimental hysteresis loop data, the respective intrinsic pore size distribution (psd) and the corrugated pore parameter, N S (frequency of pore cross-sectional area variation), can be determined. The predictive potential of the CPSM was successfully tested in part 1 (this work) by generating hysteresis loops that reproduced those included in the IUPAC classification as well as those of novel nanoporous MCM-41 materials. CPSM evaluations of intrinsic pore size distributions have been more realistic and accurate than those deduced by applying the conventional methods (e.g., Roberts). The model has been further tested successfully in part 2 (Ind. Eng. Chem. Res. 2000, 39, 3764) by the fitting of experimental hysteresis data of various porous materials, e.g., HDS catalysts, anodic oxide films, lignite, montmorillonite, pillared clays, and MCM-41 mesopore molecular sieves.