| Abstract
| - The paper presents a new Brunauer−Emmett−Teller (BET)-like mathematical model of a non-BETmultilayer adsorption. Small molecule adsorbates and microporous adsorbents containing irregular holelikeand dendritelike pores are considered, in which the formation of stacklike and more compact clusters ofmolecules is possible. A set of nonlinear equations describing the adsorption equilibria with respect toenergetic and geometrical constraints for the cluster size is derived starting from general thermodynamicformulas expressing entropy and energy changes due to the process. The treatment of nonstack clustersneeds modifications in the formulas for the change in configurational entropy. The rigorous and simpleanalytical model, generalizing the BET equation (gBET model), was obtained in the case of unlimitedpores. Analytical formulas were proposed for examination of microporous structures of limited pore size,approximating adequately the above rigorous model in a wide pressure range (LBET and LgBET equations).The models may be used to get more information on the shape and size of pores by fitting empiricaladsorption isotherms in the high-pressure range (up to ca. 0.97 of the relative fugacity). Exemplary resultsof the new model applications to adsorption of CO2, CH4, and N2 on activated carbons are discussed.
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