Adsorption is widely applied in several practical processes. Thus, the development of mathematical tools for modeling adsorption systems is remarkably relevant. In the past few years, we have extended commonly used equations of state to fluids confined in cylindrical pores and the obtained models were successful in describing the adsorption of pure fluids and mixtures. In this work, we follow our previous approach to extend the Peng-Robinson equation of state to fluids confined in slit pores, based on molecular simulations of structural properties of the confined fluid. Furthermore, we investigate the potential of this modeling to provide pore size distributions of cylindrical- and slit-pore solids from pure fluid adsorption data. Predictive calculations of mixture adsorption were carried out with the obtained pore size distributions and the modeling showed a good performance, comparable to predictions of density functional theory. (C) 2019 Elsevier B.V. All rights reserved.