Abstract
By means of the grand canonical ensemble and using statistical physics, experimental adsorption isotherms of hydrogen on three adsorbents (zeolite A, X and Y) at T = 77 K have been best fitted with a developed monolayer model with one type of sites. Exploiting some simplifying hypotheses, the model analytical expression of this model was established involving three physicochemical parameters with which we can describe the adsorption process at a microscopic level. These characteristic parameters are: the number of hydrogen molecules per site n, the receptor site density Nm and the energetic parameter P1/2 which are all deduced from the experimental data by numerical simulation. The evolution of these parameters was investigated of different types of zeolite and different type of exchanged cations. Our fitting results revealed that the hydrogen adsorption surface for each zeolite is homogeneous with physical bond energies. Finally, the thermo-dynamical potential functions which govern the adsorption process such as internal energy Eint, free enthalpy of Gibbs Ga and entropy Sa are derived by statistical physics derivation from the adopted model.
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•Application of statistical physics models to desribe the adsorption of hydrogen in zeolites A, X and Y.•Steric and energetic interpretations of hydrogen adsorption process are given.•a thermodynamic study is applied to calculate internal energy, free enthalpy and entropy.