Abstract
Three theoretical expressions for the adsorption isotherms of hydrogen on LaNi4.75Fe0.25 alloy at 303K and 313K have been established. Our objective in this modeling is to select the adequate model that presents a high correlation with the experimental curves. The establishment of these new expressions is based on statistical physics formalism. This method has allowed the estimation of physicochemical parameters in the theoretical model. The parameters intervening in the adsorption process have been deduced directly from experimental adsorption isotherms by numerical simulation. We will mainly introduce four parameters affecting the adsorption process, namely; the density of hydrogen receptor sites NM, the number of molecules per site and the hydrogen adsorption energy. Then we apply the model to calculate thermodynamics functions which govern the adsorption mechanism such as entropy, free enthalpy and internal energy.
•New models were established to fit hydrogen adsorption isotherm.•The models are able to predict the topography of the gas adsorbed molecules.•The adsorption energy is calculated using the proposed models.•Two phases α and β coexist in the adsorption process.
Adsorption isotherm of hydrogen on LaNi4.75Fe0.25 at 303.15K. The open circles are the experimental data and the line is the simulation data. [Display omitted]