Experimental and numerical study of hydrogen absorption in the MmNi5_ xMx compound

In this paper, the hydrogen storage properties of the MmNi4.6Al0.4 and MmNi4.6Fe0.4 compounds are compared experimentally and theoretically. The experimental curves of the activation process, experimental isotherms of absorption and the Van't Hoff's plot were first investigated. Following that, a theoretical model is contrasted with the experimental data. The mathematical equations of this model contain parameters, such as the number of hydrogen atoms per site (n1, n2), the densities of the receiving sites (N1m, N2m), and the energy parameters (P1, P2). All these parameters are obtained by numerically adjusting the experimental data. Depending on the applied temperature, the relevant parameters of the suggested model were identified and described. Entropy, internal energy, and other thermodynamic variables that govern the absorption reaction were all calculated and displayed as a function of pressure and temperature.