Validation of the atomistic modeling of water sorption onto silicoaluminophosphate for sorption storage applications

This paper presents the experimental characterization and atomistic modelling of water sorption onto a commercial silicoaluminophosphate (SAPO-34) for sorption thermal storage applications. The measured adsorption isotherms were classified as type V, with a "S" shaped evolution which allows to obtain good sorption storage capacity already at low regeneration temperature (i.e. 80°C). The atomistic model approach demonstrated to be able to satisfactorily represents the isotherm of adsorption, with slight discrepancies at p/p0<0.1, which might be due to the non-ideality of the tested SAPO-34 structure. Similarly, also the heat of adsorption was simulated, showing good agreement with the experimental data for hydration levels higher than 50%. Further investigation will be performed, to better characterize the crystalline structure of the adsorbent material as well as to refine the numerical model, in order to be able to closely replicate both isotherms of adsorption and heat of adsorption.