Quantification of Kr/Xe co-adsorption using in situ powder diffraction and X-ray adsorption (fluorescence)

This proposal is dedicated to the determination of simultaneous kinetics of Kr and Xe adsorption in the porous #-Mg(BH4)2. Such system was selected due to its narrow quasi-1D pore structure of # 7 Å pore size, matching the criteria for effective capture and separation of these gas molecules adopting one and two kinetic diameters of Kr (3.6–7.2 Å) and Xe (3.95–7.9 Å). We observed several intermediate phases for Kr and Xe in these pores from our previous synchrotron experiment and parametrized the kinetics of Kr and Xe adsorption from in situ X-ray diffraction. The latter suggests two various diffusion models depending on the guest size: single kinetic barrier for Xe and two barriers for Kr uptake. Here, we propose to investigate the kinetics of uptake from various Kr/Xe mixtures and compare them with the single-component behaviour. We will use the Kr K-edge X-ray adsorption (fluorescence) signal, giving a significant background response to Kr content.