A DFT study of RuO4 interactions with porous materials: metal–organic frameworks (MOFs) and zeolites

Abstract

Radioactive gaseous ruthenium tetroxide (RuO₄) can be released into the environment in the case of a severe nuclear accident. Using periodic dispersion corrected density functional theory calculations, we have investigated for the first time the adsorption behavior of RuO₄ into prototypical porous materials, Metal–Organic Frameworks (MOFs) and zeolites, with the aim of mitigating ruthenium releases to the outside. For the MOFs, we have screened a set of six structures (MIL-53(Al), MIL-120(Al), HKUST-1(Cu), UiO-66(Zr), UiO-67(Zr) and UiO-68(Zr)), while for the zeolites two structures have been selected: mordenite (MOR) with Si/Al ratios of 11 and 5, and faujasite (FAU) with a Si/Al ratio of 2.4. The DFT calculations show that the nature of the porous materials does not have a significant effect on the adsorption energy of RuO₄ compounds and that the main interaction is due to the formation of hydrogen bonds. For the tested materials, computational results show that the interaction energies of RuO₄ reach their maximum with the hydrated form of HKUST-1(Cu) (−114 kJ mol⁻¹) due to the presence of strong hydrogen bonds between the water molecules and the oxygen atoms of RuO₄.