Theoretical Prediction of Rhenium Separation from Ammonium Perrhenate by Phonon–Photon Resonance Absorption

Rhenium (Re) is an extremely rare and precious element that is mainly used in the construction of aerospace components and satellite stations. However, an efficient and simple method for preparing Re has yet to be devised. To this end, we investigated the vibrational spectrum of ammonium perrhenate (NH₄ReO₄) using the CASTEP code based on first-principles density functional theory. We assigned the infrared (IR) absorption and Raman scattering spectra for NH₄ReO₄ using a dynamic process analysis of optical branch normal modes. We examined the IR-active peaks of Re-related vibrational modes in detail and found that the typical IR peak at approximately 914 cm^–1 is due to the Re–O bond stretching. Thus, we posit that strong terahertz laser irradiation of NH₄ReO₄ at 914 cm^–1 will lead to sufficient resonance absorption to cleave its Re–O bonds. This method could potentially be used to efficiently separate Re from its oxides.