Thermal Analysis of Benzotriazolium Perrhenate and Its Implication to Rhenium Metal

The thermal analysis behavior of C₆H₆N₃[ReO₄] was studied by simultaneous thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) up to 700 °C under argon. Such analysis afforded rhenium metal, which was characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. XRD peak broadening due to crystallite size and lattice strain was analyzed by both Williamson–Hall (W–H) and Debye–Scherrer (D–S) methods. Efforts to isolate Re metal from the thermal treatment of benzotriazole (BTA = C₆H₅N₃) with NH₄ReO₄ and Re₂O₇ under various atmospheres and temperatures are also reported. The results provide a significant insight into the chemistry of group VII transition metals, investigate the potential use of benzotriazole as a reducing agent for metal productions, and demonstrate a successful convenient method for rhenium metal production, which could be applied to other refractory metals.