Efficient recovery of critical metals from spent reforming catalysts and regeneration into highly active Pt-based catalysts for hydrogen evolution reaction

The sustainable recovery and value-added utilisation of active metals, Pt and Re, from spent reforming catalysts represents a significant challenge in the context of industrial catalyst recycling.This study proposes an enhanced method for the selective separation and high-value utilisation of Pt and Re through the implementation of sodium roasting and weak base leaching processes.The integration of these two processes resulted in phase separation, whereby Re and Al were preferentially dissolved, while Pt was concentrated in the slag phase. Subsequent adsorption on an ion exchange resin exhibited excellent selectivity for Re/Al separation, with adsorption and desorption efficiencies of 99.67 % and 99.82 % for Re, respectively.The residual Pt was effectively recovered by oxidative acid leaching, with a combined recovery of 98.89 %.In view of the presence of trace Fe in the leach solution, the potential synergistic effect of Pt utilisation was further explored in this study. The prepared Pt/ Fe@C-M intermetallic catalysts exhibited excellent electrocatalytic performance for HER, with an overpotential of 28 mV at 10 mA center dot cm-2, which exceeded that of commercially available Pt/C catalysts.The improved performance is attributed to the beneficial electronic effect of iron in the catalyst structure. A cost-benefit analysis of the integrated recovery and value-added process was conducted, demonstrating significant commercial viability, with a net profit of $549.89 per kilogram of spent catalyst.