Recovery of platinum from spent catalysts in a fluoride-containing medium

This work presents a study on the dissolution of spent commercial Pt/Al2O3 and PtSn/Al2O3 catalysts in aqueous solutions containing fluoride ions and other species, under mild experimental conditions. Despite fluoride being a strong complexing agent, solubilization of samples in the presence of fluoride only was negligible. Addition of a strong inorganic acid led to support solubilization after 2–4 h (60 °C, 400 rpm). This time was reduced to less than 1 h when hydrogen peroxide was added to the solution, irrespective of the presence of the strong mineral acid. The previous oxidation step of the spent catalyst reduced platinum dioxide to metal in high yield by the coke present in the samples. Processing of other catalyst components was possible with the HF+H2O2 binary mixture. Platinum was recovered as a black powder, with minimal generation of a final residue.