Separation of Pt from hydrochloric acid leaching solution of spent catalysts by solvent extraction and ion exchange

Leaching of spent catalysts (Pt/Al2O3) with a mixture of HCl and H2O2 results in a mixed chloride solution containing Pt(IV), Fe(III), Al(III), Ni(II), and silicon. Separation of Pt(IV) from the synthetic chloride solution containing Fe(III) and Al(III) has been performed by solvent extraction and ion exchange. Effects of extraction and sorption conditions on the separation of Pt were investigated in the HCl concentration range from 1 to 9 M. In solvent extraction experiments, amines (Alamine304-1, Alamine308, Alamine336, Aliquat336), TBP and TOPO were tested, while AG1-x8 resin was employed in ion exchange experiments. Solvent extraction experiments indicated that it was difficult to separate Pt from Fe and Al by amines and solvating extractants in our tested range. In ion exchange by using AG1-x8 resin, only Pt was loaded from the synthetic solution when HCl concentration was lower than 1 M, while Fe and Al remained in the solution. Continuous experiments with AG1-x8 resin indicated that most of Pt was loaded onto the resin from 0.5 M HCl solution, leaving Fe and Al in the effluent and complete separation of Pt was possible.