Processing of spent platinum-based catalysts via fusion with potassium hydrogenosulfate

This work describes a route for processing spent platinum-based commercial catalysts (Pt and PtSnIn/Al2O3) via fusion with potassium hydrogenosulfate (KHSO4). Samples were previously ground. The optimized experimental parameters were: temperature, 450 °C; time, 3 h; sample/flux mass ratio, 1/10. The fused mass was dissolved in water and the elements present were isolated by a multi-step separation procedure. Platinum was recovered as the only water-insoluble residue. About 45 wt% of aluminium was recovered as KAl(SO4)2·12H2O (alum), whereas the remaining element was recovered as Al(OH)3. Tin and indium were recovered together as sulfides at pH 1. About 72 wt% of potassium was recovered as K2SO4 when the final effluent was treated with sulfuric acid (pH 1) and slowly evaporated. Generation of final wastes was greatly reduced. More than 98 wt% of the elements present in the catalysts examined was recovered.