Platinum Recovered from Automotive Heavy-Duty Diesel Engine Exhaust Systems in Hydrometallurgical Operation

The current study is focused on platinum recovery from the secondary sources of end-of-life heavy-duty diesel oxidation catalysts (DOCs) and heavy-duty catalyzed diesel particulate filters (c-DPFs) in order to reduce the supply-demand gap within the European Union. The extraction of platinum was based on a hydrometallurgical single-step low acidity leaching system (HCl-H2O2-NaCl) and a calcination step that takes place before the leaching process. The parameters of calcination and leaching process were thoroughly investigated in order to optimize recovery efficiency. The optimized results proved that a calcination step (at 800 degrees C for 2 h) improves the recovery efficiency by a factor of 40%. In addition, optimal Pt recovery yield was achieved after 3 h of leaching at 70 degrees C, with a solid-to-liquid (S/L) ratio of 70 g/100 mL (70%) and 3 M HCl-1% vol H2O2-4.5 M NaCl as leaching conditions. The optimum Pt recovery yield was 95% and 75% for DOC and c-DPF, respectively. Since the secondary feedstock investigated is highly concentrated in platinum, the pregnant solution can be used as a precursor for developing new Pt-based catalytic systems.

Automated summary

This study focuses on recovering platinum from waste diesel catalysts and filters to address the supply-demand gap in the European Union. By optimizing the calcination and leaching processes, the recovery efficiency was significantly improved. The optimal conditions for leaching were found to be 3 hours at 70 degrees Celsius with a solid-to-liquid ratio of 70 g/100 mL and a leaching solution of 3 M HCl-1% vol H2O2-4.5 M NaCl, resulting in recovery yields of 95% for DOC and 75% for c-DPF.