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

Abstract

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 °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 °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.

Technology and possibilities of recycling catalysts

“…Conversely, catalysts primarily containing platinum or/and palladium were mostly identified as Diesel Oxidation Catalysts (DOC). Nevertheless, spent catalytic converters with low concentrations of platinum or/and palladium could potentially be labeled as Dual-Function Catalysts, considering additional information such as the vehicle model and manufacturing year [7].…”

“…The PGM content of the two minor samples from each catalyst was gauged, and their average was computed (Tab.3). The homogeneity of the catalyst samples was verified through these measurements [7].…”

“…The quantification of organic deposits was based on the comparison of sample mass before and after the calcination process, conducted at a temperature of 750°C for a duration of 5 hours. The impact of calcination was evident through visual observation, particularly by noting the color alteration in the various samples [7].…”

Leaching Efficiency and Kinetics of Platinum from Spent Proton Exchange Membrane Fuel Cells by H2O2/HCl

“…The pertinent literature indicates that H 2 O 2 serves as a beneficial oxidant in the leaching of platinum with HCl, and it exhibits higher sustainability compared with HNO3 or other inorganic acids. The mechanisms of acidic leaching using H 2 O 2 can be reduced to the following overall reaction Equation (2) [40][41][42]:…”

DES-Based Solution for Regenerating Diesel Particulate Filters of Euro V/VI Diesel Vehicles †

“…These particles are formed as a result of the incomplete combustion of diesel fuel that takes place in the engine. A catalyzed filter (c-DPF) not only traps particulate matter but also uses a patented catalytic technology (Pt as catalyst and Ce/Zr as washcoat) to further oxidize carbon monoxide (CO), hydrocarbons (HC), and diesel particulate matter [1].…”