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

Sotiria Papagianni,Anastasia-Maria Moschovi,Ekaterini Polyzou,Iakovos Yakoumis

doi:10.3390/met12010031

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.

Highlights

Heavy-duty vehicles include trucks, buses, lorries, and tractors, which are vital transportation means for a country’s economy
In order to study the leachability of Pt from HDV catalytic devices, a spent diesel oxidation catalysts (DOCs) catalyst and a spent catalyzed filter catalyzed diesel particulate filters (c-diesel particulate filter (DPF))
Monolithic honeycomb and acontact washwith catalyst andthe thecatalyst, toxic emissions areinconverted into flue harmless coat the which contains as shown come Microscopy into contact images reveal a honeycomb-like the DOC catalyst, consistingones

Summary

Introduction

Heavy-duty vehicles include (though they are not limited to) trucks, buses, lorries, and tractors, which are vital transportation means for a country’s economy. Heavy-duty vehicles are mainly powered by diesel engines which provide technical advantages over petrol engines (higher power and less fuel consumption). The transport sector’s growth has led to a rapid increase in the fleet of heavy vehicles, increasing emissions of harmful gases. The main compounds that diesel exhaust gases contain are: carbon dioxide (CO2 ), oxygen (O2 ), nitrogen (N2 ), water vapor (H2 O), sulfur compounds (SOx), hydrocarbons (HC) and particulate matter (PM) of sizes under 10 μm [1]. According to Euro I regulations, the first heavy-duty vehicle emissions standards of the EU, the installation of catalytic devices was not mandatory, whereas in Euro II the installation of DOCs was made obligatory.

Methods

Discussion

Conclusion