Recovery of Cerium from Automotive Catalytic Converters

Abstract

Platinum group metals (PGM) and cerium as one of the rare-earth elements are considered as critical raw materials, thus their recycling and re-use is of utmost importance. Among the PGMs, platinum (Pt), palladium (Pd), and rhodium (Rh) are the basic and most valuable metals used in catalytic converters. Due to the high price of PGMs, there are already recycling routes in Europe and especially in Germany. For PGM and rare-earth elements, research is focusing on greener, plain recovery techniques, which utilize milder reagents, offer better energy efficiency, and replace the existing recycling routes. In this work, a hydrometallurgical process is proposed to add a hydrometallurgy method to the mostly pyrometallurgical industrial recycling routes, resulting in recovery rates for cerium and PGMs of 63.21% and only 1.03% with sulfuric acid, respectively. With hydrochloric acid, the leaching efficiency for cerium is even lower, and for PGM it is comparable. In the method proposed in the present paper, the main PGMs remain in monoliths and can be recycled in existing recycling routes like pyrometallurgical recycling.