Platinum Group Metals: Green Recovery from Spent Auto-Catalysts and Reuse in New Catalysts-A Review

This manuscript reviews the current trends in the recovery of Platinum Group Metals (PGMs) from end-of-life autocatalysts and the aims of the recently funded Marie Sklodowska-Curie Project "Chemistry of Platinum Group Metals-CHemPGM" towards the greening of PGMs recovery processes and the reusing of recovered PGMs for preparation of new catalysts. Together with the analysis of the state of the art recovery of PGMs from spent autocatalysts through pyrometallurgical and hydrometallurgical routes and the recent trends in reducing their environmental impact, also emerging sustainable and green technologies are analyzed. Particular focus is given on the mechanochemical processing as a promising sustainable route not only for the pretreatment of waste materials but also for direct PGMs leaching. The present review identifies also the trends in catalysts for carbon neutrality and the few recent efforts in developing PGM-based catalysts starting directly from the liquor of the leach solutions of spent catalysts envisaging therefore a possible key to close PGMs loop in a more efficient and sustainable way.