Recent Advances in Platinum and Palladium Solvent Extraction from Real Leaching Solutions of Spent Catalysts

The strategic importance of platinum and palladium, two platinum-group metals (PGMs), is particularly supported by their technological applications, one of the most relevant being the role they perform as catalysts for several sorts of chemical reactions. The cumulative demand for these two PGMs to be used as catalysts more than justifies increasing research efforts to develop sustainable recycling processes to maintain their supply. This critically appraised topic review describes the recent research trends (since 2010) developed by the world's research communities to reach sustainable methods to recover platinum and palladium from spent catalysts in the liquid phase, namely those involving a solvent extraction (SX) step. The selected recycling processes are based on extensive fundamental research, but this paper intends to focus on information collected about SX procedures applied to real leaching samples of spent catalysts, either from automobile or industrial sources. A critical appraisal of the claimed success levels, the identified constraints, and open challenges is carried out, together with some perspectives on possible ways to redirect research efforts and minimize the gap between academia and industry on this matter.