Recovery of Palladium from Spent Catalysts—A Critical State-of-the-Art Review

The high economic value and unique technological properties of the platinumPlatinum -group metals (PGMs), plus their growing scarcity in the Earth’s crust, justify the crucial importance of developing recyclingRecycling practices for PGMs end-of-life materials. Examples of top devices relying on the use of PGMs are automotive and industrial catalysts, and electrical and electronics equipment. This article critically describes the most recent research on the use of solvent extractionSolvent extraction to recover one PGM, palladiumPalladium , from spent catalystsSpent catalysts . Some groups focus on the development of schemes involving commercial extractants, while others prefer to design specific molecules to efficiently and selectively recover palladiumPalladium from these particular complex leachingLeaching solutions. Examples of commercial extractants proposed for the former schemes are Alamine® 308, TBP and LIX® 84I; while on the other hand, sulfurSulfur -containing diamides, thioamides, thiocarbamates, and dithioethers have recently been developed. Ionic liquids have to be mentioned too.