Effect of Hydrophobicity of Ionic Liquids on the Leaching Selectivity of Platinum from a Spent Automotive Catalyst

抄録

Recycling platinum group metals from secondary resources such as spent automotive exhaust catalysts is promising for the circular economy. However, the selective separation of Pt over massive amounts of impurity metals such as Mg and Al is particularly challenging. In this study, non-aqueous direct leaching of platinum from a spent automotive catalyst (SAC) using hydrophobic ionic liquids, namely, trihexyl(tetradecyl)phosphonium chloride (P₆₆₆₁₄Cl) and trioctyl(dodecyl)phosphonium chloride (P₈₈₈₁₂Cl) with the aid of pre-loading hydrochloric acid/hydrogen peroxide was proposed. The more hydrophobic P₈₈₈₁₂Cl exhibited more efficient and selective leaching of Pt over Mg and Al. The recovery of Pt from the metal-loaded P₈₈₈₁₂Cl, and the reusability of the IL for SAC leaching were also demonstrated.