Toward the Recovery of Platinum Group Metals from a Spent Automotive Catalyst with Supported Ionic Liquid Phases

We present a novel approach for the separation and recovery of Pt and Pd leached from a spent automotive catalyst relying on conventional and polymerized supported ionic liquid phases (SILPs and polySILPs, respectively). A variety of parameters with possible effects on the separation behavior, namely, acidity and concentration of the platinum group metal (PGM) containing solution, as well as different SILP and polySILP loadings, were evaluated for the separation of PGMs in the presence of high concentrations of Al, Fe, Zn, and Ce. The polySILP material demonstrated the ability to separate the PGMs from major accompanying interferences in a single separation step, while problems arising from ionic liquid leaching in the case of SILPs could be avoided. Moreover, the use of supported ionic liquid phases allowed the drastic reduction of the amount of required ionic liquid compared to conventional liquid-liquid separation, while avoiding problems arising from emulsion formation. Subsequent stripping experiments lead to further purification of the PGMs and finally desorption from the solid material into a pure solution. Eventually, the concept of chemisorbed polySILPs provides a new and convenient approach for the recycling of platinum group metals.

Automated summary

The polySILP material showed the capability to separate PGMs from major accompanying interferences in a single separation step, while avoiding problems arising from ionic liquid leaching in the case of SILPs. The use of supported ionic liquid phases allowed a significant reduction in the amount of required ionic liquid compared to conventional liquid-liquid separation, while preventing issues related to emulsion formation. Subsequent stripping experiments further purified the PGMs and facilitated their desorption from the solid material into a pure solution, illustrating a new and convenient approach for recycling platinum group metals through the concept of chemisorbed polySILPs.