Environmental assessment of proton exchange membrane fuel cell platinum catalyst recycling

International audience

A proton exchange membrane (PEM) fuel cell, an alternative to combustion processes that consume fossil resources, is used to convert energy stored in the form of hydrogen into electricity. The membrane-electrode assembly (MEA), the core of this system, contains platinum, a noble metal, which is a limited resource. This paper presents an environmental assessment of a recycling process for the platinum catalyst contained in the MEA of a PEM fuel cell. During this study, four hydrometallurgical platinum recovery processes from Pt/C particles have been developed at the laboratory scale. The considered process alternatives are composed of the four following steps: leaching, separation, precipitation and filtration. Approximately 76% of the platinum can be recovered as [NH4]2PtCl6 salt using the most efficient process alternatives. In this case, platinum leaching is carried out with a mixture of H2O2 and HCl, followed by liquid/liquid platinum extraction and a precipitation step.The environmental assessment was performed using the SimaPro 8 tool coupled with the EcoInvent 3.1 database. The environmental impacts were estimated for a 25 cm2 active area MEA considering the production and end-of-life stages of the MEA life-cycle using the CML-IA baseline V3.02 method. The results show that more than half of the main impacts of the MEA life-cycle can be avoided for four relevant impact categories if platinum is recovered in the end-of-life of the product.