Recovering precious metals from proton exchange membrane fuel cells for catalytic application in the thermo-chemical processing of plastic waste

Abstract

Platinum (Pt) serves as a catalyst in proton-exchange membrane fuel cell (PEMFC). Owing to its value, recovery of Pt from PEMFC was motivated. Pt was retrieved as a Pt/C composite through the pyrolysis of a mixed matrix of a membrane electrode assembly (MEA) and a sub-gasket (SG), as part of an environmentally benign methodology. The Pt/C composite was harnessed as a catalyst for the pyrolysis of polypropylene (PP) using CO2 as the reaction medium. Both the one- and two-stage pyrolysis of PP yielded hydrocarbons (HCs) with methyl groups. However, the efficacy of CO2 remains inconclusive for both processes. Upon integration of Pt/C as a catalyst in PP pyrolysis, the chemical species were altered. The major constituents were 4-methylheptane, 2,4-dimethylheptane, p-xylene, and mesitylene. Catalytic pyrolysis of PP using CO2 over a Pt/C composite led to an increased formation of syngas, particularly CO, which is ascribed to the gas-phase interaction between CO2 and volatile matters (VMs) originating from PP. This study demonstrates that the use of a Pt/C composite as a catalyst in the pyrolysis of PP holds promise for the enhanced syngas generation, presenting a prospective avenue for more sustainable and efficient processes.