From plastic-waste to H2: Electrolysis of a Poly(methyl methacrylate) model molecule on polymer electrolyte membrane reactors

Hydrogen production by the electrolysis of plastic-waste was recently suggested as an alternative approach to water electrolysis, owing to its favoured thermodynamics. However, the fundamental aspects of such electrocatalytic process were not studied in detail. Here we propose a new approach to understand the electrolysis of polymers, by the use of model molecules. Our target is to develop a technology for the electrolysis of poly(methyl methacrylate), PMMA, plastic waste. We used methyl pivalate (MP) as a model molecule, since it contains similar functional groups than PMMA. We performed electrolysis experiments in a Polymer Electrolyte Membrane reactor with Nafion (R) protonic membranes and Pt/C electrodes at low temperatures (<90 degrees C). The results obtained demonstrated that the electro-oxidation of MP allows to produce H-2 in a range of electrical potentials where water electrolysis is not thermodynamically possible (<1.2 V). The kinetics of this process were studied and a preliminary global mechanism was proposed to explain the electro-oxidative cleavage of this model molecule. We have clearly demonstrated that the electrolysis of a plastic-like model monomer leads to the production of hydrogen. These results could be further extrapolated in view of the practical implementation of this technology for the valorisation of PMMA waste.