Clean H₂ Production by Lignin-Assisted Electrolysis in a Polymer Electrolyte Membrane Flow Reactor

Biomass-derived products, such as lignin, are interesting resources for energetic purposes. Lignin is a natural polymer that, when added to the anode of an alkaline exchange membrane water electrolyser, enhances H₂ production rates and efficiencies due to the substitution of the oxygen evolution reaction. Higher efficiencies are reported when different catalytic materials are employed for constructing the lignin anolyte, demonstrating that lower catalytic loadings for the anode improves the H₂ production when compared to higher loadings. Furthermore, when a potential of -1.8 V is applied, higher gains are obtained than when -2.3 V is applied. An increase of 200% of H₂ flow rates with respect to water electrolysis is reported when commercial lignin is used coupled with Pt-Ru at 0.09 mg cm^-2 and E = -1.8 V is applied at the cathode. This article provides deep information about the oxidation process, as well as an optimisation of the method of the lignin electro-oxidation in a flow-reactor as a pre-step for an industrial implementation.