Anion Exchange Membrane Electrolyzers as Alternative for Upgrading of Biomass-Derived Molecules

Upgrading of biomass-derived platform molecules to fuels or chemicals provides a unique alternative for the substitution of fossil sources with renewables. Electrochemical reduction (ECR) is one of the upgrading technologies, alternative to catalytic reduction, which only requires electricity as the energy input and can be powered by carbon free energy sources. Moreover, ECR does not require external addition of hydrogen, as this can be generated in situ. In this work, an anion exchange membrane (AEM) membrane electrode assembly (MEA) has been tested for the efficient reduction of biomass derived molecules and compared with a cation exchange membrane (CEM) MEA. The cathode electrocatalyst has been modified with the addition of hydrophobicity and anion exchange ionomers and incorporated onto an anion exchange membrane. Electrochemical experiments were performed with a metal free electrocatalyst in the presence and absence of surrogate compounds. The results showed that changes in the catalyst formulation can increase the overpotential for the competing hydrogen evolution reaction (HER), while significantly enhancing the reduction of the organic molecules. Bulk electrolysis experiments demonstrated higher efficiencies for furfural ECR in AEM-MEA vs CEM-MEA, reaching conversions up to 94% at 50 mA cm(-2) and in the absence of a supporting electrolyte. Moreover, AEM-MEA was able to facilitate water management during the reduction process and contribute to the separation of small carboxylic acids.