Electrocatalytic oxidation of biomass-derived furans to 2,5-furandicarboxylic acid - A Review

Abstract

Electrocatalytic conversion of biomass will become necessary for achieving sustainable production of many kinds of chemicals. In this review, conversion of 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA) via electrochemical oxidation is considered. Transition metal-based catalysts (e.g. Ni) exhibit an optimal balance of activity and selectivity. However, issues such as low stability and insufficient active sites hinder electrocatalytic efficiency of HMF to FDCA. Enhancements can be achieved through controlling catalyst morphology and particle size, heteroatom doping (N, S, P), crystal structure regulation, and defect/vacancy creation. The design of the electrolytic cell is critical to the stability of electrocatalytic oxidation of HMF, and the membrane electrolytic cell (MEA) combined with feed separation can reduce HMF conversion to other side-products (e.g. <10 % humins) at high HMF concentrations (100 mM) in alkaline electrolyte (1M KOH). Coupling the electrocatalytic oxidation of HMF with reduction reactions (e.g. hydrogen evolution reaction, nitrogen reduction reaction) can achieve up to twice the energy efficiency improvement, and developing bifunctional electrocatalysts can balance the potentials and electrocatalytic rates of the cathode and anode. Using organic solvents (e.g. methanol or isobutanol) and controlled temperatures (393 to 413 K), FDCA (> 90 %) can be effectively separated and purified at production rates of up to 33000 tons/year being feasible with present technology. The stability of electrolytic systems at high current densities is of great significance for industrial applications. Increasing electrode area or modifying the coordination bonds of the sites can help to debottleneck issues associated long operation hours at large current densities.