Towards sustainable oxalic acid from CO2 and biomass.

To quickly and drastically reduce CO2 emissions and meet our ambitions of a circular future, we need to develop carbon capture and storage (CCS) and carbon capture and utilization (CCU) to deal with the CO-2 that we produce. While we have many alternatives to replace fossil feed stocks for energy generation, for materials such as plastics we need carbon. The ultimate circular carbon feedstock would be CO2. A promising route is the electrochemical reduction of CO2 to formic acid derivatives that can subsequently be converted into oxalic acid. Oxalic acid is a potential new platform chemical for material production as useful monomers such as glycolic acid can be derived from it. This work is part of the European Horizon 2020 project "Ocean" in which all these steps are developed. This review aims to highlight new developments in oxalic acid production processes with a focus on CO2 based routes. We critically assess all available processes and compare them on criteria including overall process efficiency and triple bottom line sustainability.