Selective reduction of oxalic acid to glycolic acid at low temperature in a continuous flow process

Abstract

Next to biomass, CO₂ is the only other carbon source to replace fossil feedstocks to produce chemicals and polymers. In a CO₂ fed chemical industry, new platform chemicals will arise. Oxalic acid derived from CO₂ based formate is one of them. It can be converted to a wide array of chemicals including ethylene glycol, or carboxylic acids such as glycolic acid. Glycolic acid is currently a fossil-based monomer used in the production of polyesters. Today the most common route from oxalic acid to glycolic acid proceeds via the oxalic acid di-esters as intermediates and thus requires multiple steps. Recently, we have proven that the direct reduction of oxalic acid to glycolic acid at high yields is possible. In this work, we translate this process into a stable and continuous process using industrially relevant conditions. We lowered the reaction temperature by 25 °C to 50 °C, reduced the reaction time from hours to minutes and proved the catalyst stability over 100 hours using oxalic acid derived from CO₂. This research lays the foundation for an industrial continuous process for the direct reduction of oxalic acid to glycolic acid and opens an important route from CO₂ to chemicals.