Production of L-lactate with carbon dioxide fixation by using an enzyme-electrical coupling system

• 1、School of chemistry and chemical engineering, Chongqing University, Chongqing 401331

Abstract：L-lactic acid is one of the 12 basic platform chemicals with significant value.The production of L-lactic acid using carbon dioxide as a raw material can provide a new solution for advancing the development of the carbon peaking and carbon neutrality strategy.Therefore, in this study, carbon dioxide was converted to ethanol by electrocatalytic reduction system, and ethanol was further converted to L-lactic acid by coupled enzyme-catalyzed system.The constructed enzyme-electrically coupled system produced 1.41 mM of L-lactic acid using carbon dioxide as substrate.The reaction conditions of the enzyme-catalyzed system were further explored to find the optimum pH, enzyme concentration and ethanol concentration.The NADH concentration within the enzyme-catalyzed system was also increased by coupling an electrocatalytic cofactor regeneration system to improve the enzyme-catalyzed efficiency. Moreover, the reaction medium of the enzyme-catalyzed reaction was improved by using ionic liquids to increase the carbon dioxide concentration in the system and thus enhance the L-lactic acid production.Finally, an efficient enzyme-electrocoupling system was obtained with an L-lactic acid yield of 4.14 mM, which was three times of the initial yield.

Keywords： Biochemical engineering Enzyme-electrical coupling Carbon dioxide L-lactic acid Ionic liquid