Cell-Free CO₂ Valorization to C6 Pharmaceutical Precursors via a Novel Electro-Enzymatic Process

Abstract

The healthcare industry emits significant amounts of CO2 and has an imperative need for decarbonization. This study demonstrated a new hybrid electro-enzymatic process that converts waste CO2 into high-value C6 pharmaceutical precursor compounds. A novel three-chamber electrolyzer equipped with a Cu-based gas diffusion electrode converted gaseous CO2 into ethanol at a high current density (40–60 mA/cm2), high selectivity (43–81 mol %), and production rate (368–428 mg/L/h). Purified ethanol from the electrolyzer was then sent to an enzymatic bioreactor where ADH and DERA enzymes upgraded ethanol into C6 statin precursor molecules at high yields (29–35%) via acetaldehyde. Competitive C6 lactol synthesis rates (4.7–5.7 mM/day) and titers (712–752 mg/L) were achieved, demonstrating the potential of the end-to-end process. The C6 lactol product can seamlessly be converted to statins, a class of lipid-lowering medication that is among the largest selling class of drugs in the world. This hybrid process provides a new pathway for CO2 valorization to high-value products and accelerates healthcare sector decarbonization.