Enzyme-Powered CO ₂ Utilization: A Bifunctional Immobilized Biocatalyst for Intensified CCU of Industrial Feedstocks to High-Value Chemicals

Decarbonizing industry demands a shift from high-energy fossil carbon to more sustainable green processes that valorize CO₂ as a waste product. In this context, biocatalysis offers a promising approach for integrating Carbon Capture and Utilization (CCU) with the conversion of industrial waste into value-added chemicals. To facilitate the transition from bench-scale experiments to industrial-scale CCU, enzyme immobilization plays a crucial role by enhancing biocatalyst stability, reuse, and overall reaction efficiency. This study explores an industrially relevant multienzyme CCU platform to valorize CO₂ and glycerol by developing a bifunctional biocatalyst through a one-step sequential purification/coimmobilization strategy using formate dehydrogenase (FDH) and glycerol dehydrogenase (GlyDH) for the coproduction of formate and dihydroxyacetone (DHA), with <i>in situ</i> cofactor regeneration. The obtained biocatalyst was optimized for stability and activity, and its performance was first evaluated using pure substrates, as well as under industrially relevant conditions with a crude gas mixture mimicking emissions from iron and steel industry and crude glycerol from biodiesel production. The results demonstrate the feasibility of this system for sustainable CO₂ conversion, achieving the highest formate concentrations reported to date via enzymatic catalysis, 50.4 ± 0.3 mM (2.3 g L^-1). Similarly, the valorization of crude glycerol into DHA was achieved, along with glycerol carbonate as a byproduct. The biocatalyst-enabled reaction intensification with significant yields for all products improved stability and reusability over five reaction cycles and reduced inhibition. The successful production of three high-value molecules was achieved through a CCU approach aimed at the valorization of industrial waste.