Enzyme-Powered CO₂ Utilization: A Bifunctional Immobilized Biocatalyst for Intensified CCU of Industrial Feedstocks...

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 in situ 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.