(228r) Integrated Electrochemical-Biological Systems for the Production of Fuels and Chemicals from CO2

One of the challenging processes in producing fuels or chemicals from CO₂ has been efficiently and selectively producing C₄-C₆ and higher multifunctional organic compounds from CO₂. In efforts to overcome these challenges a system that combines the faster kinetics of inorganic CO₂ reduction catalysts with highly selective microbial metabolism is being designed and investigated. It is known that electrochemical synthesis of small molecules which requires only 2-electron reduction steps such as H₂ or formate is able to convert electrical energy into chemical energy with high efficiency. On the other hand, it is also known that certain microbial organisms have the capacity to synthesize higher multifunctional organic compounds from simple C₁ or H₂ precursors with high selectivity but generally have low efficiency. This collaborative research is a unique study of the synergy of novel hybrid microbial-electrochemical platforms for the production of sustainable fuels from CO₂. The initial stage of this research involves the development of an experimental platform which allows for continuous and sustainable electrochemical CO₂ reduction on metal catalysts as well as continuous growth of microbial culture from select products of CO₂ reduction. Methods for the analysis of the products from the electrochemical CO₂ reduction as well the microbial culture has been developed from existing methods which utilize Gas chromatography, H¹NMR, and HPLC. This research involves the design and investigation of three main systems for the integration of electrochemical CO₂ reduction systems and cultures of microorganisms. The first design is focused on coupling these systems via the transfer of the gaseous products CO and H₂ along with unreacted CO₂ to the microbial culture. This was done by using established methods for electrochemical CO₂ reduction and continuous microbial culture growth. The second system design is a further integrated system where the microbial culture and the electrochemical cell is separated via an anion membrane. This is focused on the production of fuels by microorganisms which can metabolize CO₂ reduction products such as formate, while reducing the amount of contamination of the electrode from the microbial culture. The third system to be investigated is a fully integrated system where the electrochemical cell with specific metal catalysts are directly in the microbial culture. This investigation brings together electrochemical engineering and microbial science to utilize the efficiency of electrochemical CO₂ reduction to 2-electron products and the selectivity of specific microorganisms to metabolize these 2-electron products to produce fuels.