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

Authors: 
Antoniuk-Pablant, A., Stanford University
Hahn, C., Stanford University
Jaramillo, T. F., Stanford University
Spormann, A. M., Stanford University
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.
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