Dry Electrolysis for Recycling CO2 to Renewable Hydrocarbon Fuels and Chemicals

Utilization of CO2 is a requirement for sustainable production of carbon-based fuels and chemicals. Direct electrochemical conversion into simple hydrocarbons and related oxygenates has proven challenging and energetically costly. An alternative is the Boudouard reaction, a thermochemical reaction for upgrading CO2 into valued fuels and chemicals, via the intermediate CO, when combined with renewable hydrogen.  

Varied carbons will be tested including biochar, spent activated carbon and petroleum coke, among others. Carbon materials will be characterized by TEM for structure and probed by chemisorption for active sites as inputs to a structural model for simulations. Experimental CO2 conversion rates and associated activation energies will be compared to atomistic modeling simulations that will include reactive potentials with explicit electronic degrees of freedom, to be developed in the proposed research.

The significance of CO as a product is that it is one component of synthesis gas, commonly referred to as “syn-gas”. The Fisher-Tropsch (FT) process is based on the catalyzed conversion of H2 plus CO to hydrocarbons, suitable for liquid transportation fuels and chemicals. Presently the FT process is practiced at an industrial scale, but uses fossil sources of H2 and CO. There are many forthcoming sources of hydrogen with the primary being electrolysis, driven by renewable sources. Alternative sources include thermo-catalytic decomposition of natural gas (or biomethane) and potentially geological hydrogen. Yet the challenges associated with direct H2 use have prompted high interest in the concept of power-to-liquids (PTL) for converting the H2 generated from renewables into high energy density liquid fuels for transportation sectors, including aviation. (The energy density of liquid fuels is ~ 100x that of Li-ion batteries.) What is needed is a corresponding (sustainable) source of CO that enables the conversion of renewable H2 into hydrocarbon fuels and chemicals via the FT process.  

Within the IEE integrated energy systems theme, this project seeks to advance CO2 recycling into renewable fuels and chemicals. Electrification of the Boudouard reaction will lower the CO2 dissociation barrier, thereby dramatically reducing process temperature while increasing CO2 conversion efficiency into CO. In concert, atomistic simulations will identify charge transfer energetics, advancing mechanistic insights towards decarbonization.