(281b) Pressure Swing Redox Processing to Split Water and/or Carbon Dioxide

Thermochemical gas splitting of water and/or carbon dioxide via redox is a promising technology to renewably produce syngas for the diversification of gas-to-liquid (GTL) fuels. Here, a metal oxide intermediate undergoes a two-step redox cycle, where either oxygen or hydrogen and/or carbon monoxide is produced. To date, experimental demonstrations have yet to report efficiencies necessary for competing with conventional technologies, primarily due to the insufficient properties of the active materials considered and the requirement for large temperature swings between redox regimes. As a result, recent research has largely focused on discovering new materials with thermodynamic properties that permit lower temperature operation without sacrificing product yields. However, such efforts have proven difficult, as materials that are reducible at low temperatures often become harder to oxidize (and produce fuel).

In terms of efficiency, performing each reaction at the same temperature is appealing due to the elimination of the significant sensible heating penalties that are associated with conventional temperature swing strategies. Although isothermal operation implies lower hydrogen and/or carbon monoxide yields due to operating the exothermic oxidation reaction under unfavorable conditions, material selection for isothermal shifts to focus on materials that undergo large extents of reaction within the attainable range of oxygen chemical potential.

Here, we evaluate the effect of pressure on the oxidation reaction to overcome the thermodynamic unfavorability of operating isothermally and to eliminate downstream compressive of the product syngas. This is the first study to consider pressurizing the oxidation reaction for water (and/or carbon dioxide) splitting via redox. Results indicate that pressurizing the oxidation reaction can provide a path forward to clean, efficient generation of fuels.