Exceeding Equilibrium CO₂ Conversion by Plasma-Assisted Chemical Looping

Abstract

We propose and demonstrate an integrated electrified plasma-assisted chemical looping (PACL) process that yields supra-equilibrium CO2 conversions unattainable with conventional catalysis at temperatures ≪3000 K. CO2 is first dissociated inside plasma into CO/O at supra-equilibrium conversions (up to 60%) at a bulk gas temperature of 773 K and a 403 kJ/mol energy cost. Supra-equilibrium CO2 conversions (29% on average) are achieved at the reactor outlet by placing a nanostructured CeO2/Fe2O3 oxygen scavenger, prereduced by H2 plasma, downstream of the plasma zone, to capture produced oxygen species and suppress CO/O recombination. Without plasma-material synergy, such an average CO2 conversion can only be attained at temperatures ≥ 2775 K, according to chemical equilibrium calculations. This concept of plasma-assisted chemical looping allows reaching 3-fold higher conversions than state-of-the-art plasma technologies.