Exceeding Equilibrium CO<sub>2</sub> Conversion by Plasma-Assisted Chemical Looping
Evangelos Delikonstantis, Marco Scapinello, Varun Singh, Hilde Poelman, Cesare Montesano, Luca Martini, Paolo Tosi, Guy Marin, Kevin M. Van Geem, Vladimir Galvita, Georgios D. Stefanidis
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.