Plasma assisted CO2 dissociation in pure and gas mixture streams with a ferroelectric packed-bed reactor in ambient conditions

Abstract

Carbon dioxide decomposition is a challenging target to combat climate change. Nonthermal plasmas are advantageous for this purpose because they operate at ambient conditions and can be easily scaled-up. In this study, we attempt the CO2 splitting into CO and O2 in a parallel plate packed-bed plasma reactor moderated with Lead Zirconate Titanate (PZT) as ferroelectric component, achieving conversion rates and energy efficiencies higher than those obtained with BaTiO3 in our experimental device. The analysis of the reaction mechanisms with optical emission spectroscopy under various operating conditions has shown a direct correlation between energy efficiency and intensity of CO* emission bands. These results and those obtained with a LiNbO3 plate placed onto the active electrode suggest that high temperature electrons contribute to the splitting of CO2 through an enhancement in the formation of CO2+ intermediate species. Results obtained for CO2 + O2 mixtures confirm this view and suggest that back recombination processes involving CO and O2 may reduce the overall splitting efficiency. The study of mixtures of CO2 and dry air has proved the capacity of ferroelectric packed-bed reactors to efficiently decompose CO2 with no formation of harmful NXOY subproducts in conditions close to those in real facilities. The found enhancement in energy efficiency with respect to that found for the pure gas decomposition supports that new reaction pathways involving nitrogen molecules are contributing to the dissociation reaction. We conclude that PZT moderated packed-bed plasma reactors is an optimum alternative for the decompositon of CO2 in real gas flows and ambient conditions.