The impact of hydrothermally etched and ceria-coated soda-lime glass beads on CO2 reduction in a packed-bed dielectric barrier discharge plasma reactor

Abstract

Carbon Capture and Utilization (CCU) provides a complementary solution to renewable energy technologies, such as solar, wind, and hydropower, to reduce CO2 emissions. It involves extracting CO2 from emission sources and converting it into valuable materials and fuels.1-4 An emerging approach for converting CO2 into value-added chemicals and fuels is plasma-catalytic reduction using a non-thermal plasma discharge.5 The non-thermal plasma, such as a dielectric barrier discharge (DBD) reactor, provides energy to dissociate and reduce CO2 molecules into products such as CO, and in the presence of an additional hydrogen source (e.g., CH4, H2, H2O), alkanes, alkenes, alkynes, alcohols, aldehydes, and ketones in a single-step process.5-7

Many interacting factors affect the CO2 conversion and energy efficiency in plasma reactors. While temperature, pressure, and reactor geometry play a role, packing with suitable (dielectric) materials and catalysts has shown promise to considerably improve performance through synergistic effects with the plasma discharge.8 Nevertheless, the impact of the material properties on the plasma performance is not yet fully understood.

Limited research correlates the diverse outcomes of CO2 conversion (conversion degree, energy efficiency, and selectivity) with selectively altered material properties while keeping other material properties constant. To bridge this gap, our study aimed to alter/activate the surface characteristics of soda-lime glass packing material (i.e., beads) through hydrothermal etching. In addition, to examine the impact of a ceria coating on the plasma-catalytic CO2-splitting reaction, we deposited cerium cations onto the activated soda-lime glass surface to produce the coating. The fundamental properties that make ceria attractive as a catalyst include its high oxygen storage capacity and oxygen vacancy formation ability.9 Oxygen vacancies in the ceria lattice are hypothesized to promote reactivity towards the CO2 plasma species.

This study concludes that increasing the surface roughness of soda-lime glass packing material in a DBD reactor reduces the degree of CO2-splitting. However, applying a ceria coating on top of this activated packing material improves the reduced conversion of CO2.

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