Conversion of CO₂ in a packed-bed dielectric barrier discharge reactor Available to Purchase

The conversion of CO₂ into CO and O₂ in a quartz cylindrical packed-bed dielectric reactor has been studied using CO₂ and Ar gas mixtures at atmospheric pressure and near ambient temperature with quartz wool, γ-Al₂O₃, and TiO₂ packing. The highest energy efficiencies and conversion rates were observed with TiO₂ packing in 20% CO₂ in Ar: 30% conversion with 2.9% energy efficiency, and 17.5% conversion with 5.0% energy efficiency. Both γ-Al₂O₃ and quartz wool also showed an enhancement in conversion over an unpacked reactor. The percentage of CO₂ to Ar in the range of 20%–60% is shown to have only a minor effect on reactor performance. Conversion as a function of power input and flow rate is studied in detail for γ-Al₂O₃ and TiO₂ packing with similar particle sizes. In both cases, simple chemical kinetic models show that the CO production rate is nearly equal for both materials, while reverse reaction rates to CO₂ are doubled for γ-Al₂O₃ compared to TiO₂. From detailed charge–voltage (Q-V) analysis of all four reactor configurations, it is revealed that the electric field at which discharging occurs is higher for both γ-Al₂O₃ and TiO₂ as compared to the empty or quartz wool filled reactors. Comparing kinetic model results with the electrical Q-V analysis, it appears likely that the higher and similar magnitude electric fields occurring with γ-Al₂O₃ and TiO₂ are directly responsible for the increased CO production rates via increased electron energies in the discharge. The higher reverse reaction rates for γ-Al₂O₃, and its subsequent poorer performance compared to TiO₂, can be attributed to a significantly higher effective surface area, which increases undesirable surface reactions between CO and oxygen species.