High Efficiency CO₂ Conversion in the Rotating Argon Flow using Microwave Plasma at Atmospheric Pressure.

The CO₂ conversion in Ar flow using the microwave plasma was investigated with relatively high power (max. 1.5 kW) 2.45 GHz microwave cavity system at atmospheric pressure. We used small diameter quarts tubing (8 mm, inner radius) as a reactor. At the upstream, the rotating Ar flow was introduced to protect the wall of the reactor tube from the contact of high temperature plasma plume. CO₂ was introduced into the center of the tube by a small nozzle, then mixed with the rotation flow. The maximum conversion efficiency and the energy efficiency were 76.5 % at 95 SCCM of CO₂ and 16.8 % at 6 SLM of CO₂, respectively in 15 SLM Ar rotating flow. In the case of the 6 SLM of CO₂, also we attained 20 % for conversion efficiency at 1.4 kW discharge power. In this study, we obtained comparatively higher efficiencies than that of the latest reported atmospheric pressure plasma systems. The rotating flow may not only protect the quarts wall from the plasma but also confine the plasma plume at near of the center axis that will proceed the decomposition reaction. According to the parameter analysis, we concluded that the higher power to the system, we will get the better conversion efficiency even as in the energy efficiency.