Optimization of CO2 Conversion in a Cylindrical Dielectric Barrier Discharge Reactor Using Design of Experiments

In this work, a coaxial dielectric barrier discharge reactor has been developed for the decomposition of CO2 at atmospheric pressure. The response surface methodology based on a three-factor, three-level Box-Behnken design has been developed to investigate the effects of key independent process parameters (discharge power, feed flow rate, and discharge length) and their interactions on the reaction performance in terms of CO2 conversion and the energy efficiency of the plasma process. Two quadratic polynomial regression models have been established to understand the relationships between the plasma process parameters and the performance of the CO2 conversion process. The results indicate that the discharge power is the most important factor affecting CO2 conversion, while the feed flow rate has the most significant impact on the energy efficiency of the process. The interactions between different plasma process parameters have a very weak effect on the conversion of CO2. However, the interactions of the discharge length with either discharge power or gas flow rate have a significant effect on the energy efficiency of the plasma process. The optimal process performance-CO2 conversion (14.3%) and energy efficiency (8.0%) for the plasma CO2 conversion process is achieved at a discharge power of 15.8 W, a feed flow rate of 41.9 ml.min(-1) and a discharge length of 150 mm as the highest global desirability of 0.816 is obtained at these conditions. The reproducibility of the experimental results successfully demonstrates the feasibility and reliability of the design of experiments approach for the optimization of the plasma CO2 conversion process.