The Role of CH<sub>4</sub> in Plasma-Assisted CO<sub>2</sub> and CH<sub>4</sub> Conversion in a Rotating Gliding Arc Plasma: Insights Revealed by Experiments and Modeling
Senne Van Alphen, Bart Wanten, Fanny Girard‐Sahun, Joachim Slaets, James Creel, Maryam Aghaei, Annemie Bogaerts
Abstract
We investigated the combined conversion of CO 2 and CH 4, so-called dry reforming of methane (DRM), in a rotating gliding arc (RGA) reactor by experiments and modeling for different CO 2 /CH 4 mixing ratios. We obtained the best results at the lowest flow rate (4 L/min) and the lowest amount of CH 4 in the feed gas mixture (25%), reaching a conversion of 22% and 39% for CO 2 and CH 4, respectively, an energy efficiency of 62% and energy cost of 3.25 eV/molecule. A lower energy cost of 2.65 eV/molecule was obtained at 8 L/min. By means of a 3D computational fluid dynamics model, we show that the addition of CH 4 reduces the gas temperature inside the plasma, resulting in slower chemical kinetics, explaining why the least amount of CH 4 (i.e., 25/75 CH 4 /CO 2 ) yields the highest CO 2 and CH 4 conversion. Additionally, the 25/75 CH 4 /CO 2 mixture also displays the highest energy efficiency, due to the high conversion, as well as due the high CO concentration produced in this gas mixture, which is the most beneficial product in terms of energy efficiency. Finally, by means of a quasi-1D chemical kinetics model, we demonstrate that the addition of CH 4 suppresses the CO recombination reactions back into CO 2, after the plasma, as H-based radicals from CH 4 quickly react with O radicals that would otherwise recombine with CO.