Abstract: Thermal plasma-driven dry reforming of methane (DRM) has gained increased attention in recent years due to its high conversion and energy conversion efficiency (ECE). Recent experimental work investigated the performance of a pure CO<sub>2</sub>plasma with post-plasma CH<sub>4</sub>injection. The rationale behind this strategy is that by utilizing a pure CO<sub>2</sub>plasma, all plasma energy can be used to dissociate CO<sub>2</sub>, while CH<sub>4</sub>reforming proceeds post-plasma in the reforming reactor with residual heat, potentially improving the energy efficiency compared to injecting both CO<sub>2</sub>and CH<sub>4</sub>into the plasma. To assess whether post-plasma CH<sub>4</sub>injection indeed improves the DRM performance, we developed a chemical kinetics model describing the post-plasma conversion process. We first validated our model by reproducing the experimental results of the pure CO<sub>2</sub>plasma with post-plasma CH<sub>4</sub>injection. Subsequently, we compared both strategies: injecting only CO<sub>2</sub>inside the plasma while injecting CH<sub>4</sub>post-plasma,<italic>vs.</italic>classical plasma-based DRM. Our modeling results indicate that below specific energy inputs (SEI) of 220 kJ mol<sup>−1</sup>, the total conversion slightly improves (<italic>ca.</italic>5%) with the first strategy. However, the ECE is slightly lower due to the low H<sub>2</sub>selectivity caused by substantial H<sub>2</sub>O formation. The highest conversion and ECE are obtained at SEI values of 240–280 kJ mol<sup>−1</sup>, where both strategies yield nearly identical results, indicating the limited potential of improving the performance of DRM by pure CO<sub>2</sub>plasma with post-plasma CH<sub>4</sub>injection. Nevertheless, the approach is still very valuable to allow higher CH<sub>4</sub>/CO<sub>2</sub>ratios without problems of coke formation within the plasma, and thus, to improve plasma stability and reach higher syngas ratios, which is more useful for further Fischer–Tropsch or methanol synthesis.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 9.8
DOI: 10.1039/D4GC02889A