Correlating inlet gas composition to conversion efficiency in plasma-assisted landfill gas reforming

The escalating crisis of climate change, driven by the accumulation of greenhouse gases from human activities, demands urgent and innovative solutions to curb rising global temperatures. Plasma-based methane (CH₄) and carbon dioxide (CO₂) reforming offers a promising pathway for carbon capture and the sustainable production of hydrogen fuel and syngas components. To advance this technology, particularly in terms of energy efficiency and selectivity, it is essential to enhance the conversion efficiencies of CO₂ and CH₄. This study focused on atmospheric pressure inductively coupled plasma (ICP) in facilitating this process and focused specifically on inlet gas composition as a key parameter affecting conversion efficiency in the plasma system. We hypothesized that higher volumes of certain landfill gases (specifically CH₄, CO₂, and N₂) would increase CH₄ and CO₂ conversion efficiency due to increased reactant availability, while N₂ would modulate the reaction by acting as an inert buffer gas. A plasma gas reforming dataset, obtained during the operation of a demonstration-scale syngas/methanol production plant, indicated an average methane conversion efficiency of 95.1% and CO₂ conversion efficiency of 30.5%. By applying linear and quadratic regression models, we found that CO₂ flow significantly correlated to CO₂ conversion efficiency in a convex upward trend, characterized by a notable squared term coefficient of 9.757 (p<0.01). CH₄ and N₂ also were significantly correlated with the CH₄ conversion rate (p<0.01). These meaningful results highlight the substantial predictive strength of the models in determining conversion efficiencies based on gas variations and outline improvements that can be made to attain optimal plasma parameters.