Direct Nitrogen Oxides Abatement via Atmospheric Pressure Conventional and Membrane Dielectric Barrier Discharge Plasma

The combustion of carbon-free fuels, such as hydrogen-ammonia blends - promising candidates for long-haul transportation, can result in elevated nitrogen oxides (NO_x) emissions. Dielectric barrier discharge (DBD) plasma reactors offer a compelling non-thermal and non-catalytic approach for dynamic NO_x abatement. In this study, we evaluated the performance of conventional DBD and membrane DBD (mDBD) reactor configurations for the direct decomposition of NO_x. Our results demonstrated that both systems can achieve over 90% NO_x reduction at high plasma power. Notably, under lower power conditions and high flow rates, the mDBD configuration achieves up to 15% higher NO_x reduction compared to the conventional DBD. Species-resolved analysis indicates preferential removal of NO₂ in both configurations, while NO abatement is limited by NO₂ back-reactions that regenerate NO. The improved performance of mDBD under low-power high flow rate conditions is attributed to enhanced micro-discharge activity, driven by radial gas flow that disrupts charge accumulation on the membrane surface, and extended gas residence time in the plasma zone, which increases the likelihood of reduction reactions. These findings highlight the advantages of integrating porous dielectrics into DBD reactors and underscore the need for future research to reduce energy consumption and evaluate membrane durability for practical, real-world plasma-assisted NO_x abatement.