Evaluation of a Plasma Catalytic-Membrane Dielectric-Barrier Discharge Reactor for Ammonia Synthesis

Ammonia synthesis via nonthermal plasma powered by intermittent electricity from renewable energy sources can be a potentially-transformative technology, especially for point-of-demand operations. We present results of the evaluation of a catalytic membrane Dielectric-Barrier Discharge (mDBD) reactor for the synthesis of ammonia from nitrogen and hydrogen. A porous alumina membrane (with 0.1, 1.0, or 2.0 μm pore size) is used as dielectric barrier and as H₂ gas distributor, allowing greater residence time for N₂ decomposition and greater availability of H₂. The membrane-ground electrode gap is filled with catalyst powder embedded in glass-wool. Three different catalysts are evaluated: nickel, cobalt, and bi-metallic nickel-cobalt, all loaded at 5% by weight on alumina powder (surface area ~ 200 m²/g). We assess the performance of the reactor with electrical, optical, spectroscopic, and FTIR analyses as function of driving voltage. Our results show the role of catalyst properties and design and operation parameters on ammonia production and production efficiency.