H2 is a clean fuel that can circumvent the dispersed and intermittent nature of renewable energy sources, which limits its current utilization. H2 is converted to the more easily liquefied NH3 for transportation to the point of use where it is decomposed back to H2 sustainably via electrified processes, e.g., dielectric barrier discharge (DBD)-assisted reactors. Catalyst packed beds within the DBD can improve the low energy yields associated with these reactors by selectively facilitating surface reactions and interacting synergistically with the DBD. We studied DBD-assisted NH3 decomposition with zeolites as ordered aluminosilicates, which have reported promising NH3 synthesis energy yields, high dielectric constants to promote DBD-catalyst synergy, plus they are abundant and inexpensive. Specifically, we probed catalyst composition and structure effects on the energy yield by systematically quantifying dilute NH3 decomposition rates and efficiencies within a single-stage, coaxial AC-powered reactor under similar experimental conditions in the presence of different zeolites. We evaluated a suite of MFI samples (X-MFI-Y, where X represents the cation (H+ or NH4+) and Y represents the Si/Al ratio (40 or 25)) as well as LTA (5A) and FAU (13X) to systematically investigate zeolite elemental composition and pore size/structure effects on the H2 energy yield. Steady-state consumption rates on H-MFI-40 trend logarithmically with NH3 feed concentration, similar to the no-catalyst control, yet the rates are higher with the catalyst when controlling for residence time. Future deconvolution of zeolite and bulk DBD contributions to the consumption rate is key for quantifying the overall surface-facilitated reaction kinetics and the underlying DBD-assisted mechanism of NH3 decomposition; this better understanding of the complex interactions in plasma-assisted chemistries is needed to overcome limiting efficiencies in sustainable green H2 production.
