Kinetic Study for Plasma Assisted Cracking of NH: Approaches and Challenges.

Ammonia is considered as one of the promising hydrogen carriers toward a sustainable world. Plasma assisted decomposition of NH could provide cost- and energy-effective, low-temperature, on-demand (partial) cracking of NH into H. Here, we presented a temperature-dependent plasma-chemical kinetic study to investigate the role of both electron-induced reactions and thermally induced reactions on the decomposition of NH. We employed a plasma-chemical kinetic model (KAUSTKin), developed a plasma-chemical reaction mechanism for the numerical analysis, and introduced a temperature-controlled dielectric barrier discharge reactor for the experimental investigation using 1 mol % NH diluted in N. As a result, we observed the plasma significantly lowered the cracking temperature and found that the plasma-chemical mechanism should be further improved to better predict the experiment. The commonly used rates for the key NH pyrolysis reaction (NH + M ↔ NH + H + M) significantly overpredicted the recombination rate at temperatures below 600 K. Furthermore, the other identified shortcomings in the available data are (i) thermal hydrazine chemistry, (ii) electron-scattering cross-section data of NH, (iii) electron-impact dissociation of N, and (iv) dissociative quenching of excited states of N. We believe that the present study will spark fundamental interest to address these shortcomings and contribute to technical advancements in plasma assisted NH cracking technology.