Contribution of Discharge Excited Atomic N, N₂*, and N₂⁺to a Plasma/Liquid Interfacial Reaction as Suggested by Quantitative Analysis

Abstract

Electric‐discharge nitrogen comprises three main types of excited nitrogen species‐atomic nitrogen (Natom), excited nitrogen molecules (N2*), and nitrogen ions (N2+) – which have different lifetimes and reactivities. In particular, the interfacial reaction locus between the discharged nitrogen and the water phase produces nitrogen compounds such as ammonia and nitrate ions (denoted as N‐compounds generically); this is referred to as the plasma/liquid interfacial (P/L) reaction. The Natom amount was analyzed quantitatively to clarify the contribution of Natom to the P/L reaction. We focused on the quantitative relationship between Natom and the produced N‐compounds, and found that both N2* and N2+, which are active species other than Natom, contributed to P/L reaction. The production of N‐compounds from N2* and N2+ was enhanced upon UV irradiation of the water phase, but the production of N‐compounds from Natom did not increase by UV irradiation. These results revealed that the P/L reactions starting from Natom and those starting from N2* and N2+ follow different mechanisms.

Plasma-driven catalysis: green ammonia synthesis with intermittent electricity

“…A combined plasma-electrolytic system was proposed for ammonia formation from H, generated from either H 2 O molecules or H + ions, by Kumari et al, 205 Hawtof et al, 139 Haruyama et al [206][207][208][209]211 and Peng et al 138,140 Ammonia was formed by direct interaction of air or N 2 plasma with H 2 O, allowing simpler reactors, i.e., no need for counter electrodes in liquids and additional electrolysis. Gorbanev et al 137 used an atmospheric pressure plasma jet with N 2 containing H 2 O vapour, in contact with liquid H 2 O.…”

Towards Green Ammonia Synthesis through Plasma‐Driven Nitrogen Oxidation and Catalytic Reduction

“…Plasma generates highly reactive species which facilitate N 2 fixation, can be operated under atmospheric pressure, and can be powered with renewable electricity, which makes it perfectly suited for decentralized and intermittent production [8] . The recent advances in employing plasma discharges for NH 3 production are related to direct plasma‐driven reaction of N 2 with H 2 , [9] or even using H 2 O instead of H 2 [10, 11] . Plasma‐assisted (e.g.…”

“…[8] Ther ecent advances in employing plasma discharges for NH 3 production are related to direct plasma-driven reaction of N 2 with H 2 , [9] or even using H 2 Oi nstead of H 2 . [10,11] Plasma-assisted (e.g.p lasma-electrochemical [12] and, especially,p lasma-catalytic [9,13] )p rocesses have been proposed to enhance the performance.I np lasma catalysis acatalyst is introduced in the plasma reactor to favor the desired reaction.…”

Direct Oxidative Nitrogen Fixation from Air and H2O by a Water Falling Film Dielectric Barrier Discharge Reactor at Ambient Pressure and Temperature

“…[1] Currently, NH 3 production is primarily dependent on the Haber-Bosch (H-B) process via the N 2 /H 2 reactions mediated by catalysts at high temperatures and pressures; and the demand for HNO 3 is satisfied by catalytic oxidation of H-B-generated NH 3 through the Ostwald process, which however raises energy cost compared with direct oxidative nitrogen fixation ( Figure 1). [1,2] Both of the two processes consume a lot of fossil fuel and have a massive carbon footprint. [3] Therefore, greener and more sustainable routes towards NH 3 and HNO 3 production are actively investigated.…”

“…Recently, atomic nitrogen has also been detected in an atmosphericpressure plasma. [2,12] Plasma-liquid interaction is extremely complex involving gas phase chemistry, multiphase species transport, mass and heat transfer, interfacial reactions and liquid phase chemistry. [19] According to the active N-species as mentioned above in combination with possible reactions previously reported in the literature, a schematic diagram of some of the important species and mechanisms in WF-DBD is shown in Figure 5.…”