NOx production in plasma reactors by pulsed spark discharges

Abstract

Nitrogen fertilizers are important for modern agriculture, among which nitric acid is a basic chemical for ammonium nitrate production. Herein, NOx was produced from N 2 and O 2 using a spark discharge technology with point-to-point and circle-to-plate types of plasma reactors driven by a nano-second pulsed power supply. NOx could be produced with an energy efficiency of 0.09 mol kWh −1 under the gases of 50%/50% N 2 /O 2 , while NO 2 selectivity increased with increasing energy density. The gas temperatures in the spark channels were estimated using the Gibbs free energy equation. Based on kinetics calculations, the reactions of N with O 2 and O with NO were the major reactions for NOx production.

PFAS Degradation in Ultrapure and Groundwater Using Non-Thermal Plasma

“…The formation of ozone and NO x in plasma discharges is commonly reported in the literature [ 31 , 32 , 33 , 34 ]. Significant concentration of O 3 in the gas phase was measured when working with surface discharge.…”

Sustainable nitrogen fixation with nanosecond pulsed spark discharges: insights into free-radical-chain reactions

“…For reactions between the ground and first excited levels in VT and VV transitions (listed in Table 2), we calculate these rate coefficients based on Schwartz-Slawsky-Herzfeld (SSH) theory. Here, the T g is set as 3000 K (estimated using the Gibbs free energy equation adopted from Li et al 21 ) at the maximum current and drops to room temperature rapidly after 2400 ns. The parameter setting of reduced electric field, electron temperature and density are validated by experimental data, including the time-resolved U-I curve and OES diagnosis.…”

“…The FT-IR detected various gaseous products (i.e., NO 2 , NO, N 2 O, N 2 O 4 , HNO 3 ) after the NRP spark discharge. 21,42,53 Fig. 2(a) shows the presence of NO 2 vibrational bands at 1630 cm −1 and 2916 cm −1 , with relatively weak NO at 1900 cm −1 , N 2 O at 2250 cm −1 , N 2 O 4 at 1261 cm −1 , 1763 cm −1 , and 2976 cm −1 and HNO 3 at 1325 cm −1 and 1718 cm −1 .…”

“…6,15,16 Prior to the H-B process, a plasma-based nitrogen fixation approach, namely the Birkeland-Eyde process, was commercialized to convert N 2 and O 2 to nitrates (NO x ) by forming an electrical arc in air. 17 In recent years, various plasma discharge modes have been studied for NH 3 synthesis, including transient spark discharge [18][19][20][21][22][23][24][25] and gliding arc discharge [26][27][28] plasmas, which are attractive for their reasonable energy efficiency (the best energy efficiency reported to be ∼32 kW h kg −1 ) and the ability to be used along with the common electrocatalytic processes, 6,15,16 though the energy efficiency is still inferior to the H-B process. 2,18 The transient spark discharge is usually triggered by a nanosecond repetitive pulse (NRP) power source [29][30][31][32][33][34][35][36][37][38][39][40] to effectively restrain the spark-to-arc transition by the short pulse voltage.…”

“…From an economic point of view, the transient spark discharge device is compact in size, low in cost, and easy to scale up. During the discharge, the spark channels can be quickly formed and maintained for a long time, and the active species (i.e., electrons, vibrational-state molecules and free radicals) 29 and the gas temperature (T g , ∼3000 K) 21 in these discharge channels have been found suitable for nitrogen oxidation reactions (1) and (2). 41,42…”