Table 5.

Operative conditions and efficiency for NO_x-removal via NTP technology.

Catalytic Removal via NTP Technology
Catalyst Formulation	NTP Technology	Operative Conditions	NOx Removal Efficiency % (Maximum Value Reached)	Reference
Ag/Al2O3	DBD	16–23 kHz, 1–2 W Reacting flow rate: 276 cm3 min−1 NO: 720 ppm Either 540 ppm n-C8H18 or 620 ppm toluene 4.3% O2 7.2% H2O 7.2% CO2 He as carrier gas 1 atm, 25–250 °C	70	[80]
Ag/α-Al2O3	DBD	2 W Reacting flow rate: 2 L min−1 NO: 300 ppm 10% O2 3.2% H2O 265 ppm n-heptane N2 as balance gas	74	[81]
H–MOR Co–MOR NMOR	DBD	5 W Reacting flow rate: 60 mL min−1 NO: 2130 ppm 8% O2 He as balance gas T = 35 °C	99.6	[82]
Co/Ba/Al Pd/Co/Ba/Al Pd particle size = 3.1 nm Pt/Ba/Al Pt particle size = 2.7 nm	DBD	40 kHz, 20 W (in the rich phase) NO: 500 ppm 8% O2 2% H2O 2% CO2 N2 as balance gas T = 150–350 °C	90	[83]
M/Ba/Al (M = Mn, Fe, Co, Ni and Cu)	DBD	0–40 kV, 40 kHz, 1.8 W (in the rich phase) phase) NO: 500 ppm 8% O2 2% H2O Ar as balance gas T = 200–350 °C	100	[84]
Pt/Ba/Al Pt particle size = 2.7 nm Pd/Co/Ba/Al Pd particle size = 3.1 nm Pd/Ba/Al Pd particle size = 3.5 nm	DBD	40 kHz, 1.8 W (in the rich phase) NO: 500 ppm 8% O2 2% H2O Ar as balance gas T = 150–350 °C	99	[85]
Pt/Ba/Al Pt particle size = 2.1 nm Pt/Co/Ba/Al Pt particle size = 1.6 nm Pt/Mn/Ba/Al Pt particle size = 1.8 nm Pt/Cu/Ba/Al Pt particle size = 2.1 nm	DBD	40 kHz, 1.8 W (in the rich phase) NO: 500 ppm 8% O2 2% H2O Ar as balance gas T = 150–350 °C	80	[86]
Zeolites (H–ZSM-5)	DBD	0.03–4 W Reacting flow rate: 66 mL min−1 NO: 1800 ppm 10% O2 He as balance gas 1 atm, 25 °C	97.8	[87]
Cu-modified CMS	DBD	7.6 kV, 8.9 kHz, 200 W Reacting flow rate: 300 mL min−1 0.05% NO 3% O2 N2 as balance gas	96.2	[88]
In/H–BEA zeolite In particle size = 6–10 nm	DBD	0–1.125 W Reacting flow rate: 500 mL min−1 NO: 440 ppm NO2: 14 ppm CH4: 600 ppm SO2: 0–100 ppm 6% O2 7% H2O Ar as balance gas T = 230–570 °C	99	[89]
MnCu/TiO2	DBD–WESP	8 kHz, 10 kV and 200 W SO2: 0–2000 mg·m−3 NO: 200–400 mg·m−3 10% O2 and N2 balancing Reacting flow rate: 4 L min−1 Cleaning water flow rate: 3.6 L min−1 1 atm, 25 °C	93.4	[48]
γ-Al2O3	DBD	7 W NO: 440 ppm NO2: 14 ppm SO2: 460 ppm 21% O2 N2 balancing Reacting flow rate: 600 mL min−1 1 atm, 25 °C	45	[56]
Non-Catalytic Removal Via NTP Technology
NTP Technology	Operative Conditions		NOx Removal Efficiency % (Maximum Value Reached)	Reference
DBD	0–7 kV, 1–2000 Hz		–	[90]
Volume barrier discharge (VBD)	80–500 Hz, 0.56 kW air 30 L min−1 Methane 10 L min−1		90	[91]
DBD	40 kV, 50 Hz NO: 100 ppm SO2: 300 ppm N2 as balance gas		80	[92]
DBD	16 kHz, 40 kV Reacting flow rate: 1 L min−1 NO: 300 ppm 5% O2 N2 as balance gas		77	[93]
DBD	60 kV, 5–25 kHz Reacting flow rate: 10 L min−1 NO: 500 ppm C2H2: 1000 ppm 6% O2 N2 as balance gas		40	[94]
DBD	0–5 kV, 15 kHz, 45 W Reacting flow rate: 1 L s−1 HC: 10 ppm NOx: 116 ppm 3.32% CO2 0.5% CO 17.03% O2		95	[95]
DBD	23 kV, 20 kHz, 250 W Reacting flow rate: 150 L min−1 NO: 350 ppmv SO2: 800 ppmv		88.8	[96]
DBD	0–7 kV, 60 Hz NO: 300 ppm SO2: 0–1000 ppm 4.2% O2 N2 as balance gas		100	[97]