CH₄ and CO₂ valorisation in various non-catalytic plasma reactors. The table is divided into three subsections based on the chemistry of the process.

Feed gas ratio	Reactor setup	SEI [kJ mol−1]	Plasma temperature [K]	Conversion [%]	Products (selectivities [%])	Reference
Non-oxidative methane coupling
5% CH4, 95% N2	DBD AC	1094.4	500	CH4 – 14.8%	C2H6 (10.6%)	77
					C2H4 (0.7%)
					C2H2 (0.8%)
					C-3 (2%)
5% CH4, 95% N2	DBD pulsed	224.64	500	CH4 – 12.4%	C2H6 (6.5%)	77
					C2H4 (0.3%)
					C2H2 (0.3%)
					C-3 (0.9%)
5% CH4, 95% N2	Spark AC	172.8	1000	CH4 – 49.4%	C2H4 (0.3%)	77
					C2H2 (86%)
5% CH4, 95% N2	Spark pulsed	322.56	1000	CH4 – 83.0%	C2H6 (2.6%)	77
					C2H4 (3.1%)
					C2H2 (45.9%)
					C-3 (0.7%)
5% CH4, 95% N2	Rotating arc	61.92	1000	CH4 – 25.8%	C2H6 (0.2%)	77
					C2H4 (1.1%)
					C2H2 (42%)
5% CH4, 95% N2	Gliding arc	72	3000	CH4 – 23.7%	C2H2 (27.2%)	77
5% CH4, 95% N2	Hollow cathode	28.8	2000	CH4 – 42.2%	C2H6 (1.4%)	77
					C2H4 (1.4%)
					C2H2 (27%)
					C-3 (0.3%)
21.2% CH4, 78.8% Ar	Gliding arc, 80 mm length	2090	—	CH4 – 43.4%	C-2 (87.2%)	87
100% CH4	Gliding arc, 20 kHz, 150 mm length	273.6	—	CH4 – 47%	C2H2 (22%)	88
15% CH4, 85% Ar	Gliding arc, 20 kHz, 150 mm length	165.6	—	CH4 – 65%	C2H2 (7%)	88
100% CH4	DBD, 75 kHz, 1 mm gap, 40 mm length	867	—	CH4 – 18%	C2H6 (30%)	90
					C2H4 (3%)
					C2H2 (3%)
					C-3 to C-5 (27%)
100% CH4	Spark, 5 mm gap, 50 Hz DC, 5 kV, pulsed	1059	440	CH4 – 65%	C2H4 (5%)	90
					C2H2 (75%)
					C-3 to C-5 (5%)
100% CH4	Microwave, 1 kHz pulses of 60 μs, 30 mbar	963.5	1500–2500	CH4 – 90%	C2H2 (80%)	93
100% CH4	Corona, 1–2 kHz	3854.1	—	CH4 – 72%	C2H2 (56%)	94
					C4H2 (8%)
					C2H4 (3%)
100% CH4	DBD	4624.9	—	CH4 – 38%	C4H10 (5%)	94
					C2H2 (4%)
					C2H6 (25%)
					C3H8 (10%)
50% He, 50% CH4	DBD, 1.2 mm gap, 120 mm length, 3 kHz	10 350	∼373	CH4 – 18.4%	C2H6 (80.7%)	95
					C2H4 (6.3%)
					C2H2 (1.3%)
					C3H8 (5.3%)
					C-4+ (6.5%)
10% CH4, 90% Ar	DBD, 3 mm gap, 4 mL volume, 10 kHz, 3–6 kV	60	—	CH4 – 13%	—	76
10% CH4, 90% Kr	DBD, 3 mm gap, 4 mL volume, 10 kHz, 3–6 kV	68.57	—	CH4 – 23%	C2H6 (32%)	247
					C2H4 (4%)
					C2H2 (4%)
100% CH4	DBD, 8.8 mL volume, 10 kV, 20 kHz	—	—	CH4 – 55.0%	C2H6 (20.89%)	97
					C2H6 (2.01%)
					C3H6 (12.4%)
					C-4 (11.54%)
					C2H2 (4.85%)
100% CH4	DBD, 20 kHz, 3 mm gap, 13.6 mL volume, 40 kV, 20–50 kHz	1296	—	CH4 – 25.2%	C3H8 (4%)	248
					C2H2 + C2H4 (12%)
					C4H10 (19%)
					C2H6 (34%)
100% CH4	DBD, 0.4 mm gap, 200 mm length, 6.4–8.6 kV	3342	448 (wall)	CH4 – 25.1%	C-2 and C-3 (80.27%)	98
100% CH4	DBD, electrode with disks 5 mm apart	7372.8	—	CH4 – 10.2%	C2H6 (45%)	99
					C3H8 (20%)
					C2H4 (3%)
					C2H2 (3%)
					C-4 (10%)
					C-5+ (12%)
Methane partial oxidation with O 2 , N 2 O or H 2 O
20% O2, 80% CH4	DBD, 1 mm gap, 50 mL volume, 20 kV, 30 kHz, 2 bar	530	353 (wall)	CH4 – 15%	CH3OH (22%)	108
50% H2, 50% O2	DBD, double dielectric barrier	633.6	—	O2 – 90.8%	H2O2 (32.2%)	112
				CH4 – 66.4%	H2O (18.5%)
50% Ar, 42.5% CH4 7.5% O2	DBD, 3.5 mm gap, 17.3 mL volume, 10 ns pulses, 440 Hz, 25 kV	112	—	CH4 – 30%	CH3OH (18%)	113
				O2 – 96%	HCHO (2%)
					C-2 (20%)
5% CH4, 5% N2O, 90% Ar	DBD, 2 mL volume, 1 mm gap	1029	330 (wall)	CH4 – 32.2%	CH3OH (10%)	114
				N2O – 53.8%	HCHO (25%)
					C2H6 (10%)
75% CH4, 25% O2	DBD, 4 mm, 688 cm2 electrode surface	849.6	301 (cooling fluid)	CH4 – 24%	CH3OH (17%)	115
				O2 – 74%	Methyl formate (5%)
					HCOOH (16%)
					HCHO (13%)
					C2H5OH (1%)
80% N2, 10% CH4, 10% O2	DBD, cooled, 1 mm ID, twisted metallic electrode, 75 kHz	672	298 (cooling fluid)	CH4 – 45%	CH3OH (17%)	117
				O2 – 83%	HCHO (3%)
					HCOOH (9%)
50%CH4, 50% O2	DBD, cooled, 1.5 mm ID, twisted metallic electrode, 10 kHz	—	283 (cooling fluid)	CH4 – 12%	CH3OH (10%)	118
					HCHO (15%)
					HCOOH (14%)
50% CH4, 50% air	DBD, 10 kV, 10 kHz, 0.5 mm gap, 600 mm winding spiral ground	864	—	CH4 – 30%	CH3OH (9%)	107
16% CH4, 84% H2O	Capacitively coupled plasma, DC, 133–1333 Pa	345.6	—	CH4 – 5%	CH3OH (20%)	121
					HCHO (6%)
					C2H6 (19%)
50% CH4, 50% H2O	DBD, 2–3 kV, 250–2000 Hz, 1.8 mm ID, 500 Hz pulses of 400 ns	246.4	—	CH4 – 10%	CH3OH (7.5%)	122
				H2O – 5%
CO 2 activation with H 2 , CH 4 or H 2 O
67.4% CH4, 32.6% CO2	DBD, 1.8 mm gap	3600	338 (cooling fluid)	CH4 – 35%	Alcohols (5%)	133
				CO2 – 20%	Acids (5%)
					C2H6 (19%)
					C3H8 (9.3%)
					C-4+ (9%)
67.4% CH4, 32.6% CO2	DBD, 1.1 mm gap, electrode with spacing	3600	338 (cooling fluid)	CH4 – 55%	Alcohols (3%)	133
				CO2 – 37%	Acids (8%)
					C2H6 (14%)
					C3H8 (7.5%)
					C-4+ (8%)
66.8% CH4, 33.2% CO2	DBD, 1 mm gap, 200 mm length, 25 kHz	2400	333 (thermocouple in plasma)	CH4 – 64.3%	CH3COOH (5.2%)	128
				CO2 – 43.1%	Propanoic acid (1%)
					CH3OH (0.3%)
					C2H5OH (1.8%)
50% CO2, 50% H2	Surface discharge, 11 kV, 7 kHz	518.4	—	CO2 – 15%	DME (5%)	134
50% CO2, 50% H2O	Negative corona plasma, 15 kV, 10.2 kHz	6652.8	378 (thermostat)	CO2 – 18%	CH3OH (21%)	136
				H2O – 14%	C2H5OH (13%)