Table 2.

General syngas application and related cleaning requirements (Dayton et al., 2019, Ephraim et al., 2020, Prabhansu et al., 2015, Richardson et al., 2015, Woolcock and Brown, 2013).

Contaminant	Syngas application
	Steam cycle power station	Gas engine	Gas turbine	Solid oxide fuel cell	Molten carbonate fuel cell	Proton exchange membrane fuel cell	Methanol synthesis	Fischer-Tropsch synthesis
Particles	Minimal requirements	<50 mg/Nm3	<30 mg/Nm3	<1 ppmw	<0.01 nm	n.d.	<0.02 mg/Nm3	<0.5 mg/Nm3
Tar	Of no importance, but condensation must be avoided	<100 mg/Nm3	<50 mg/Nm3	Several tens to few hundred ppmv	<2000 ppmw	<100 ppmv	<0.1 mg/Nm3	<1 ppmv
Sulfur (H2S, COS)	Final SOx emissions limited by regulation	Final SOx emissions limited by regulation	<20 ppmv	Few ppmv	<0.1 ppmv (H2S)	<1 ppm	<1 mg/Nm3	<0.01 ppmv
Nitrogen (HCN, NH3)	Final NOx emissions limited by regulation	Final NOx emissions limited by regulation	<50 ppmv	n.d.	<0.1 ppmw (HCN) <1%vol (NH3)	n.d.	<0.1 mg	<0.02 ppmv
Alkali (primary K and Na)	n.d.	n.d.	<0.02 ppmv	1 ppmv	n.d.	n.d.	n.d.	<0.01 ppmv
Halides (primary HCl)	n.d.	n.d.	<1 ppmv	Few ppmv	<0.1 ppmw	n.d.	<0.1 mg/Nm3	<0.01 ppmv
Heavy metals	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	<0.001 ppmv

n.d. = not detected