Contaminated hydrogen gas composition and its use as a reference for hydrogen fuels

1 . A hydrogen gas composition comprising the following gas contaminants in the following concentrations in a hydrogen gaseous matrix, expressed in μmol/mol with respect to the total number of moles of gas in the hydrogen gas composition as a whole:

sulphur compound(s): at least 0.002 μmol/mol and at most 0.20 μmol/mol,

formaldehyde (HCHO): at least 0.05 μmol/mol at most 0.50 μmol/mol,

formic acid (HCOOH): at least 0.05 μmol/mol and at most 0.50 μmol/mol,

ammonia (NH 3 ): at least 0.050 μmol/mol and at most 0.50 μmol/mol,

halogenated compound(s): at least 0.020 μmol/mol and at most 0.20 μmol/mol,

the hydrogen gas composition comprising either ammonia (NH 3 ) or formaldehyde (HCHO) but not ammonia and formaldehyde simultaneously.

2 . The hydrogen gas composition according to claim 1 , additionally comprising the following further gas contaminants at the following concentrations in the hydrogen gaseous matrix, expressed in μmol/mol with respect to the total number of moles of gas in the hydrogen gas composition as a whole:

water (H 2 O): at least 2.0 μmol/mol and at most 10 μmol/mol,

oxygen (O 2 ): at least 2.0 μmol/mol and at most 10 μmol/mol.

3 . The hydrogen gas composition according to claim 1 , additionally comprising the following further gas contaminants at the following concentrations in the hydrogen gaseous matrix, expressed in μmol/mol with respect to the total number of moles of gas in the hydrogen gas composition as a whole:

hydrocarbon(s) except methane: at least 0.20 μmol/mol and at most 5.0 μmol/mol),

methane (CH 4 ): at least 0.20 μmol/mol and at most 150 μmol/mol,

helium (He): at least 150 μmol/mol and at most 2500 μmol/mol,

nitrogen (N 2 ): at least 50 μmol/mol and at most 450 μmol/mol,

argon (Ar): at least 50 μmol/mol and at most 450 μmol/mol,

carbon dioxide (CO 2 ): at least 0.50 μmol/mol and at most 5.0 μmol/mol,

carbon monoxide (CO): at least 0.10 μmol/mol and at most 0.5 μmol/mol.

4 . A hydrogen gas composition according to claim 3 , wherein the hydrocarbon(s) except methane comprise or consist of ethane (C 2 H 6 ).

5 . A hydrogen gas composition according to claim 1 , wherein the sulphur compound(s) comprise or consist of hydrogen sulphide (H 2 S) or carbonyl sulphide (OCS).

6 . A hydrogen gas composition according to claim 1 , wherein the halogenated compound(s) comprise or consist of dichloromethane (CH 2 Cl 2 ).

7 . A hydrogen gas composition according to claim 1 , comprising ammonia (NH 3 ) but no formaldehyde (CH 2 O).

8 . A hydrogen gas composition according to claim 1 , comprising formaldehyde (CH 2 O) but no ammonia (NH 3 ).

9 . A metal cylinder containing a hydrogen gas composition according to claim 1 , under a pressure ranging from 20 to 200 bar.

10 . A metal cylinder according to claim 9 , which is an aluminium cylinder, coated aluminium cylinder or stainless steel cylinder.

11 . An aluminium cylinder according to claim 10 , wherein the inner surface of the aluminium cylinder is as obtained through a surface-polishing procedure, and hydrogen sulphide (H 2 S) is present in the hydrogen gas composition.

12 . An aluminium cylinder according to claim 10 , wherein the inner surface of the aluminium cylinder is as obtained by a passivation process producing a film of silicon-based compound(s) on the aluminium substrate, and carbonyl sulphide (OCS) is present in the hydrogen gas composition.

13 . A kit comprising:

one metal cylinder according to claim 9 comprising a hydrogen gas composition and comprising ammonia, and

one metal cylinder comprising a hydrogen gas composition and comprising formaldehyde.

14 . A method for preparing a metal cylinder according to claim 9 comprising the steps of:

(i) optionally pre-treating the inner surface of a metal, preferably aluminium, cylinder by pre-saturating the inside of the cylinder with ammonia (NH 3 ) and/or hydrogen sulphide (H 2 S),

(ii) introducing, into the cylinder obtained at the end of step (i), the gas contaminants providing the set of concentrations,

ammonia (NH 3 ) not being introduced into the cylinder where formaldehyde (HCHO) is present, and vice versa, and

with formaldehyde (HCHO) being introduced into the cylinder before formic acid (HCOOH).

15 . A method according to claim 14 , wherein the pre-saturation of step (i) is maintained during at least 48 hours, with ammonia (NH 3 ) and hydrogen sulphide (H 2 S) concentrations higher than 10 μmol/mol, an aluminium cylinder being used and which is of the type obtained through a surface-polishing procedure.

16 . A method according to claim 14 , wherein the gas contaminants nitrogen (N 2 ), helium (He), argon (Ar), carbon monoxide (CO), carbon dioxide (CO 2 ), methane (CH 4 ), and ethane (C 2 H 6 ), in their maximum individual concentrations, are introduced into the aluminium cylinder in the form of a pre-blended mixture during step (ii).

17 . A method of using a hydrogen gas composition according to claim 1 , comprising using the hydrogen gas composition as a calibration composition and/or quality control composition.

18 . A method of using a hydrogen gas composition according to claim 17 , comprising using the hydrogen gas composition as a calibration composition and/or quality control composition to analyse hydrogen fuel according to the ISO14687: 2019 standard.

19 . A method of using a hydrogen gas composition according to claim 17 , comprising using the hydrogen gas composition as a calibration composition and/or quality control composition to test hydrogen fuel in fuel cells.

20 . A method of using a hydrogen gas composition according to claim 17 , comprising using the hydrogen gas composition as a calibration composition and/or quality control composition for manufacturing hydrogen purifying devices, and preferably filters and hydrogen impurity sensors, in particular for fuel cell electric vehicles (FCEVs) or hydrogen refuelling stations (HRSs).