Measurement and Testing Table 2: Stability of NMTHC measurement with injection of benzene standard. Sampling date


10/12/2020 08:40 10/12/2020 12:41 10/12/2020 16:42 10/12/2020 20:43 11/12/2020 00:44 11/12/2020 04:45 11/12/2020 08:46 11/12/2020 12:11 Mean


Standard deviation RSD in %


Nber of measurements Period in hours


Concentration (ppb(v))


1128.32 1090.11 1067.32 1071.31 1070.31 1081.29 1084.30 1053.88 1080.86 22.24


2.06% 8


Retention time (s)


38.67 38.75 38.65 38.67 38.55 38.60 38.63 38.63 38.64 0.06


0.15% 8


Figure 1: Chromatogram obtained on auto-GC-FID for Methane and NMTHC measurment


3 Results and Discussion Here are described the three analytical methods for the characterization of hydrogen impurities. 3.1 Total hydrocarbon measurement The system allows the separation of H2


, O2 , N2 and CO2 from methane and NMTHC.


Chromatogram obtained on the system can be seen in the Figure 1 (acquisition starts after the elution of permanent gases). Therefore, the system can quantify trace-level impurities in hydrogen after being calibrated with classical cylinder which uses N2


as balance gas.


The relative standard deviation on benzene for 8 measurements performed over 24h is 2.06% (Table 2) and the low detection limit (LDL) is 50 ppb for methane and 20 ppb for NMTHC (eq benzene).


3.2 CO and CO2 measurements


2-Dimensional gas separation is required for the analysis of CO and CO2 into a Porapak Q column to separate CO2


. First the sample is injected from the permanent gases. Then the permanent gases


will be injected into a 5A molecular sieve column to separate and analyze CO. For both molecules, a catalytic system (Methanizer, Chromatotec®


, France) will reduce CO and CO2 to CH4 under


hydrogen at 400°C before quantifi cation with the FID. The cycle time is 10 minutes and the LDL is less than 10 ppb (200 ppb is the maximum required in the ISO 14687).


3.3 Formaldehyde and formic acid measurements


Following the reference ISO 16000-3 method, formaldehyde can be quantifi ed from few ppt to ppm level depending on the sampling volume. For measurement at ppb level, 60 L of the sample is required (1h sampling). Typical chromatogram is shown in the Figure 2. Formaldehyde (elution at 242 s) is perfectly separated from acetaldehyde (elution at 272 s).


This technique is very sensitive and powerful for the characterization of aldehydes, ketones and formic acid but it is not fully automatic as it requires trained people for the elution of DNPH cartridges [7]. A new automatic sampling DNPH system is currently developed in collaboration with ICPEES (CNRS, France) and should be available soon [9], [10]. Also, for formaldehyde and acetaldehyde, auto-GC-FID system can be used with LDL below 1 ppb and cycle time of 15 minutes without interferent [9].


4 Conclusion


In this article, we present a cost-effective and fully automatic turnkey solution for the measurement of trace level impurities in hydrogen where all results are listed in a dedicated software. A combination of several analytical techniques and methodologies are necessary to perform the full scope but it can be done automatically using industrial automatic gas chromatograph systems.


5 Bibliography


[1] H. Meuzelaar, J. Liu, S. Persijn, J. van Wijk, and A. M. H. van der Veen, « Trace level analysis of reactive ISO 14687 impurities in hydrogen fuel using laser-based spectroscopic detection methods », Int. J. Hydrog. Energy, vol. 45, no 58, p. 34024-34036, nov. 2020, doi: 10.1016/j.ijhydene.2020.09.046.


[2] « European Parliament - News CO2 emissions from cars: facts and fi gures (infographics) », March 3rd


2019. https://www.europarl.europa.eu/news/en/headlines/society/20190313STO31218/co2-emissions- from-cars-facts-and-fi gures-infographics.


[3] European Commission and Directorate-General for Research and Innovation, Final report of the High-Level Panel of the European Decarbonisation Pathways Initiative. Publications Offi ce, 2018. doi: 10.2777/476014.


[4] X. Zhang et al., « Infl uence of Formic Acid Impurity on Proton Exchange Membrane Fuel Cell Performance », J. Electrochem. Soc., vol. 157, no 3, p. B409, 2010, doi: 10.1149/1.3284646.


[5] « ISO 16000-3:2012 - Indoor air - Part 3: Determination of formaldehyde and other carbonyl compounds in indoor air and test chamber air - Active sampling method ».


[6] C. Beurey et al., « Review and Survey of Methods for Analysis of Impurities in Hydrogen for Fuel Cell Vehicles According to ISO 14687:2019 », Front. Energy Res., vol. 8, 2021, Available on: https://www. frontiersin.org/article/10.3389/fenrg.2020.615149


[7] S. Uchiyama, E. Matsushima, S. Aoyagi, et M. Ando, « Simultaneous Determination of C1−C4 Carboxylic Acids and Aldehydes Using 2,4-Dinitrophenylhydrazine-Impregnated Silica Gel and High- Performance Liquid Chromatography », Anal. Chem., vol. 76, no 19, p. 5849-5854, oct. 2004, doi: 10.1021/ac0493471.


[8] S. Christophe et al., « Determination of the argon concentration in ambient dry air for the calculation of air density », Metrologia, vol. 44, p. 448-452, Dec. 2007, doi: 10.1088/0026- 1394/44/6/003.


[9] M. Mascles, A. Grandjean, S. Le Calvé, D. Bazin, and F. Amiet, « Development and comparison of three analytical systems for detection and quantifi cation of formaldehyde and other aldehydes for process, indoor and ambient air emissions ». September 2021. Available on: https://hal.archives- ouvertes.fr/hal-03577223


[10] A. Grandjean, « Développement de méthode d’analyse microfl uidique pour la quantifi cation de formaldéhyde dans l’air ». http://www.theses.fr/s274189.


Figure 2: Chromatogram obtained for the injection of 13 aldehydes / ketones mixture


29


Author Contact Details Damien Bazin and Jean-Philippe Amiet, Chromatotec • 15 Rue d’Artiguelongue - Saint-Antoine 33240 VAL DE VIRVEE – France • Tel: +33 557 940 626 • Email: info@chromatotec.com • Web: www.chromatotec.com


Damien Bazin Jean-Philippe Amiet


WWW.PETRO-ONLINE.COM


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