Continuous measurement of reactive ammonia in hydrogen fuel by online dilution module coupled with Fourier transform infrared spectrometer

Fuel cell electric vehicles hold great promise for a diverse range of applications in reducing greenhouse gas emissions. In power fuel cell systems, hydrogen fuel serves as an energy vector. To ensure its suitability, it is necessary for the quality of hydrogen to adhere to the standards set by ISO 14687:2019, which sets maximum limits for 14 impurities in hydrogen, aiming to prevent any degradation of fuel cell performance. Ammonia (NH₃) is a prominent pollutant in fuel cells, and accurate measurements of its concentration are crucial for hydrogen fuel cell quantity. In this study, a novel detection platform was developed for determining NH₃ in real hydrogen samples. The online analysis platform integrates a self-developed online dilution module with a Fourier transform infrared spectrometer (ODM-FTIR). The ODM-FTIR can be operated fully automatically with remote operation. Under the optimum conditions, this method achieved a wide linear range between (50∼1000) nmol/mol. The limit of detection (LOD) was as low as 2 nmol/mol with a relative standard deviation (RSD, n = 7) of 3.6 % at a content of 50 nmol/mol. To ensure that the quality of the hydrogen products meets the requirement of proton exchange membrane fuel cell vehicles (PEMFCV), the developed ODM-FTIR system was applied to monitor the NH₃ content in Chengdu Hydrogen Energy Co., Ltd. for 21 days during Chengdu 2021 FISU World University Games. The proposed method retains several unique advantages, including a low detection limit, excellent repeatability, high accuracy, high speed, good stability, and calibration flexibility. It is an effective analytical method for accurately quantifying NH₃ in hydrogen, especially suitable for online analysis. It also provides a new idea for the analysis of other impurity components in hydrogen.