Detection of Impurities in Hydrogen Using Quartz-Enhanced Photoacoustic Spectroscopy

The challenge of reducing the effects of global climate change must involve the path towards the reduction of carbon emission. In this perspective, an important alternative to coal and fossil fuels is represented by hydrogen-related technologies, where hydrogen is used as an energy vector to power fuel cell systems and produce electrical energy starting from electrochemical oxidation of hydrogen. Nevertheless, this technology is not competitive with traditional internal combustion engines due to the strict requirement of pure or purified hydrogen, whose preparation and storage costs are still high. The impurities are generated in the hydrogen production process, such as natural gas steam reforming in which the steam reacts with the natural gas, and their impact on the lifetime of the fuel cell systems is significant, as even trace concentrations of contaminants may lead to relevant degradation of the fuel cell catalyst [1]. The list of damaging impurities in hydrogen includes ammonia (NH3), carbon monoxide, carbon dioxide, sulphur compounds, and hydrocarbons. The analytes concentration in the hydrogen matrix is strongly dependent on the hydrogen production method; however, these contaminants could significantly affect the fuel cell systems operations at concentration level in the range of part-per-million (ppm) and below. Therefore, it is crucial to adopt sensitive and accurate detection methods for online and offline detection of contaminants in hydrogen. Online monitoring techniques allow the detection and quantification of hydrogen impurities on field and in real time, and mainly consist of optical-based techniques.