Abstract
The quality assurance of hydrogen fuel for mobile applications is assessed by the guidelines and directives given in the European and international standards. However, the presence of impurities in the hydrogen fuel, in particular nitrogen, water, and oxygen, is experienced in several refueling stations. Within this work, metal-organic framework (MOF)-based membranes are investigated as a fine-purification stage of the hydrogen fuel. Three H2/N2 concentrations have been used to analyze the separation factor of UiO-66-NH2 membranes prepared using the layer-by-layer (LBL) and the one-pot (OP) synthesis methods. It is shown that the separation factor for an equimolar ratio is 14.4% higher for the LBL sample compared to the OP membrane, suggesting a higher orientation and continuity of the LBL surface-supported metal-organic framework (SURMOF). Using an equimolar ratio of H2/N2, it is shown that selective separation of hydrogen over nitrogen occurs with a separation factor of 3.02 and 2.64 for the SURMOF and MOF membrane, respectively. To the best of our knowledge, this is the highest reported performance for a single-phase UiO-66-NH2 membrane. For higher hydrogen concentrations, the separation factor decreases due to reduced interactions between pore walls and N2 molecules.
Highlights
For sustainable mobility, the European Commission considers that hydrogen will account by 2050 for 32% of the total fuel mix in the European transport sector [1]
In order to extend the performance and lifetime of the PEM fuel cell, the hydrogen fuel delivered at the nozzle must satisfy the Directive on Alternative Fuels Infrastructure (DAFI, Directive 2014/94/EU) and European (EN 17124:2018) as well as international
This study aims to investigate the potential of metal-organic framework (MOF)-based membranes to separate nitrogen impurities from hydrogen gas
Summary
The European Commission considers that hydrogen will account by 2050 for 32% of the total fuel mix in the European transport sector [1]. To achieve these targets, the employment of fuel cell light- and heavy-duty vehicles must be expanded as well as the necessary infrastructure, in particular the network of hydrogen refueling stations (HRSs). Between the production site (being off-site or on-site) and the nozzle, there is a long way where impurities can contaminate the hydrogen fuel during the production process, during transportation to the hydrogen station, or during the refilling process, including compression. That’s why, to ensure the quality of gaseous hydrogen fuel at the nozzle, four normative references, ISO-14687:2019, 19880-1, 19880-8:2019, and 21087, provide guidelines and directives to achieve the quality assurance of hydrogen in mobility applications
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