Identifying Impurities in Hydrogen Fuels - The Essential Role of Inert Coating for Detection of Labile Species

Hydrogen fuel is emerging as a key player in the rapidly growing clean energy market. However, hydrogen can contain impurities (introduced during production, purification and along the hydrogen supply chain) that can limit the efficiency of fuel cells and have led to concerns over pollution. National standard methods, such as ISO 14687, EN 17124, ISO 21087, GB/T 37244 and ASTM D7892 lay out the requirements for testing Hydrogen Fuel Impurities. Common impurities include Hydrocarbons, sulfur compounds, Halogenated compounds and formaldehyde.
It is particularly important to determine the levels of these sulfur compounds to protect expensive catalysts and ensure product quality as sulfur compounds (mainly hydrogen sulfide) can cause permanent deactivation of the catalyst due to the formation of strong metal–S bonds.
However, the determination of sulfur compounds in hydrogen is a challenge because of their highly reactive, adsorptive, and metal catalytic properties. Obtaining reliable and accurate results requires both high inertness throughout the system and high sensitivity analytical conditions.
In this presentation we will review pre-concentration Thermal Desorption technology for robust, reproducible analysis of hydrogen fuel impurities using both ‘On-line’ (directly connected to the hydrogen source) and ‘Off-line’ (grab sampling using sorbent tube, gas bag or canister) sampling strategies. We will show how the use of inert surfaces in the sampling media and internally within the Thermal Desorber ensure the accurate and comprehensive analysis of sulfur species, including hydrogen sulfide down to at least 50ppt. In this way, pre-concentration techniques offer flexibility to couple both to GC-MS for identification of a broad range of analytes including non-targeted compounds, or to use a compound specific detector such as Sulfur Chemiluminescence Detection (SCD) for targeted trace-level analysis.