(684a) Development of a Hydrogen Impurity Enrichment Device Using Pd Alloy Membranes to Support the Growing Hydrogen Economy

Due to the damaging environmental effects of fossil fuels from the transport industry, national and international targets have been set in order to reduce CO₂ emissions. One solution to this problem is the further adoption of fuel cell vehicles which use hydrogen as a fuel source. In the UK it is expected that 1.6 million fuel cell vehicles will be on the road by 2030, with 1,100 hydrogen refueling stations in operation to support this growing sector.

A major problem with fuel cell vehicles is that these systems are extremely susceptible to degradation by impurities. ISO 14687 – 2:2012 specifies the maximum impurity levels of 13 impurities that can be present in fuel cell hydrogen. There is a large analytical challenge associated with validation of the standard, as most impurities are difficult to measure with standard techniques.

A Hydrogen Impurity Enrichment Device has been developed at NPL. Using a Pd-Cu coated Pd-Ag membrane ppm levels of impurities within a hydrogen sample are concentrated to levels where they can be analysed using low-cost equipment. A novel tracer enrichment method was developed which reduced the uncertainty of the measurement by ~60%. It was discovered that a key problem with the accurate of the device was the adsorption or reaction of impurities within the enrichment vessel.

Current work involves optimization of the membrane used and device operating conditions. Tests are underway using binary and ternary Pd alloys manufactured through electroless plating and magnetron sputtering in order to maximise impurity resistance and lower the cost of device, and maximise the enrichment factor.