Hydrogen Gas Purifiers for Fuel Cells

Abstract

Abstract:Hydrogen is the most common gas used to operate FCs (fuel cells). The performance of proton exchange membrane FCs is sensitive to the hydrogen gas purity. Of particular concern are specific gaseous contaminants such as carbon monoxide, sulphur compounds, and ammonia that are known to drastically reduce the FC efficiency even when present at low concentrations (in the ppb range). To eliminate efficiency losses due to hydrogen purity, dedicated hydrogen gas purifiers are now available specifically for FCs; their adoption protects the FCs and guarantees that consistent gas purity is supplied throughout their lifetime. Different purification technologies have been developed to match the wide variety of applications and to manage various impurities that are dependent on the H 2 source. For gas sources where nitrogen is present above the acceptable limit, palladium membrane purifiers can be used to reduce the nitrogen concentration to the desired level. At the same time, the other impurities like carbon monoxide, sulphur compounds, ammonia, hydrocarbons, etc. are also removed. For applications where the main concern is the presence of reactive gases, such as carbon monoxide and sulphur compounds, adsorber purifiers can eliminate these impurities down to the single digit ppb range or better. This technology is suitable to cover a very broad range of flow rates, from a few sccm up to 1,000 m 3 /h. The purity performance of both technologies has been proven with state-of-the-art analyzers and will be discussed in the paper.