Detection of ppb level SO2 in H2 by an adsorption–desorption gas chromatography method

Some H2 impurities (e.g., SO2), even at 10–100 ppb level, can greatly reduce the working life of the proton exchange membrane (PEM) fuel cells. Sulfur compounds such as SO2 is a typical impurity existing in the coal gas derived H2 fuel. As a result, detection of near ppb level SO2 in H2 for fuel cells has been a focus of many recent studies. In this study, we present a gas chromatography (GC) method integrated with an in-house built adsorption–desorption device that can detect SO2 at near ppb level. The technique is as follows: sample gas is collected by a SO2 absorbent at room (or low) temperature, followed by desorption at an elevated temperature prior to gas sampling with GC. Operating conditions are optimized through testing on the absorbent material, adsorption and desorption temperature. Under an optimal condition, a sample gas of 10–20 ppb SO2 was detected within an hour.