Development of an Analytical Method for Sulfur in Hydrogen Gas Using Helium-atmospheric Pressure Pulse Microplasma

In recent years, hydrogen has attracted remarkable attention as an energy vector which will help to reduce the emissions of CO2. According to the international standard (ISO 14687-2), the maximum concentration of sulfur in hydrogen used for fuel-cell vehicles should be lower than 0.004 ppm. In addition, the conventional method, such as gas chromatography, is unsuitable for determining the total sulfur content in hydrogen gas. In this study, a noble analytical instrument utilizing optical emission spectrometry was developed to determine the sulfur content in hydrogen gas. The instrument is composed of a pre-concentration device made of brass, a He-atmospheric pressure microhollow cathode discharge plasma as an excitation source, and a spectrometer. The instrument weights only similar to 2 kg, thus, it is portable. With the presented instrument, only 1.2 L of hydrogen gas is required to investigate whether 0.004 ppm of sulfur is contained or not.