Determination of Trace Amounts of Sulfur Compounds in Gases by GC-SCD

User Benefits

・ Trace amounts of sulfur compounds can be detected to exceed ISO/DIS 14687 and DIN EN 17124:2019-07 requirements on hydrogen quality for proton exchange membrane fuel ・ Equimolarity of sulfur compounds with GC-SCD allows analysis without individual compound calibration

Introduction

Recent development in proton exchange membrane (PEM) fuel cell research has opened a strong potential for hydrogen gas as fuel, especially used in PEM fuel cells. In this context, tolerances of impurities in hydrogen gas have been reconsidered to fulfill requirementsto be used on catalysts surfaces. In the ISO/DIS 14687 and DIN EN 17124:2019-07, respectively, a quantification limit of 4 ppb total sulfur compounds is defined. Sulfur compounds analysis includes at least the measurement of H₂S, COS, CS₂ and mercaptans. To reach this challenging requirement, a sensitive technique to determine sulfur content is necessary. In this application, we present a valve system for gas sampling connected to a gas chromatograph (GC). Detection was performed with sulfur chemiluminescence detection (SCD). To allow analysis of big sampling volumes (20 mL) for highly volatile compounds, focusing prior to detection was done with a cryogenic cold trap (Frontier Laboratories) by liquid nitrogen cooling. To avoid any adsorption, absorption, and reaction of sulfur compounds, the tubing and valves were Sulfinert^® treated. Calibration standards were prepared from COS stock in the concentration range from 1.3 to 13 ppb. Due to the equimolarity of SCD-2030 a single sulfur compound standard is sufficient.

February 14, 2024 GMT