Trace Determination of Hydrogen in Coke by Elemental Analysis

FH - HES

Abstract

Recarburizers used in the steel industry are ruthlessly selected according to their quality. One of the critical parameters is the residual hydrocarbon content of the coke or graphite-based products. The current analytical procedure has a detection limit of about 0.2% hydrogen. The dynamic flash combustion of the sample coupled with gas chromatography (GC) was used to develop a simple method for the determination of hydrogen traces in coke. The sample was burned in an oxygen/helium atmosphere at 1020 °C. Separation of the combustion gases, NO2, CO2, H2O, and SO2, is accomplished on a chromatography column and measured by a thermal conductivity detector TCD. A linear response of hydrogen over a concentration range of 98–4910 mg kg?1 with a correlation coefficient of 0.9985 has been achieved. A detection limit of 26 mg kg?1 and a determination limit of 92 mg kg?1 were obtained with new equipment configurations and a sample weight of 8 mg. This corresponds to an impressive improvement of sensitivity of a factor of over 70. The coefficient of variation was found to be 31.3% at a concentration of 98 mg kg?1 and 0.7% at 4910 mg kg?1.