Comparison of the Distribution of H2S-COS at Equilibrium Conditions and Steady-State Conditions in the Synthesis Gas During Passing Through the Empty Column

Abstract

Sulfurous gases in the syngas are pollutants that need to be treated because they cause corrosion on metal surfaces, poisoning of catalysts, and the formation of SOx, an environmental pollutant after the oxidation process. Although there are methods such as the Claus process, scrubbing, and adsorption for the removal of this pollutant, adsorption is the most suitable treatment method for the desulphurization process used in high-temperature gas applications. The major benefit is that gasification, gas cleaning and operation of the downstream process at close temperatures makes the system more efficient and economical. However, due to the presence of CO and CO2, COS formation may occur during the adsorption of H2S to the adsorbents. COS tends to react less on metal oxides (e.g ZnO) compared to H2S. Therefore, the formation of COS reduces the sulfur removal capacity of the adsorbent. In this study, the COS-H2S distribution in the thermochemical equilibrium condition was calculated for each gas component (CO, CO2, H-2, H2O and their mixtures) by using the software Factsage. Afterwards, prepared synthetic syngas compositions (dry and wet) were fed to a laboratory scale adsorption column, and the steady state COS-H2S distribution was measured and compared with the estimated distribution of the software. It has been observed that the COS-H2S distribution trend formed by the synthesis gas in a steady state is similar to the distribution obtained for CO and CO2 binary gas mixtures. It was also observed that there was no significant composition difference between dry and wet synthetic synthesis gas mixtures in the empty column tests.