Adsorption of hydrogen sulfide on graphite derived materials modified by incorporation of nitrogen

Adsorbents for hydrogen sulfide were prepared by heat treatment at 950 °C of spent graphite oxide based materials previously used as ammonia removal media. The materials were characterized using adsorption of nitrogen, potentiometric titration, thermal analysis, FTIR and XRD. The dynamic adsorption experiments showed an enhanced adsorption capacity owing to the presence of basic nitrogen functionalities. Although on the surface of adsorbents hydrogen sulfide was mainly oxidized to elemental sulfur small amount of SO2 was also formed. The removal capacity was found to depend on the dispersion of nitrogen containing species, which is governed by the porosity and structure of the adsorbents. The amount of nitrogen incorporated depends on the amount of ammonia on the surface and on the surface reactivity. The latter is determined by the amount of oxygen containing groups and the level of structural heterogeneity.