Adsorption Behaviors of H₂S and CO₂ on the Synergistic Removal of HCl and Hg⁰ in Pyrolytic Waste Plastic Gas on 4Ca-1Co/CA

Abstract

In the pyrolytic waste plastic gas, elements such as chlorine and elemental mercury are contained and need to be removed; meanwhile, different impurity gases may produce an inevitable competitive effect. In this paper, the Ca and Co loaded carbon aerogel (4Ca-1Co/CA) adsorbent was prepared to explore the influence of different impurity gases (H2S and CO2) on the removal performance of HCl and Hg0. H2S, an acid gas, has a competitive adsorption relationship with HCl. H2S would take away the active oxygen species genereated by Co species and form polysulfide polymers (Sn 2–) and SO4 2–, thus reducing the removal efficiency of HCl and Hg0. However, the lower H2S concentration has a weaker influence. In the range of 100 ppm of H2S, the Hg0 removal efficiency decreased to 99% and the HCl removal efficiency decreased to 60%; furthermore, high H2S concentration had an inhibitory effect on the removal of Hg0 and HCl due to the production of a large amount of sulfate covering the active site and blocking the pore. The limiting process of CO2 on the 4Ca-1Co/CA adsorbent is that the formation of CaCO3 reconstructed CaO on the adsorbent surface, and then the destruction of the structure would greatly reduce the removal efficiency of HCl. This paper clarifies the migration paths and influence mechanism of impurity gases, including CO2 and H2S, on the adsorption of HCl and Hg0. It is crucial to further improve the adsorption activity as well as the synergistic control of various gas pollutants in organic solid waste producer gas.