Adsorption of hydrogen sulfide (H 2 S) on zeolite (Z): Retention mechanism
Résumé
Zeolites are efficient adsorbents for the removal of hydrogen sulfide (H2S) – a trace compound commonly
found in biogas. The assessment of zeolite regeneration potential is an important point to consider before
using them in adsorption processes for biogas treatment. In this study, it was first shown that after
adsorption of H2S, by heating a 13X zeolite at 350 °C, the desorbed quantities of sulfur compounds were
very low. Afterwards, the objective was to understand H2S removal mechanism. Complementary physicochemical
characterizations of the studied zeolite before and after H2S adsorption were performed: specific
surface area, porosity, pH, infrared spectroscopy, thermogravimetry and differential scanning
calorimetry. The speciation of sulfur in the studied zeolite after H2S adsorption was investigated and a
retention mechanism was proposed. It was demonstrated that H2S was converted in elemental sulfur
in the zeolite. This mechanism involves H2S adsorption at the zeolite surface, dissolution and dissociation
of H2S in pore water, and oxidation to form elemental sulfur that can polymerize. The major formation of
elemental sulfur limits the thermal regeneration of the studied zeolite and other regeneration methods
should be considered.