Chemoadsorption for Separation of Hydrogen Sulfide from Biogas with Iron Hydroxide and Sulfur Recovery

Hydrogen sulfide (H2S) removal from biogas is essential to allow biogas storage in the natural gas grid. Several established methods exist, most of them making use of non‐reusable substrates such as iron sponge or active carbon. Coated metallic foams provide a reusable sustainable alternative. Several iron oxides and hydroxides were tested to validate the H2S adsorption properties before and after thermal regeneration, i.e., sulfur removal. Amorphous iron hydroxide proved to efficiently clean biogas after maximum four sulfur removal cycles and showed an almost ten times larger capacity for sulfur adsorption than crystalline hematite Fe2O3. Very low H2S contents could be realized until breakthrough. New materials for a regenerable biogas desulfurization system were developed in the project "SuRIOx" . The adsorber materials contain metal foams as carrier and iron sorbent. The functionality of the particular process steps desulfurization, in situ adsorber reactivation, and thermal ex situ adsorber regeneration including sulfur recovery could be demonstrated in labscale tests.