(550b) Role of Amine Structure on Hydrogen Sulfide Capture from Dilute Gas Streams Using Solid Adsorbents

The hydrogen sulfide composition in biogas ranges from 0-5% depending on the feed source to the biogas digester. To meet renewable natural gas specifications of 0-4 ppm H₂S content, technologies that remove H₂S from raw biogas feeds are needed. This contribution assessed three similar adsorbents with similar textural and physical properties, but with different amines grafted to the surface. Specifically, materials containing primary, secondary and tertiary amines at the end of a propyl surface linker grafted on a silica support are explored. H₂S adsorption isotherms and cyclic studies are presented for these materials and it is shown that secondary amines have the best amine efficiency while tertiary amines are the most stable for H₂S capture, of the materials studied. The results suggest the consideration of secondary and tertiary amines for the design of amine adsorbents suitable for H₂S removal in dilute gas streams over multiple cycles.