Review of Mid -to High-Temperature Sulfur Sorbents for Application to Desulfurizing Biomass- and Coal-Derived Syngas

This review examines state-of-the-art mid- and high-temperature sulfur sorbents that remove hydrogen sulfide (H₂S) from syngas generated from coal gasification and may be applicable for use with biomassderived syngas. Biomass feedstocks contain low percentages of protein-derived sulfur that is converted primarily to H₂S, as well as small amounts of carbonyl sulfide (COS) and organosulfur compounds during pyrolysis and gasification. These sulfur species must be removed from the raw syngas before it is used for downstream fuel synthesis or power generation. Several types of sorbents based on zinc, copper, iron, calcium, manganese, and ceria have been developed over the last two decades that are capable of removing H₂S from dry coal-derived syngas at mid- to high-temperature ranges. Further improvement is necessary to develop materials more suitable for desulfurization of biomass-derived syngas because of its hydrocarbon, tar, and potentially high steam content, which presents different challenges as compared to desulfurization of coal-derived syngas.