Strategies for Alleviating Sulfur Poisoning in Methane Steam Reforming Catalysts

Feedstock derived from natural gas often contains sulfur compounds such as hydrogen sulfide (H₂S), sulfur dioxide (SO₂), carbon disulfide (CS₂), mercaptans, and thiophenes if not subjected to thorough desulfurization treatment. In methane steam reforming, H₂S emerges as the primary sulfur compound, with different sulfur compounds causing catalyst poisoning via distinct pathways. Throughout the reforming process, the generation of high-temperature water vapor or hydrogen prompts the conversion of most sulfur compounds to H₂S, which subsequently adsorbs onto active sites, resulting in catalyst poisoning. Thus, H₂S stands as the main culprit, triggering deactivation mechanisms like sulfidation of active components and accelerated carbon deposition.

Researchers like Fumihiro have explored the use of noble metals such as Rh, Pt, Ir, and Ru as active components in  methane steam reforming catalysts. Experiments utilizing methane with dimethyl sulfide as a feedstock for steam reforming revealed robust sulfur resistance in Pt and Ir catalysts. These catalysts completely regenerated from sulfur poisoning, achieving regeneration rates comparable to initial conversion rates. Noble metals can serve as alternatives to transition metal Nickel in reforming reactions, offering similar catalytic performance with higher sulfur resistance. However, the high cost of noble metals hampers their widespread application.