Deactivation of an Fe-based catalyst in the dehydrogenation of light alkanes under H2S co-feeding: A case study

The effectiveness of a Ru-Fe/SiO₂ catalyst, which exhibits excellent propane dehydrogenation with H₂S co-feeding, was verified for the dehydrogenation of various lower alkanes. When the dehydrogenation characteristics of C2–C4 alkanes were evaluated under H₂S co-feeding, the Ru-Fe/SiO₂ catalyst exhibited a high dehydrogenation activity in all cases. However, a significant degradation tendency of the catalyst was observed when lighter alkanes with smaller carbon numbers were used as the feedstock. The deposition of coke (carbon) and solid sulfur and the reduction of Fe species were identified as the main factors responsible for catalyst degradation. To further evaluate the factors affecting catalyst degradation, the effect of co-feeding H₂ with the gas feedstock on the catalyst performance was investigated. The reaction stability improved significantly with the co-feeding of H₂ during ethane and propane dehydrogenation reactions. This outcome is attributed to the smooth reduction and removal of the carbon accumulated on the catalyst surface, which is the main cause of catalyst degradation.