Insights into the active Fe species of Fe/ZSM-5 catalysts for ethane dehydrogenation

Catalytic ethane dehydrogenation to ethylene is an attractive route for ethylene production following the shale gas revolution. However, its industrial implementation remains challenging due to high costs and environmental concerns. Iron-based catalysts have been identified as promising alternatives, while their catalytic performance is significantly dependent on the coordination environment and oxidation state of the iron species. Herein, a series of Fe/ZSM-5 catalysts were synthesized via urea precipitation (FeZ-P) and incipient wetness impregnation (FeZ-I) methods to investigate the relationship between Fe species evolution and catalytic behavior during ethane dehydrogenation. The FeZ-P catalysts exhibited significantly enhanced activity compared with FeZ-I, which was attributed to the improved dispersion of iron species and their favorable transformation behavior under reaction conditions. Detailed characterizations of fresh and spent catalysts revealed that the initial Fe 2 O 3 species on FeZ-P surface possessed limited dehydrogenation activity but underwent reaction-induced reduction and carbonization, generating Fe 3 C with enhanced ethane dehydrogenation performance. In contrast, the Fe 2 O 3 bulks on FeZ-I exhibited slower transformation rates, resulting in inferior catalytic activity. Air oxidation treatment enabled partial regeneration of the catalyst by removing carbon deposits and modifying Fe species evolution. This study highlights the importance of regulating Fe species dispersion and dynamic reduction-carbonization behavior, through which catalytically active Fe 3 C can be generated for enhanced ethane dehydrogenation performance. These findings provide valuable insights into the rational design of efficient Fe-based catalysts for non-oxidative alkane dehydrogenation.