Redefining the Role of Cobalt Oxide in Ethane Dehydroaromatization: Insights into Enhanced Catalytic Activity and Stability

Abstract

Cobalt is recognized as an active catalyst in ethane dehydroaromatization (EDA) reactions due to its efficient ethane cracking capability. In order to optimize cobalt's strong ethane cracking capability, it was loaded onto HZSM-5 zeolite through impregnation. This study was conducted with Co-loaded HZSM-5 catalysts with an incipient wetness impregnation method and witnessed an increase of catalytic activity with a long induction period. We elucidated the prior reduction of external Co₃O₄ before BTX synthesis and the novel roles of external Co₃O₄ in suppressing deactivation─an aspect not extensively explored in previous studies utilizing single Co catalysts. The utilization of Co₃O₄ as a catalyst on external zeolites promotes the generation of carbon nanotubes (CNTs) while inhibiting the formation of graphite, thereby suppressing the deactivation of the catalyst. Furthermore, experimental comparisons with Co catalysts synthesized via ion exchange and physical mixing underscore the role of Co ions anchored to internal zeolite as active sites for BTX synthesis as well as emphasize the importance of external Co₃O₄ in enhancing catalyst stability.

Keywords: Co/HZSM-5; carbon nanotubes; catalytic stability; cobalt oxide; ethane dehydroaromatization.