Boosting propane dehydrogenation performance over the highly dispersed Co(Ⅱ) sites on ultra-high silica ZSM-5 zeolite

Propane dehydrogenation (PDH) has emerged as an effective way to address the problem of propylene production gap in recent years. However, industrial catalysts are challenged by the scarcity of Pt and toxicity of CrOx. Herein, a series of Co-based catalysts supported on MFI type zeolites with various Si/Al ratios were synthesized by regulating the acid sites to alleviate side reactions. The catalyst Co/ZSM-5-1500 exhibits the superior PDH performance due to the highest proportion of Co(Ⅱ) active sites. The initial C3H6 formation rate is 6.5 mmol g−1cat h−1, along with good long-term stability across three cycles. The Brønsted acid sites over ZSM-5-40 are prone to catalyzing side reactions of cracking and coke deposition to decrease propylene selectivity and stability. This work demonstrates that Co species supported on high silica ZSM-5 zeolite via impregnation method is favorable to generate the highly dispersed Co(Ⅱ) species on the surface of zeolites, and the Co(Ⅱ) species are responsible for excellent PDH performance.