Propane dehydrogenation is a key industrial route to produce propylene without relying on oil. While current processes rely heavily on precious-metal catalysts such as Pt-based materials, developing efficient alternatives using earth-abundant metals has remained a challenge.
Recently, a study published in Nature Catalysis, Prof. XIAO Jianping's group from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaborations with Prof. XIAO Feng-Shou's group from Zhejiang University and Prof. LIU Xi from Ningxia University, has developed a high-performance cobaltosilicate zeolite catalyst (CoS-1). This catalyst has solely tetrahedral cobalt sites and none of the unstable cobalt species, achieving a propylene productivity as high as 9.7 kgC3= kgcat–1 h–1, surpassing that of industrial PtSn/Al2O3 catalyst.
The researchers employed density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations to study the stability of different active centers and uncover the mechanism behind the high performance of CoS-1 catalyst. They revealed that the flexible zeolite framework obviously lowers the dehydrogenation barriers at isolated cobalt sites due to entropic effects, resulting in a lower barrier than Pt3Sn alloy.
Microkinetic simulations further showed that while CoS-1 has a lower dehydrogenation barrier, its overall reaction rate at initial conversions is slightly lower than Pt3Sn, due to reduced propane concentration at isolated Co sites—an effect of entropy loss during diffusion into the zeolite channels.
Importantly, CoS-1 exhibits excellent long-time stability. The researchers proved that this can be attributed to the non-bonding adsorption of propylene within the zeolite, enabling rapid product desorption and reducing coke formation.