How pore interconnectivity between components boosts diffusion and catalytic efficiency in industrial zeolite-based catalysts

In practice, industrial catalysts typically consist of both "zeolitic components" and "non-zeolitic components," which together play important roles in processes like polyolefin catalytic cracking and residue fluid catalytic cracking. Most research to date has focused mainly on the diffusion behaviors of a single zeolitic component or non-zeolitic component, neglecting the interfacial interactions between them.

In a study published in Journal of the American Chemical Society, a research team led by Prof. XU Shutao, Prof. WEI Yingxu, and Prof. LIU Zhongmin from the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences, collaborating with Prof. YAN Zifeng's team from China University of Petroleum (East China), investigated the diffusion and cracking kinetics of zeolite-based multicomponent model catalysts.

Zeolites such as ZSM-5 are essential components in industrial catalysis with widespread applications in petroleum refining, coal conversion, and environmental remediation. Researchers designed a series of model cracking catalysts composed of ZSM-5 and mesoporous SiO₂ with precisely controlled interfacial channel connectivity. These catalysts enabled systematic exploration of structure-diffusion-reaction relationships at zeolite and non-zeolite interfaces. 

Researchers quantitatively analyzed both global and zeolitic diffusion behaviors in these multicomponent systems by employing advanced characterization techniques including hyperpolarized (HP) ¹²⁹Xe nuclear magnetic resonance (NMR), intelligent gravimetric analysis (IGA), and time-resolved in situ Fourier-transform infrared (FTIR) spectroscopy.

They revealed a pronounced "funnel effect" from the mesopores in non-zeolitic component, which showed that a well-connected micro-/mesopore network can effectively accelerate interfacial diffusion and fully enhance the catalytic efficiency of the zeolitic component. This finding highlighted the foundational functions of pore interconnectivity in facilitating the free migration of reactant species between zeolitic and non-zeolitic components.

"Our study shows that for the elaborate design of industrial multicomponent catalysts, more attention should be paid to constructing highly interconnected hierarchical pore structures both within and between zeolitic and non-zeolitic components as well as tuning their surface properties," said Prof. XU.