PolyU scientists uncover aluminium atom locations in Zeolites, ushering in a new era of sustainable catalysts

Zeolites, crystalline materials essential to the petrochemical industry, play a crucial role as catalysts in producing fine chemicals. Aluminium atoms within the zeolite framework create active sites that drive these catalytic reactions.

Researchers at The Hong Kong Polytechnic University (PolyU) have pinpointed the precise location of aluminium atoms in the zeolite structure. This breakthrough could enable the design of more efficient and durable catalysts. This advancement has the potential to:

• enhance petrochemical production,
• improve renewable energy storage,
• aid in air pollution control, expanding the applications of zeolites across various industries

The team's findings have been published in the journal Science. The research was led by :

• Shik Chi Edman Tsang (Chair Professor of Catalysis and Materials in the Department of Applied Biology and Chemical Technology at PolyU).
• Joined by Prof. Tsz Woon Benedict Lo, Associate Professor, and Dr. Guangchao Li, Research Assistant Professor and first author of the study

The team collaborated with researchers from the University of Oxford and the Innovation Academy for Precision Measurement Science and Technology at the Chinese Academy of Sciences. Zeolites are valued for their unique properties, including a well-defined microporous structure, high surface area, and adjustable acidity and basicity. They are essential for petrochemical refining, environmental catalysis, and fine chemical synthesis.

Prof. Edman Tsang said, "This discovery is a game-changer as it precisely identifies the location of aluminium atoms in the zeolite framework and how they are positioned, providing for the first time a structural elucidation of zeolite frameworks. This breakthrough allows scientists to design more efficient and targeted zeolite catalysts, making the chemical process faster, more energy-efficient and more environmentally friendly."

The placement of substitutional aluminium atoms within the zeolite framework influences molecular adsorption geometry, catalytic performance, and shape and size selectivity. Despite their significance, accurately pinpointing the location of these aluminium atoms and understanding their impact on catalytic behaviour has remained a longstanding challenge for researchers.

The research team investigated both lab-synthesised and commercial H-ZSM-5 zeolites, aiming to bridge the gap between fundamental science and practical applications by optimising H-ZSM-5 for advanced catalytic processes. They introduced an innovative approach that combines synchrotron resonant soft X-ray diffraction — a powerful technique for probing atomic structures — with probe-assisted solid-state nuclear magnetic resonance (SSNMR) and molecular adsorption methods. This integrated approach unveiled the interactions of molecules with aluminium active sites, leading to a breakthrough in precisely locating single and paired aluminium atoms within commercial H-ZSM-5 zeolites.

Prof. Benedict Lo stated, "We explored and combined various techniques to achieve a multidimensional view of the distribution of aluminium atoms and their interaction with adsorbed molecules, leading to insights into crucial reaction mechanisms. This provides scientists with a deeper understanding of the structure of zeolites."

The research findings pave the way for developing more efficient and selective catalysts with applications extending beyond petrochemicals to industries like renewable energy and pollution control. By reducing energy consumption, these innovations promote sustainability and minimise environmental impact. In petrochemical refining, the enhanced catalysts can boost fuel yield and quality — particularly for products like gasoline and olefins — while lowering energy usage.

In environmental catalysis, they help mitigate air pollution and contribute to cleaner air. Meanwhile, these advancements support hydrogen storage and utilisation for renewable energy and biofuels, playing a vital role in building a sustainable hydrogen economy.

Looking ahead, the team plans to collaborate closely with industry partners to translate their research into commercial applications. By leveraging the extensive networks and research expertise of the PolyU-Daya Bay Technology and Innovation Research Institute — which specialises in green chemistry and sustainable catalysis — they will work with domestic petrochemical companies to drive translational research and accelerate the commercialisation of advanced zeolite catalysts.

Their efforts are supported by PolyU's state-of-the-art facilities, including Hong Kong's only SSNMR facility and the upcoming Dynamic Nuclear Polarization SSNMR (DNP-SSNMR) spectrometer, the first of its kind in the Greater Bay Area and southern China. These resources will further enhance the team's research capabilities and accelerate their progress.

Dr Guangchao Li added, "We will develop further novel synthesis methods to precisely control the distribution and concentration of aluminium atoms, as well as their pore architectures in zeolites. This advancement will enable the design of catalysts with optimised activity, selectivity and stability for specific industrial applications."