A novel “zeolite blending” method has successfully produced CON-type zeolites with unprecedentedly high aluminum content, report researchers from the Institute of Science Tokyo. By combining multiple zeolite precursors to guide the synthesis process, this innovative strategy overcomes long-standing limitations in controlling aluminum content in zeolite frameworks. The proposed approach will open new possibilities for catalyst development across various industrial applications, including petrochemical processing, fine chemicals production, and environmental remediation.

Zeolites, crystalline porous materials with ordered channels and cavities, serve as efficient catalysts in many industrial processes due to their unique structural properties. These versatile materials are known for their ability to selectively facilitate chemical reactions at their acidic sites, which are created when aluminum (Al) atoms are incorporated into their silica framework. Thus, the Al content directly influences a zeolite’s acidity and catalytic behavior, making precise control over this parameter crucial for optimizing their performance.

However, despite decades of research and various synthesis methods, scientists still struggle to precisely control the Al content in certain zeolite structures. This is particularly true for CON-type zeolites, where achieving a silicon-to-aluminum (Si/Al) ratio below 100 through direct synthesis has remained a significant challenge.

Fortunately, in a recent study published in Angewandte Chemie International Edition, a research team led by Professor Toshiyuki Yokoi from the Institute of Science Tokyo, Japan, developed an innovative approach that overcomes this long-standing limitation. The team pioneered a novel synthesis method, called “zeolite blending,” that uses multiple types of zeolites as starting materials to directly crystallize zeolites with previously unattainable compositions.

The research team employed an interzeolite conversion/transformation method, focusing on the common composite building units (CBUs) shared between precursor zeolites and the target structure. Initially using single zeolite precursors, they successfully synthesized CON-type zeolites with a Si/Al ratio of approximately 40—already an improvement over conventional methods. However, the real breakthrough came when they combined multiple zeolite types as starting materials.

The researchers discovered that Beta zeolite served as an effective base material while adding small amounts of MFI-type zeolite significantly enhanced the formation of high-aluminum CON-type structures. Simply put, this blending approach strategically combined the necessary building blocks—the CBUs—from different zeolite frameworks, creating an optimal environment for the crystallization of the target structure with the desired Al content.

“This strategy enabled us to obtain CON-type zeolites with a Si/Al ratio of approximately 20, which could not be achieved with a single zeolite precursor. It represents the first instance of the direct synthesis of zeolites with such a high Al content on a global scale,” says Yokoi.

The resulting high-Al CON-type zeolites demonstrated superior properties compared to those produced through conventional post-treatment methods, including smaller particle sizes and improved Al distribution. These characteristics make them particularly promising for applications in catalysis, especially for the methanol-to-olefin reaction—a critical process in the production of valuable petrochemicals from alternative feedstocks.

Beyond this immediate success with CON-type zeolites, the proposed zeolite blending method opens new possibilities for synthesizing various zeolite structures with previously unattainable compositions. “Further analysis of this blending method, like the physicochemical properties of the starting materials and their role, is currently in progress,” notes Yokoi.

Overall, this newfound approach could lead to a paradigm shift in zeolite synthesis methodologies, potentially enabling the development of new catalysts with enhanced performance for industrial applications. By expanding the compositional range of zeolites, this research not only advances our fundamental understanding of zeolite crystallization but also paves the way for more efficient and sustainable catalytic processes.