Coupling Different Periodic Building Units for Intergrowth Zeolites

Area of Science:

• Materials Science
• Catalysis
• Crystallography

Background:

• Intergrowth zeolites are vital industrial catalysts, yet their synthesis and phase competition are poorly understood due to limited knowledge of zeolite crystallization mechanisms.
• Current understanding of zeolite formation primarily focuses on single-phase structures, leaving a knowledge gap in the rational synthesis of complex, multi-phase disordered zeolites.

Purpose of the Study:

• To theoretically demonstrate the non-defective connection of sodalite and cancrinite cage layers (PerBUs) for intergrowth zeolite formation.
• To experimentally synthesize a novel family of intergrowth zeolites with controllable phase composition.
• To provide evidence for a layer-by-layer crystal growth mechanism in zeolite formation.

Main Methods:

• Theoretical modeling to predict the connection of sodalite (FAU/EMT) and cancrinite (SBT/SBS) cage layers.
• Synthesis of intergrowth zeolites using a multiple inorganic cation approach with an unselective organic structure-directing agent.
• Characterization of the synthesized FAU/SBT/SBS intergrowths (PST-34 family) to confirm phase composition and structure.

Main Results:

• Demonstrated that sodalite and cancrinite cage layers can connect nondefectively via inverted and mirrored double rings.
• Successfully synthesized an unprecedented family of FAU/SBT/SBS intergrowth zeolites (PST-34) with tunable FAU content.
• Provided experimental validation for the proposed layer-by-layer crystal growth mechanism.

Conclusions:

• The study elucidates a mechanism for non-defective intergrowth of different periodic building units (PerBUs) in zeolites.
• A novel synthetic strategy enabling controlled fabrication of intergrowth zeolites has been established.
• Understanding the cooperative interactions between structure-directing agents is key to designing complex, multi-phase zeolite materials.