Structure-direction towards the new large pore zeolite NUD-3.

Area of Science:

• Materials Science
• Chemistry
• Crystallography

Background:

• Zeolites are crystalline aluminosilicates with diverse industrial applications.
• Topologically similar zeolites can exhibit distinct framework structures and properties.
• Understanding structure-property relationships is crucial for designing novel zeolites.

Purpose of the Study:

• To characterize the novel zeolite NUD-3.
• To compare the framework structure of NUD-3 with topologically identical zeolites ITQ-21 and PKU-14.
• To elucidate the mechanism of structure-directing agent (SDA) action in forming the NUD-3 framework.

Main Methods:

• X-ray diffraction for structural determination.
• Synthesis of NUD-3 using a specific dication SDA.
• Molecular simulations to investigate SDA-framework interactions.
• Comparison of zeolite framework topologies.

Main Results:

• NUD-3 possesses a large-pore, three-dimensional channel system topologically identical to ITQ-21 and PKU-14.
• A key difference lies in the ordering of a 4-membered ring within the zeolite framework: absent in PKU-14, disordered in ITQ-21, and fully ordered in NUD-3.
• Molecular simulations identified the mechanism by which the dication SDA, 1,1'-(1,2-phenylenebis(methylene))bis(3-methylimidazolium), directs the ordering of this critical 4-membered ring.

Conclusions:

• NUD-3 represents a new zeolite structure with a unique, ordered framework.
• The specific dication SDA plays a crucial role in templating the ordered arrangement of the 4-membered ring.
• This work provides insights into zeolite synthesis and the design of novel materials with tailored properties.