Aluminosilicate Zeolite EMM-28 Containing Supercavities Determined by Continuous Rotation Electron Diffraction.

Area of Science:

• Materials Science
• Crystallography
• Nanotechnology

Background:

• Zeolites are crucial microporous materials with diverse industrial applications.
• Developing new zeolites with unique structures and properties is an ongoing research area.
• Structure determination of novel materials can be challenging with conventional techniques.

Purpose of the Study:

• To synthesize and characterize a new aluminosilicate zeolite, EMM-28, on a large scale.
• To determine the crystal structure of EMM-28 using advanced diffraction techniques.
• To explore the potential of continuous rotation electron diffraction (cRED) for structure solution.

Main Methods:

• Large-scale synthesis of EMM-28 using 1,1-(3,3-(1,3-phenylene)bis(propane-3,1-diyl))bis(1-methylpyrrolidinium) hydroxide as an organic structure directing agent (OSDA).
• Powder X-ray diffraction (PXRD) for initial characterization.
• Continuous rotation electron diffraction (cRED) for crystal structure determination.
• High-resolution transmission electron microscopy (HRTEM) for structural confirmation.

Main Results:

• Successful large-scale synthesis of EMM-28 with a yield of 77%.
• EMM-28 exhibits a unique framework structure with large supercavities (>21 Å) connected by 1D 10-ring channels.
• The crystal structure was solved and refined using cRED data, demonstrating its efficacy for materials with limited PXRD data.
• HRTEM confirmed the proposed structure model.

Conclusions:

• EMM-28 represents a new zeolite material with a unique pore architecture.
• Continuous rotation electron diffraction (cRED) is a powerful tool for determining the structures of novel crystalline materials, especially when PXRD data is limited.
• The findings contribute to the library of zeolite structures and may open avenues for new catalytic or separation applications.