Open Framework Structure of the New Pure-Germania Zeolite ITQ-35 Solved by 3D Electron Diffraction

Area of Science:

• Materials Science
• Inorganic Chemistry
• Crystallography

Background:

• Open-framework germanate materials are crucial in catalysis and gas separation.
• Developing new germanate structures with tunable properties remains a significant challenge.
• Organic structure directing agents (OSDAs) play a key role in templating novel framework architectures.

Purpose of the Study:

• To synthesize and characterize a novel pure open-framework germanate material.
• To elucidate the unique pore structure and framework density of the new material.
• To explore the potential of photochemically synthesized OSDAs in germanate synthesis.

Main Methods:

• Synthesis of a novel organic structure directing agent (OSDA) via photochemical [2+2] cycloaddition.
• Structure determination using a combination of precession electron diffraction tomography (PEDT) and powder X-ray diffraction (PXRD).
• Framework density calculation and comparison with existing zeolitic materials.

Main Results:

• Successful synthesis of a pure open-framework germanate, designated ITQ-35.
• ITQ-35 exhibits a tridirectional pore system with 8-ring pores interconnected by 12-ring channels.
• The material possesses one of the lowest framework densities (12.7 T/1000 ų) reported for pure germanate zeolitic materials, comparable to aluminogermanates like PKU-9.

Conclusions:

• The study presents a new germanate material, ITQ-35, with a unique structure and low framework density.
• Photochemically synthesized OSDAs are effective in directing the formation of novel germanate frameworks.
• ITQ-35's structural characteristics suggest potential applications in areas requiring materials with high porosity and low density.