SCM-25: A Zeolite with Ordered Meso-cavities Interconnected by12x12x10-Ring Channels Determined by 3D Electron Diffraction

Zeolites with large cavities that are accessible via widepore windows are desirable but very rare. They have been dominantlyused as catalysts in industry. Here we report a novel porousgermanosilicate SCM-25, the zeolite structure containing orderedmeso-cavities (29.9x7.6x6.0 A3) interconnected by 10- and 12-ringchannels. SCM-25 was synthesized as nanosized crystals by using asimple organic structure-directing agent (OSDA). Three-dimensional(3D) electron diffraction shows that SCM-25 crystallizes in theorthorhombic space groupCmmmwitha= 14.62 A,b= 51.82 A,c=13.11 A, which is one of the zeolites with the largest unit celldimensions. We demonstrate that 3D electron diffraction is a powerfultechnique for determining the complex structure of SCM-25,including the disorders and distributions of framework atoms silicon and germanium. SCM-25 has a high surface area (510 m2/g) and high thermal stability (700 degrees C). Furthermore, we propose a potential postsynthetic strategy for the preparation of zeoliteswith ordered meso-cavities by applying the ADOR (assembly-disassembly-organization-reassembly) approach.

Automated summary

A novel porous germanosilicate SCM-25 with large accessible cavities via widepore windows has been synthesized. It has a high surface area and thermal stability. The study also proposes a potential postsynthetic strategy for the preparation of zeolites with ordered meso-cavities.