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Degradation as a synthetic pathway?

Zeolites are extensively studied materials with a high potential for real-life use and industrial applications. However, these applications are often limited by zeolite synthesis, which usually demands harsh conditions and is thus unsuitable for preparing chemically labile materials. Such materials have now been successfully prepared by the research group of Professor Jiří Čejka and Associate Prof. Maksym Opanasenko, in the Department of Physical and Macromolecular Chemistry, and the Charles University Centre of Advanced Materials (CUCAM). Their article has been published in the prestigious Journal of the American Chemical Society (JACS).

Zeolites are crystalline silicates with a microporous structure. They are constructed from silica (SiO2) building blocks, but they can contain other elements. These atoms then form acidic centers. “Zeolites are crucial industrial catalysts. They are used in oil refining (especially splitting longer chains into shorter ones), and many other petrochemical processes. They are also great adsorbents due to their microporous structure, which creates a large specific surface. You can also see them in laundry detergents, where they work as ion exchangers and thus lower the water hardness” explain scientists from the group of Synthesis, catalysis, and advanced materials who conducted this new study.

Structure of a new zeolite: transmission electron microscope image and a schema.


The problem remains in the targeted synthesis of zeolites. In some cases, they can be prepared using the assembly-disassembly-organization-reassembly (ADOR) method. The ADOR method is based on the synthesis of a suitable parent zeolite with germanium, which can be decomposed in water or acid. The new study focuses on catching the labile zeolites that arise during the post-synthetic processes in germanosilicate zeolites (where some atoms of silicon are replaced by germanium). “Using this method, we managed to catch the daughter zeolite phase, which was previously (at first glance) unsuccessfully subjected to the ADOR method”, according to the authors of the study.

The resulting zeolite was characterized using various methods to optimize the “capture”. In the beginning, the researchers were only able to capture the desired phase after approximately 5 minutes of hydrolysis; after 30 minutes, the degradation (in water) was already completed. But by adding aliphatic alcohol, the degradation process was slowed down, and the product was stabilized for up to 24 hours.

Their new method can be applied not only to this zeolite but also to any other chemically labile zeolite and may thus open up new pathways to study perspective materials.

The original study: https://doi.org/10.1021/jacs.3c00423

Published: Apr 24, 2023 02:40 PM

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