Mechanism of template removal for the synthesis of molecular sieves using dielectric barrier discharge
•Dielectric barrier discharge plasma can remove the template at low temperature.•The rapid plasma template removal is conducted at atmospheric pressure.•The plasma template removal follows radical generation and oxidation mechanism.•The plasma template removal is a chemical green process.
Molecular sieves are extensively employed in catalysis, separation and many other fields. Various organic templates are commonly applied for the synthesis of molecular sieves. However, thermal treatment has to be conducted at elevated temperature to remove the template after synthesis. The high temperature operation may destroy the structure of molecular sieves. A dielectric-barrier discharge (DBD) plasma technique, initiated at ambient conditions, was recently developed for the quick, safe and easy removal of templates from molecular sieves. In this work, the mechanism of DBD plasma template removal is investigated. The study confirms that dissociation of template molecule by active species (like electrons and excited oxygen species) and oxidation of radicals (from the dissociation) by active oxygen species (like ozone and excited oxygen species) are the mechanism of the DBD plasma enhanced template removal. The thermal image confirms that the DBD plasma template removal is conducted under temperature around 125 °C. The thermal effect can be ignored. The present study is leading to a unique way for the syntheses of various micro- and meso-porous materials.
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Journal: Catalysis Today - Volume 256, Part 1, 1 November 2015, Pages 137–141