• The research work has been carried out through a collaboration between the Instituto de Nanociencia y Materiales de Aragón, INMA (CSIC-UNIZAR), ShanghaiTech University (China), the Max-Planck Institute and Jilin University (China).
Zeolites are inorganic compounds, mainly composed of silicon, aluminium and oxygen, with a porous structure formed by channels and/or cavities that present high thermal stability. They are widely used in the chemical and pharmaceutical industry and are the most important heterogeneous catalyst in the world. Zeolites are capable of transforming raw materials into products with high added value while reducing production costs, making them indispensable in the production of petrol, plastics (PET or styrene, among others), nylon or even for the treatment of gases from vehicles.
A unique and inherent characteristic of zeolites is their confinement capacity, being able to accommodate different types of compounds within their structure. Thanks to this capacity, in addition to their multiple industrial applications, they are capable of generating advanced materials that respond to society’s new challenges in areas related to the environment, reducing the carbon footprint, the use of alternative energy sources, water treatment and recycling.
All these applications are directly related to the structure of zeolites; among the many challenges that remain to be answered in the field of catalysis in general and zeolites in particular is the local characterisation of both oxygen bonds and additional atoms incorporated into the lattice. These aspects are fundamental to understanding the catalytic capabilities of zeolites that would facilitate the design of materials with improved functionalities.
The research team led by Álvaro Mayoral, a researcher at the Instituto de Nanociencia y Materiales de Aragón, INMA (CSIC-UNIZAR), together with Prof. Terasaki from ShanghaiTech University (China), have managed to locate and identify all the atoms in two of the most industrially important zeolites, including oxygens, cations outside the lattice itself and atoms that replace silicon and become part of the zeolitic structure. The results of the research have been published on the cover of the prestigious journal Angewandte Chemie.
To carry out this research work, the team, which includes Álvaro Mayoral, has made use of advanced transmission electron microscopy techniques. In addition, thanks to the use of image analysis, electron diffraction and theoretical calculations, they have managed to study the structures of two of the most important zeolites in the industry (Na-LTA and Fe-MFI) and to observe for the first time the presence of transition metals (iron) incorporated into the lattice, which are incorporated randomly, replacing silicon. Thanks to the study, oxygen bridges have also been observed in both structures, which represents the first step towards the localisation of acid centres, responsible for acid catalysis reactions (used, for example, in the production of nylon). The results presented in this work provide essential clues to control and design the chemically active centres at the atomic level that are essential for the generation of new functional materials with advanced properties.
