Current project:

Title: Beyond tetrahedral coordination in zeolite-type materials - A computational approach

3-year project (05/2018 to 05/2021), funded by the German Research Foundation (DFG)

Project description

Zeolites are a class of crystalline inorganic materials consisting of a three-dimensional framework of corner-sharing tetrahedra. By virtue of their intrinsic porosity, zeolites and related materials with zeolite-type topologies (zeotypes) find use in various large-scale applications, e.g. in gas and liquid separation, catalysis, and ion exchange. Ideal zeolites correspond to a perfect framework of tetrahedrally coordinated atoms (T atoms) linked by oxygen atoms. However, there are many examples of actual zeolite structures where some T atoms have a coordination number (CN) that is larger than 4 because additional non-bridging species are bonded to these sites. The present project explores such zeolite-type materials with 'higher-coordinated' T atoms by means of electronic structure calculations in the framework of dispersion-corrected density-functional theory (DFT). The focus will be on two groups of materials, namely (1) fluoride-containing all-silica zeolites and (2) hydrated aluminophosphates (AlPOs). It is the primary aim of the project to further the understanding of zeolite-type systems with higher-coordinated T atoms on a fundamental level. Nevertheless, it can be anticipated that the findings will also have a certain relevance to applications. For example, new insights into the structure-directing properties of fluoride anions may aid the rational development of new synthesis routes, and a better atomic-level understanding of the framework-water interaction in hydrated AlPOs can help to explain the different degree of water stability of these materials, which is a crucial property for various applications.