Quantum modelling studies of local coordination of T-atoms in zeolites

Aluminosilicate zeolites are solid acids that may act as catalysts for various reactions, such as the conversion of methanol to light alkenes. Recent NMR results obtained in a joint project between UiO and the group of Prof. Francis Taulelle in Versailles , France, give new insight into the local environment at the active sites in zeolites. A longstanding issue in this area of research is whether aluminium is randomly distributed among the different framework sites, if certain positions are preferentially occupied, or if ordering may occur. Advanced solid-state NMR results indicate that framework T-atoms may show considerable mobility during calcination and also during the catalytic reaction. Further, aluminium atom pairing appears to take place to a large extent. The postdoc for whom we apply for funding will perform quantum chemical calculations to elucidate the relative stabilities of various T-atom configurations and crystal defects. Further, he or she will attempt to determine the mechanism(s) of T-at om diffusion in the material. Finally, NMR spectra will be computed and compared to experimental results to yield far more reliable characterization than what would be available from experiment or theory alone.