Active sites in zeolite catalysts. DFT and multi-spectroscopic analysis

Transition metal exchanged forms of zeolites were discovered as exceptional redox catalysts. The properties and structure of catalytically active transition metal species depend on the structure of the zeolite framework, Al concentration (Si/Al ratio), and Al distribution. We will determine the Al distribution in the zeolites mordenite and SSZ-13 and use this knowledge for mordenite together with the already known Al distribution in the zeolite ZSM–5 to develop plausible models of the catalytically active transition metal species accommodated in the active sites. Periodic DFT methods using experimental data as input and, furthermore, FTIR spectroscopy, Raman spectroscopy, 27Al 3Q, 29Si, 7Li, and 23Na 3Q MAS NMR spectroscopy, and UV–vis spectroscopy will be the tools to proceed in our research. Experimental results will also serve to test predictions obtained from calculations. Keywords in English zeolite; DFT; periodic DFT; ZSM-5; mordenite; SSZ-13; MFI; CHA; Al distribution; Al siting; transition metal exchanged zeolite