Exploring the reactivity of framework vanadium, niobium, and tantalum sites in zeolitic materials using DFT reactivity descriptors

The acid-base properties of zeolites with group 5 transition metal framework sites are investigated, and a first step into the understanding of their acid/base and redox properties is undertaken using DFT reactivity descriptors. It is evidenced, using sodalite as model system, that zeolites with vanadium framework sites are more nucleophilic than zeolites with niobium and tantalum framework sites. It is predicted that the formation of carbonates would be favorable in zeolites with Ta framework sites compared with V framework sites, whereas the basicity of the bridging oxygens is predicted to interact preferentially with a soft nucleophile. In this context, the poisoning of the deNO(x) catalysts in the presence of SO2 is discussed.