Probing Lewis acidity and reactivity of Sn- and Ti-beta zeolite using industrially important moieties: A periodic density functional study

摘要: Abstract The Lewis acidic nature and reactivity of two industrially important catalysts, viz., Sn Ti substituted beta zeolite (T-BEA) are analyzed using a unique combination structural parameters, energetics descriptors. To achieve this purpose, we adsorb the moieties (L) namely NH 3, H 2 O, CH 3 OH, CN on active sites T-BEA. calculations were performed periodic density functional method where valence electrons described plane wave basis set in conjunction with pseudo-potentials for core electrons. analysis properties these complexes reveals that TO 4 shows typical characteristic splitting 120°/90°, close to bipyramidal geometry as compared tetrahedral symmetry observed bare This is associated small variations framework bond lengths (≥0.08 A) substantially large variation angles (≤10°) all ligand-zeolite complexes. Further both cases zeolite, ligand interacts at optimum inter-atomic distance. Our interaction energies show adsorption stronger center than Ti. In general, order stability different T-BEA adducts  > H O > CH OH > CH CN. corresponding elongation reduction adsorbed molecules catalyst site, which can be taken measure red or blue shifted frequencies. Finally, global descriptors justify fact soft acid, Sn-BEA, strongly bases following Pearson's HSAB principle. However, hard Ti-BEA form stable adduct. Furthermore, HOMO–LUMO gap Sn-BEA–L lower Ti-BEA–L indicating its higher Ti-BEA.