Local geometry of AlO4~-and SiO4 tetrahedra in the silicone rich chabazite.A combined high resolution NMR and QM/MM study

摘要

Local geometry of AlO4 and SiO4 tetrahedra in silicon rich(Si/Al 38)chabazite was investigated using ~(27)Al 3Q and ~(29)Si MAS NMR spectroscopy and QM-Pot calculations.We further studied the effects of(1)Al as nearest neighbor and(2)silanol "nest"on the SiO4 local geometry as well as ~(29)Si NMR chemical shift.Silanol "nests"are a model of a defect(vacant T site after a dealumination)in a zeolite framework.