SYNTHESIS AND CHARACTERIZATION OF ZINCOSILICATES WITH THE SOD TOPOLOGY

The incorporation of Zn2+ into tetrahedral framework positions of zeol ites with the sodalite topology (SOD) is obtained by direct synthesis. The zincosilicates are characterized by thermal analyses, a Rietveld refinement of powder X-ray diffraction (XRD) data, and infrared (IR) a nd H-1, Na-23, C-13, and Si-29 MAS NMR spectroscopies. A zinc substitu tion level as high as Si/Zn = 6-7 is achieved and constitutes by far t he largest extent of isomorphous substitution by a doubly charged hete roatom in the framework of a zeolite. Two types of beta-cage occupanci es (TMA+ and Na+) are observed.