ZEOLITE SYNTHESIS IN THE PRESENCE OF AZONIA-SPIRO COMPOUNDS AS STRUCTURE-DIRECTING AGENTS

Hydrothermal syntheses of zeolites were carried out in the presence of 5-azonia-spiro-[4,5]-decane (I), 6-azonia-spiro-[5,5]-undecane (II) a nd 6-azonia-spiro-[5,6]-dodecane (III) as structure-directing agents ( SDA). The low selectivity of the azonia-spiro compounds I-III was demo nstrated by the variety of zeolite structures obtained, including MOR, MTW, beta, EUO, EU-4 and the new ERS-10 phase. Pure MOR and MTW were obtained with all three SDAs, and their formation was found to be dire ctly correlated with the SiO2/Al2O3 molar ratio in the reactant mixtur e. This conclusion was supported by the determination of the location and energetics of I-III in the two porous structures. Molecular mechan ics and dynamics calculations showed favorable and comparable non-bond ing interactions of the three azonia-spiro compounds with the MOR and MTW frameworks. Molecular dynamics calculations showed that the azonia -spiro compound I experiences higher steric constraints when docked in MTW than in MOR. These results account for the larger signal linewidt hs observed in the C-13 MAS NMR spectra of the MTW precursor with resp ect to the MOR one. Pure ERS-10 phase was obtained using II as structu re-directing agent, starting from a reactant mixture containing tetrae thylorthosilicate and aluminum-tri-isopropoxide as source of silica an d aluminum, respectively, and with a SiO2/Al2O3 molar ratio of 100. Pr eliminary structural characterization indicates that the framework top ology of ERS-10 is closely related to those of EUO and to the recently reported CIT-5 zeolites. (C) 1998 Elsevier Science B.V. All rights re served.