SYNTHESIS OF ZEOLITE ZSM-48 IN THE PRESENCE OF 1,8-DIAMINOOCTANE AND HEXAMETHONIUM BROMIDE - ANALYSIS AND C-13-NMR SPECTROSCOPY

Several organic compounds favour the formation of the high-silica zeolite ZSM-48. This paper gives insight into the state of the organic molecules (1,8-diaminooctane-C8DNA and hexamethonium bromide - HMBr2) occluded in the channels of ZSM-48. Combined thermal analysis and C-13-NMR techniques have been used to characterize their structural state in the pore volume of the as-synthesized zeolite and their thermal stability. A decomposition scheme is proposed in each case. Both C8DN and HMBr2 are incorporated intact into the intracrystalline volume of ZSM-48 and they ensure a good pore filling of the zeolite lattice. By contrast, for the (HM)ZSM-48 synthesized in the presence of HM++ and ammonium ions, a partial decomposition of hexamethonium ions to hexyltrimethylammonium and trimethylammonium ions has been observed, the latter compounds also being occluded in ZSM-48. The progressive removal of the various organics occluded in ZSM-48 could be followed by TG-DTA and a decomposition scheme is proposed in each case.