CRYSTALLIZATION OF GALLIUM ANALOG OF ZEOLITE NU-23 FERRIERITE

The synthesis of pure Ga-substituted Nu-23 zeolite in the presence of cetyltrimethylammonium bromide (CTMA-Br) as templating agent has been carried out using the gel composition 2 (CTMA)2O:6.25 Na2O:M2O3:21.75 SiO2:800 H2O at 453 K. The phase purity and % crystallinity of the zeo lite product was estimated by XRD, sorption, i.r. and MAS n.m.r. measu rements. Thermoanalytical curves (d.t.a./t.g.) indicated that the temp lating species were occluded in the pores of the Ga-Nu-23 zeolite phas e and the same was decomposed around 973 K. The MAS n.m.r. spectra of the calcined sample indicated partial removal of Ga from the framework position. It is surprising to note that replacement of the source of Ga3+ by Al3+ in the above gel composition yields mordenite instead of Nu-23.