SYNTHESIS OF SAPO-N POLYCRYSTALLINE FILMS

Synthesis of SAPO-n polycrystalline films were studied to get a better understanding of crystal growth process of SAPO-n (Table 1). It was found that SAPO-5, -11, -17, -34 and -41 polycrystalline films were obtained on the Teflon slabs. About 10 approximately 20% of the starting hydrogels was converted to the films. The large differences in the surface morphology and the surface Si concentration were observed between the Teflon and the solution sides of the films obtained. The Teflon side of the films was formed of an aggregate of crystals with small crystal size as compared with the solution side (Fig. 1). The Si/Al ratio of the solution side was larger than that of the Teflon side (Table 2). From these results, it was concluded that during the initial crystallization of SAPO-n the SAPO-n crystals with the lower Si concentration, AIPO-n, are preferentially crystallized on the Teflon slab.