SYNTHESIS OF ZEOLITE-BETA .1. USING TETRAETHYLAMMONIUM HYDROXIDE BROMIDE WITH ADDITION OF CHELATES AS TEMPLATING AGENTS

The synthesis of zeolite beta has been studied using the following tem plating agents: (i) tetraethylammonium hydroxide (TEA;) (ii) tetraethy lammonium bromide-diethanolamine; and (iii) tetraethylammonium hydroxi de-tetraethylammonium bromide-triethanolamine. TEA(+) ions and TEAOH m olecules only have a structure-directing effect. The ratio (Si + Al)/T EA(+) in the gel was varied from 2 to 10, the Si/Al ratio from 12 to 1 000. The temperature of crystallization was chosen in the range 368-44 3 K. The samples were characterized using X-ray diffraction, micrograp hs, chemical analysis, thermal analysis, IR spectroscopy and nitrogen adsorption. Zeolite beta of good crystallinity (micropore volume = 0.2 8 cm(3) g(-1)) was obtained with Si/Al ratios from 14 to 72. The acid strength and number of acid sites were determined from the calorimetri cally measured heat of NH3 sorption and from the TPD of NH3. The initi al acid strengths of zeolite beta (up to 185 kJ mol(-1)) are higher th an those of other high-silica zeolites. Polycrystalline agglomerates a re formed instead of small single crystals on the addition of diethano lamine to the synthesis gel. The agglomerates are characterized by a h igh intercrystalline volume (>0.47 cm(3) g(-1)), which can be influenc ed in a definite manner by variation of the TEABr/diethanolamine ratio . The presence of triethanolamine initiates the transformation of zeol ite beta into a SiO2 layer structure at 368 K.