Abstract: A large single crystal of TPAF-AlPO₄-5 molecular sieve was synthesized by hydrothermal crystallization in the presence of ammonium fluoride.Starting material composition was · 1 P₂O₅ · 1 Al₂O₃ · 2.2 TPAOH · 1.7 NH₄F ·318 H₂O.The crystal size has a hexagonal prism with 80μm across and 500μm length.The structure of tetrapropylarnmonium fluoride-aluminium phosphate type-5 was investigated with X-ray diffraction.The unit cell composition is 12AlPO₄ · TPAF, space group P6cc (a=13.740(5), c=8.474(4)Å).Average bond distances are: P-O 1.564Å and Al-O 1.640Å ,which may be due to the partial disorder of the arrangement of P, Al in the framework.The angles of O-T-O and T-O-T (T=P, Al) are 102-116° and 148-176°, respectively.Residue electron density was not well enough defined to give a precise position for tetrapropylammonium fluoride (TPAF).The template agent, TPA⁺ cations, situate in the 12-ring channels and F^-anions locate in double 4-rings near the 12-ring channels.

Key words: AlPO₄-5, molecular sieve, single crystal