Ambient pressure synthesis of hierarchical structured SAPO-5 molecular sieve with special morphology

Abstract

Hierarchical structured SAPO-5 molecular sieve was ionothermally synthesized by microwave irradiation using a mixture solution of succinic acid, choline chloride and tetraethyl ammonium bromide as solvent and template under ambient pressure. The effects of the molar ratios of P2O5/Al2O3 and HF/Al2O3, silicon source, and crystallization time on the structure of SAPO-5 molecular sieve were systematically investigated. The resulting SAPO-5 molecular sieve was characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), N2 physical adsorption-desorption and 29Si magic-angle spinning nuclear magnetic resonance (29Si MAS-NMR) techniques, respectively. The results indicate that intra-crystalline and inter-crystalline mesopores coexist within the SAPO-5 molecular crystals, while 29Si MAS-NMR test shows that the incorporation of Si in the sample follows the SM3 mechanism. In addition, SEM images exhibit that hierarchical structured SAPO-5 molecular sieve with hexagonal nanometer-disc morphology can be synthesized under specific synthetic conditions.