Ambient Pressure Synthesis of Hierarchical Structured SAPO-5 Molecular Sieve with Special Morphology

doi:10.15541/jim20130595

Abstract

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/Al₂O₃and 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.

Key words: SAPO-5, eutectic mixture, microwave radiation, hierarchical structured

CLC Number:

O613

ZHAO Xin-Hong, LI Xiao-Bin, CHEN Jing, QI Yong-Dong, WEN Juan-Juan, JI Dong. Ambient Pressure Synthesis of Hierarchical Structured SAPO-5 Molecular Sieve with Special Morphology[J]. Journal of Inorganic Materials, 2014, 29(8): 821-826.

Figures/Tables 7

Fig.1 XRD patterns of products synthesized with different molar ratios of P2O5/Al2O3 to HF/Al2O3

Fig. 2 XRD patterns of products synthesized with different silicates (T-(C2H5O)4Si, S-Na2SiO3·9H2O)

Fig. 3 XRD patterns of products synthesized with different HF additions and crystalization time

Table1 N2 physical adsorption-desorption characterization data of representative samples

Sample	BET surface area/(m²?g^-1)	Micro surface area/(m²?g^-1)	Exter surface area/(m²?g^-1)	Micropore volume/(cm³?g^-1)	Mesorpore volume/(cm³?g^-1)
Si_0.2AlP_1.1F_0.0-1.0	245	147	98	0.067	0.207
Si_0.2AlP_1.1F_0.5-1.0	120	28	92	0.012	0.285
Si_0.2AlP_1.1F_1.0-1.0	279	235	44	0.108	0.100
Si_0.2AlP_1.1F_1.0-2.0-S	155	79	76	0.036	0.275
Si_0.4AlP_1.1F_2.0-2.0	320	265	55	0.122	0.203
Si_0.8AlP_1.1F_1.0-2.0	305	235	70	0.108	0.229

Fig. 4 N2 physical adsorption-desorption isotherm with pore size distribution of hierarchical structured SAPO-5 molecular sieves

Fig. 5 SEM and TEM images of three kinds of hierarchical structured SAPO-5 molecular sieves (a, a’)Si0.2AlP1.1F0.0-1.0; (b, b’) Si0.4AlP1.1F2.0-2.0; (c, c’) Si0.8AlP1.1F1.0-2.0

Fig. 6 29Si MAS NMR spectra of Si0.2AlP1.1F0.0-1.0 (a) and Si0.8AlP1.1F1.0-2.0 (b)

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