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A series of hierarchical SAPO-34 zeolites with controllable crystallite sizes ranging from 40 to 200 nm and morphologies from well-dispered urtral-small nanocrystals to compact spherical-like polycrystallite aggregates were fabricated by only modulating the Si/TEAOH molar ratios in the gel mixture. [Display omitted] • Hierarchical SAPO-34 zeolites are synthesized without a secondary template. • A possible forming mechanism of SAPO-34 zeolite is proposed. • Crystal sizes and morphologies can be well modulated by controlling Si/TEAOH molar ratios. • The rich mesopore structure resulted from the intercrystal pores of nanoparticles is fabricated. A series of hierarchically porous SAPO-34 zeolites with tunable crystal sizes varying from 40 to 200 nm were synthesized with different morphologies from well-dispersed ultra-small nanocrystals to compact spherical-like polycrystalline aggregates by only changing the Si/TEAOH (TEAOH: tetraethylammonium hydroxide) molar ratios in the gel precursors without using any meso -templates. The hierarchical samples were systematically characterized by XRD, FT-IR, SEM, TEM, XRF, 29Si MAS NMR spectra and N 2 adsorption–desorption. It reveals that hierarchical SAPO-34 nanocrystals with high crystallinities, larger external surface areas (61 – 125 m2/g) and mesopore volumes (0.15 – 0.29 cm3/g) were obtained under current synthesis condition. [ABSTRACT FROM AUTHOR]

Flowerlike hierarchical SAPO-5 molecular sieve with affluent mesopores derived from loosely aggregating of primary nano-rods-like crystals is prepared via a hydrothermally rota-crystallization route using tetrapropylammonium hydroxide as a single structure-directing agent. • Flowerlike SAPO-5 molecular sieve is synthesized by a hydrothermally rota-crystallization route. • Flowerlike SAPO-5 is composed of loosely aggregating rod-like crystals with a size of ~20 nm. • Mesopore of 2–8 nm resulted from the intercrystalline spaces is fabricated. Flowerlike hierarchical SAPO-5 molecular sieve was fabricated by a hydrothermally dynamic crystallization route using tetrapropyl-ammoniuhydroxide as a single structure-directing agent. The hierarchical SAPO-5 reveals high crystallinity, and large external surface areas validated by the XRD and N 2 adsorption-desorption. SEM and TEM indicate that the flowerlike hierarchical SAPO-5 is composed of loosely stacked primary nanorods with average diameter of 20 nm. FT-IR and EDS analyses show that as increasing crystallization time, more and more Si species are incorporated into the AFI crystals. Moreover, it is found that a dynamic crystallization condition is very mandatory toward the synthesis of a novel-flowerlike SAPO-5. [ABSTRACT FROM AUTHOR]