SAPO-5 molecular sieve with AFI topology has been ionothermally synthesized by microwave irradiation and using eutectic mixture based on pentaerythritol and choline chloride as reaction medium. The resultant SAPO-5 molecular sieve was characterized by X-ray diffraction (XRD), 29Si magic-angle spinning nuclear magnetic resonance (29Si MAS-NMR), N2 physisorption, scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), and thermogravimetry–differential thermal analysis (TG–DTA). 29Si MAS-NMR showed that the incorporation of Si in the calcined sample was mainly by the SM3 mechanism. N2 physisorption measurements confirmed that the resulting SAPO-5 molecular sieve contained mesopores with a pore radius of about 3–30nm. CHN and TG–DTA analysis revealed that it was choline that directed the synthesis of SAPO-5. Moreover, the factors affecting the crystallization of SAPO-5 molecular sieve were investigated in detail. The results showed that P2O5/Al2O3 ratios, HF/Al2O3 ratios and reaction temperature had great impact on the crystallization of SAPO-5.

FeAlPO-5 molecular sieve with AFI topology was ionothermally prepared under microwave irradiation in a three-component eutectic mixture and characterized by various techniques. N2 adsorption/desorption measurements implied that the resultant samples exhibited a mesopore characteristic. Electron spin resonance (ESR) and diffuse reflectance UV–Visible spectra (DR UV–Vis) results revealed that various iron species coexisted on the mesoporous FeAlPO-5 molecular sieve. CHN elemental analysis, thermogravimetry–differential thermal analysis (TG–DTA) and the results of Fourier transform infrared spectra (FT-IR) suggested that tetraethylammonium bromide acted as the structure-directing agent in the synthetic process of FeAlPO-5 molecular sieve. In addition, the factors affecting the crystallization of FeAlPO-5 molecular sieve were investigated in detail. Contrary to the effect of the composition of the eutectic mixture, the types of iron and aluminum sources, as well as the addition of water, did not have major influences on the phase selectivity of the crystallization reaction. Relatively low P2O5/Al2O3 ratio, the addition of appropriate amount of HF, a longer time and higher temperature favored the crystallization of FeAlPO-5 molecular sieve.

FeAlPO-16 molecular sieve with AST topologyhas been ionothermally prepared under microwave irradiationin succinic acid-choline chloride eutectic mixture forthe first time. The structure and morphology of FeAlPO-16molecular sieve are characterized in detail by powder X-Raydiffraction (XRD), Fourier transform infrared spectroscopy(FT-IR), diffuse reflectance UV–visible (UV–vis) spectroscopy,thermogravimetry–differential scanning calorimetryanalysis (TG-DSC) and scanning electron microscopy(SEM). UV–vis results suggest that iron species may partiallyenter the framework of FeAlPO-16 molecular sieve.SEM images indicate that large spherical particles observedin the images are agglomerates of FeAlPO-16 molecularsieve nanocrystalline (ca. 100 nm in size). Effects of synthesisconditions, such as P2O5/Al2O3 ratio, pyridine/Al2O3ratio, reaction temperature and crystallization time, as wellas iron and aluminum source on the crystallization ofFeAlPO-16 molecular sieve are systematically investigated.Experiments show that FeAlPO-16 molecular sieve canbe prepared over a wide molar ratio of Al2O3:xP2O5:yPyridine:0.4Fe2O3:58EU (x = 1.0–3.5, y = 0.8–7.8) usingaluminum isopropoxide and ferric ammonium citrate asiron and aluminum source, respectively. The synthesis ofFeAlPO-16 molecular sieve is highly sensitive to ironsource, but not to aluminum source, crystallization temperatureand time.