Facile synthesis of FeAlPO-5 molecular sieve in eutectic mixture via a microwave-assisted process

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.

Graphical abstractFeAlPO-5 molecular sieves with AFI topology were ionothermally prepared under microwave irradiation in a three-component eutectic mixture. The synthesized materials exhibit a mesopore characteristic.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► FeAlPO-5 was ionothermally synthesized by microwave irradiation in eutectic mixture. ► The resultant samples had approximate 20 nm mesopore. ► Iron source did not affect the phase selectivity of the crystallization reaction.