Ionothermal synthesis of AlPO4 molecular sieves in the presence of quaternary ammonium cation

Several aluminophosphate molecular sieves were synthesized ionothermally, in ionic liquid 1-butyl-3-methyl imidazolium bromide ([BMIm]Br) with adding various quaternary ammonium cation (quats, including tetramethyl ammonium (TMA+), choline, tetraethyl ammonium (TEA+), tetrapropyl ammonium (TPA+) and tetrabutyl ammonium (TBA+)). These products were characterized by X-ray diffraction (XRD), 13C nuclear magnetic resonance (NMR) and scanning electron microscope (SEM). The result indicates that the crystallization pathway is changed by adding these quats. AlPO4-42 (IZA code LTA) crystallizes when TMA+ is added in the system, AlPO4-5 (AFI) crystallizes when choline or TEA+ is added, and the AlPO4-11 (AEL) crystallizes when TPA+ or TBA+ is added. 13C NMR analysis indicates that these introduced quats may either replace the [BMIm]+ to act as template alone, or direct structures cooperatively with the [BMIm]+, or in some cases they cannot change the original structure directing effect of [BMIm]+.