Solvent-free synthesis of FeAPO-44 molecular sieves with CHA structures

The FeAPO-44 molecular sieve with CHA-type structure has been synthesized under solvent-free conditions. This is the first case that this material was successfully prepared by this novel solvent-free method. Its optimal synthesis conditions were refined. The results show that proper P2O5/Al2O3 ratio, a lower SDA/Al2O3 ratio (SDA: cyclohexylamine) and relatively mild crystallization temperature are more beneficial to the synthesis of pure CHA phase. The structural and compositional characteristics of the relatively pure FeAPO-44 zeolite were studied in depth by XRD, TG-DSC, CHN element analysis, EDS, SEM and N-2 physisorption. According to the CHN element analysis, EDS and TG-DSC measurements, the approximate chemical formula of the synthesized sample SDA/Al-1.4 was determined. The catalytic performances of selected samples were investigated in the methanol-to-olefins reaction. The present results imply that many other zeolite topologies may be conveniently prepared by this solvent-free route.