Rapid synthesis of hierarchical SSZ-13 zeolite microspheres via a fluoride-assisted in situ growth route using aluminum isopropoxide as aluminum source.

Hierarchical SSZ-13 zeolite microspheres were quickly synthesized by adding a small quantity of hydrofluoric acid in the starting gel using aluminum isopropoxide as aluminum source. The as-synthesized hierarchical SSZ-13 crystals with high crystallinity, pore volume and external surface area were obtained within 12 h, whereas a much longer time (144 h) was necessary to synthesize a fully crystalline zeolite in a fluorine free system. The obtained hierarchical SSZ-13 catalysts showed excellent MTO performance together with considerably prolonged catalytic lifetime and improved selectivity of light olefins in comparison with the conventional microporous SSZ-13.

Template-Free Synthesis of Hierarchical SSZ-13 Microspheres with High MTO Catalytic Activity.

Hierarchical SSZ-13 microspheres, with abundant mesoporous channels, have been successfully synthesized by addition of calcined SSZ-13 crystals in the starting gel in the absence of any organic templates. This strategy not only remarkably reduces the production cost and environmental pollution, but also significantly decreases the crystallization time as well as evidently reducing the zeolite crystal sizes in many cases. The synthesized sample was characterized by XRD, BET, ICP, SEM, TEM, TG, and NH3 -TPD, which indicates that the organic template free synthesized SSZ-13 exhibits high crystallinity, textural properties, and acidity. Moreover, the synthesized hierarchical SSZ-13 catalyst shows outstanding performance in the methanol-to-olefin (MTO) reaction, with slightly higher ethylene plus propylene selectivity and prolonged catalyst lifetime as compared to the templated SSZ-13 catalyst.