Interfacial nanoarchitectonics for accelerated growth of zeolite via enlarging gel-liquid interfacial area using rotating packed bed.

Typically, silica-alumina zeolites are hydrothermally synthesized in the sodium-rich dense hydrogel systems with a relatively long crystallization time in industry. The fast and economical synthesis of silica-alumina zeolites is still a big challenge. Herein, we develop a universal method to tackle this issue using the rotating packed bed (RPB). An interesting phenomenon is found that gel-liquid interfacial areas in the zeolite precursor are obviously enlarged when RPB is employed, and thus the following crystallization rates of zeolites are greatly improved, especially for the initial nucleation process. Also, we successfully control the growth rates of silica-alumina zeolite by adjusting the gel-liquid interfacial areas. Furthermore, we find that the transfer rate of OH− and hydrated sodium ions from liquid part to gel phase is enhanced by RPB in the initial nucleation process, which greatly promotes the nucleation rate of zeolites. The density functional theory (DFT) calculations demonstrate that hydrated sodium ions can induce the dehydrogenation of Si–OH to generate reactive oxygen radicals, thus lowering the energy barrier of the polymerization reaction and consequently accelerating the nucleation process. Moreover, NaY, NaZSM-5, and NaA zeolites with larger surface areas and more pore volumes are successfully synthesized by this RPB-enhanced-interface strategy, and their crystallization processes are all greatly accelerated. The gel-liquid interfacial areas in the zeolite precursor are obviously enlarged when RPB is employed, which reduces the diffusion resistance of sodium ions from liquid to gel phase in the early period of zeolite nucleation. DFT calculations indicate that sodium ions can induce the dehydrogenation of Si–OH to generate the oxygen free radical, which lowers the energy barrier of zeolite nucleation. Thus, RPB-enhanced-interface strategy can effectively accelerate the nucleation and crystallization process of zeolite. [Display omitted] • Rotating packed bed (RPB) can effectively accelerate the growth process of zeolites. • Zeolites prepared with RPB exhibit relatively large surface areas and pore volumes. • The diffusion resistance of active species in the zeolite synthetic system can be reduced. • Sodium ions promote zeolite nucleation via inducing the generation of oxygen radical. [ABSTRACT FROM AUTHOR]