One-pot synthesis of nano-hierarchical SSZ-13 with superior catalytic performance in methanol-to-olefins reaction

Nano-sized SSZ-13 with hierarchical structure were fast synthesized by combining ultrasonic pretreatment and seed induced crystallization. The physicochemical properties of the synthesized catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N 2 adsorption–desorption, X-ray fluorescence (XRF), Transmission electron microscopy (TEM), and temperature programmed desorption of ammonia (NH 3 -TPD) analysis. As verified by XRD and SEM, ultrasonic pretreatment not only remarkably reduced the crystallization time to 7 h but also evidently decreased the zeolite crystals to nano size (ca. 650 nm). The N 2 adsorption–desorption and TEM resulted revealed that ultrasonic pretreatment created abundant intracrystalline mesopores in the zeolite structures. In comparison to the conventional SM-24 catalyst, both improved catalytic lifetime and selectivity of ethylene and propylene were obtained over the hierarchical nano-sized SN-17 catalyst due to the greatly enhanced mass transport efficiency and decreased coking rate.