Ultrafast post-synthesis treatment to prepare ZSM-5@Silicalite-1 as a core-shell structured zeolite catalyst

Post-synthesis treatment is an effective way to modify zeolites to acquire desirable properties. Here, we present an ultrafast post-synthesis treatment to prepare core-shell structured zeolite, which is composed of a ZSM-5 core and a silicalite-1 shell. The pure silica shell, which is aimed to remove the Brønsted acid sites associated with the framework Al on the external surface of aluminosilicate core, was formed unprecedentedly within several minutes by our method. Complementary techniques, such as XRD, TG/DTA, SEM, TEM, ICP, and XPS, were employed to verify the successful coverage of the silicalite-1 shell onto the ZSM-5 core. By adjusting the treating period, temperature, and reactant compositions, the thickness of the shell can be easily tuned. Further, this ultrafast process enabled the establishment of a continuous flow reaction system, which could allow the mass production of core-shell structured zeolite catalysts.