Ferric nitrate nonahydrate induced synthesis of hollow zeolite with high framework iron content.

It is of great significance to develop a novel strategy to synthesize hollow zeolite without using mesoporogens due to its extremely short diffusion length. Ferric nitrate as a common iron source and structure direction agent has been used for synthesizing Fe-doped zeolite. However, the effect of ferric nitrate on the morphology of zeolite has not yet been elaborated. Here, we successfully synthesized hollow MFI zeolite with a framework iron-rich surface by using ferric nitrate as an iron source and seed-assistant strategy. It is the first time to propose that inorganic iron has the hollow structure-directing effect. Herein, by comparatively investigated the effect of iron content on the structure and evolution process of hollow zeolite, a novel crystallization mechanism has been proposed based on the competitive relationship between crystallization and dissolution rates. When the Si/Fe ratio reaches 25, the internal dissolution rate of seeds is faster than the surface crystallization rate of zeolite, the hollow structures are acquired. The obtained Fe-doped hollow zeolite exhibits superior catalytic performance for the reaction of phenol degradation. In this reaction, the higher effectiveness factor (η) close to 1 of Fe-doped hollow zeolite confirmed by calculations indicates its superior mass transferability. [Display omitted] • Hollow MFI zeolite with Fe-rich surface was synthesized by using Fe(NO 3) 3 and seed. • Ferric nitrate as a direct agent of hollow zeolite has been confirmed. • A mechanism was proved namely competition between crystallization and dissolution. • High content Fe (Si/Fe ratio = 25) is conducive to the formation of hollow zeolite. • Hollow Fe-MFI zeolite shows a superior catalytic activity for phenol degradation. [ABSTRACT FROM AUTHOR]