Fabrication of c-axis oriented ZSM-5 hollow fibers based on an in situ solid-solid transformation mechanism.

We report, for the first time, the preparation of novel c-axis oriented ZSM-5 hollow fibers by a combination of seeding and steam-assisted crystallization method using quartz fibers as the temporary soft substrate and Si source. The growth of such unique structure undergoes the development of a b-axis oriented ZSM-5 cylinder, followed by the growth of c-axis oriented ZSM-5 crystals vertically inside the cylinder and then outside the cylinder, by an in situ solid-solid transformation mechanism. The obtained ZSM-5 hollow fibers are composed of pure hierarchical ZSM-5 crystals with high crystallinity, good structural stability, and high surface area and have potential applications for microreactors, separators, and catalysts. The catalytic performance of ZSM-5 hollow fibers is tested in the methanol to gasoline reaction, as an example of their practical application. They exhibit both higher yield of gasoline and far longer lifetime compared to the conventional ZSM-5 due to the improved mass and heat diffusion rate inside the meso-/macropores of c-axis oriented structure.