Platelike MFI Crystals with Controlled Crystal Faces Aspect Ratio
Résumé
Zeolite crystals offering a short diffusion pathway through the pore network are highly desired for a number of catalytic and molecule separation applications. Herein, we develop a simple synthetic strategy toward reducing the thickness along b-axis of MFI-type crystals, thus providing a short diffusion path along the straight channel. Our approach combines preliminary aging and a fluoride-assisted low-temperature crystallization. The synthesized MFI crystals are in the micron-size range along a-and c-axis, while the thickness along the b-axis is a few tens of nanometers. The synthesis parameters controlling the formation of plate-like zeolite are studied, and the factors controlling the zeolite growth identified. The synthesis strategy works equally well with all-silica MFI (silicalite-1) and its Al-and Ga-containing derivatives. The catalytic activity of plate-like ZSM-5 in the methanol-to-hydrocarbons (MTH) reaction is compared with a commercial nano-sized ZSM-5 sample, as the plate-like ZSM-5 exhibits a substantially extended lifetime. The synthesis of plate-like MFI crystals is successfully scaled up to a kilogram scale.
Domaines
Chimie
Origine : Fichiers produits par l'(les) auteur(s)