Wheel-like Mordenite Nanoassemblies with Shortened Channel Lengths for Improved Catalytic Performance in Dimethyl Ether Carbonylation

Abstract

To achieve a better catalytic performance, it is of great interest to synthesize nanosized zeolites with reduced internal diffusion limitations. Herein, c-axis shortened wheel-like mordenite nanoassemblies were synthesized. The crystal growth along the [001] direction was successfully inhibited with K + cations as structure breaking agents. The wheel-like crystal is 1.5−2 μm in diameter and 200−300 nm in thickness. The growth of such a unique structure underwent a nonclassical crystallization process including the generation of amorphous worm-like particles and formation of wheel-like crystallites followed by a−b plane oriented growth of the crystals. The obtained MOR wheel-like assemblies possessed larger surface area and external surface area, displayed better mass transfer properties, and exhibited much better catalytic performance than MOR spheroid-like assemblies and conventional bulk MOR zeolite in dimethyl ether (DME) carbonylation reaction, with two and a half times higher the conversion of DME than the bulk MOR, although these samples had identical Si/Al ratios and acid properties. This work provides a simple route to control the zeolite morphology by alkali metal cations and brings forward an effective strategy to prepare zeolite materials with improved catalytic performance.