Solvent-free, small organic lactam-assisted synthesis of ZSM-5 zeolites

Abstract

Herein, we report the solvent-free synthesis of ZSM-5 zeolites assisted by the small organic lactam. i.e., N-methyl-2-pyrrolidone (NMP). An array of characterization techniques (XRD, FTIR, and SEM) confirmed the formation of intergrown, highly crystalline ZSM-5 with a size of around 10 μm. To investigate the structure of NMP within the ZSM-5 synthesis, we have performed the 13C liquid NMR spectroscopy measurement, which showed the presence of preserved NMP (cyclic molecule) and a ring-opened NMP molecule. Ultimately, a density functional theory (DFT)-based computational study resulted in the negative formation energies suggested that both molecules could be stabilized within the straight and zig-zag channels of ZSM-5 frameworks. To the best of our knowledge, this is the first time NMP can be utilized as an organic structure-directing agent for crystallizing ZSM-5 zeolites.