Structure-guided control of Al sites in MFI zeolites: Toward rational catalyst design for efficient methane dehydroaromatization

Abstract

This work introduces a rational approach to enhance methane dehydroaromatization (MDA) by precisely tuning the location of aluminum atoms within the MFI zeolite framework. By employing combinations of tetrapropylammonium cation (TPA+), pentaerythritol (PET), and Na+ ions as structure-directing agents (SDAs), Al atoms were selectively positioned at channel intersections, within straight/sinusoidal channels, or across both environments in the MFI framework. Comprehensive analysis of aluminum site distribution was conducted using 27Al MQ MAS NMR, ion-exchange measurements, and ethylene aromatization as a probe reaction. Following Mo impregnation, the dispersion behavior and reduction characteristics of Mo species were elucidated via XPS, H2-TPR, TEM, and XANES.