Active Sites in H-Mordenite Catalysts Probed by NMR and FTIR

Mordenites are widely used in catalysis and environmental protection. The catalytic properties of mordenite largely determined by the composition its crystal framework, i.e., SiO2/Al2O3 molar ratio (MR), cationic form. In H-mordenites, most important characteristic becomes structure distribution acid sites, which depends on number Al tetrahedra framework. present work, local these centers H-mordenite catalysts with a nominal MR varied from 9.9 to 19.8 was studied detail using combination magic angle spinning nuclear magnetic resonance (MAS NMR) Fourier transform infrared spectroscopy (FTIR). 27Al MAS NMR indicates presence extra-framework samples that results higher real zeolitic framework compared value. Concentrations Lewis Brønsted as well silanol groups were estimated elemental analysis, NMR, FTIR spectroscopy. values site concentrations obtained band intensities adsorbed CO those OH amount aluminum. advantages restrictions different methods active characterization discussed.