Correlating structural variation with catalytic performance of hierarchical zeolites using ultra-high-field solid-state NMR

Ultra-high-field solid-state NMR spectroscopy (1.0 GHz, 23.5 T) was employed to reveal the structural evolution of aluminum species and thus their correlations to catalytic cracking performance of Y zeolites after post-synthetic treatments. Microwave-assisted treatments, including chelating dealumination and NH4OH treatment, induced significant changes in both framework and extra-framework aluminum species. NMR analysis identified that the interaction between extra-framework Al(V/VI) and Bronsted acid sites (BAS) plays a crucial role in enhancing catalytic efficiency. The hierarchical zeolite Y-MWNH3-0.1-30 exhibited superior catalytic cracking performance, achieving high yields of light hydrocarbons (C1–C4) and maintaining excellent selectivity toward BTX during the cracking of bulky molecules. These findings provide new insights into how post-synthetic modifications can be used to tune aluminum species distribution and acid site interaction, optimizing zeolite catalysts for improved performance in hydrocarbon conversion.