Influence of Granulated Hierarchical Zeolite ZSM-5 Physicochemical Properties on Its Catalytic Performance in Skraup Synthesis of Quinolines

This study aimed to investigate the influence of the content of crystalline (10, 30, 60%) and amorphous (90, 70, 40%) aluminosilicates in the starting granules prepared for the synthesis of hierarchical ZSM-5 zeolite on the physicochemical properties, activity, selectivity, and stability of the resulting materials in the Skraup reaction for quinoline synthesis. As the ZSM-5 content in the parent granules was raised from 10 to 60%, increasing trends were observed for the micropore volume (from 0.10 to 0.13 cm³/g) and mesopore volume (from 0.05 to 0.19 cm³/g) in the granules of the resultant hierarchical zeolites H-ZSM-5_h(10, 30, 60). At the same time, the macropore volume decreased from 0.34 to 0.29 cm³/g. The H-ZSM-5_h(60) sample had the highest concentration of acid sites and exhibited the highest activity and selectivity in the Skraup reaction, as evidenced by 72% yield of quinolines. Moreover, this sample exhibited the highest stability, H-ZSM-5_h(60) remained stable for 9 h, whereas the activity of H-ZSM-5_h(10) and H-ZSM-5_h(30) dropped after 3–4 h.