Optimization of crystal growth of hierarchical porosity ZSM-5 zeolite based on coal fly ash “waste utilization”Optimierung des Kristallwachstums hierarchischer Porosität ZSM-5-Zeolith auf Basis von Kohlenflugasche „Müll-Verwendung”

In this study, ZSM-5 zeolite with hierarchical porosity structure was synthesized by hydrothermal method using Al(OH) 3 , SiO 2 extracted from coal fly ash as aluminum source and silicon source. The optimal synthesis parameters of ZSM-5 zeolite were determined via an orthogonal analysis table. The optimum synthesis conditions were: SiO 2 /Al 2 O 3 /Na 2 O/hexadecyltrimethylammonium bromide/tetrapropyl ammonium bromide/H 2 O = 1/0.08/0.25/0.05/0.17/50, and the optimum crystallization temperature and crystallization time were 160 °C and 48 h, respectively. Scanning electron microscopy showed that the synthesized ZSM-5 zeolite exhibited a spherical shape. Nitrogen adsorption-desorption and Brunauer-Emmett-Teller measurement analysis displayed that the best sample ZSM-5 molecular sieve showed a typical type IV isotherm, and the micropores and mesopores coexisted in the sample, indicating the successful preparation of ZSM-5 zeolite with hierarchical porosity structure. The crystal growth of ZSM-5 under different hydrothermal conditions follows the “S” adjustment.