Optimization of crystal growth of hierarchical porosity ZSM‐5 zeolite based on coal fly ash “waste utilization”

Abstract 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.