PtFe@S-1 Coupling with ZSM-5 for the Propane Dehydro-Aromatization Reaction: The Effect of Acidity and <i>b</i>-Axis Diffusion Distance

A series of ZSM-5 zeolites with different acidities and b-axis diffusion distances were synthesized under hydrothermal conditions using the seed-induced method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ammonia temperature-programmed desorption (NH3-TPD), and infrared spectroscopic analysis of the adsorption of pyridine (Py-IR). The structure–activity relationships of PtFe@S-1&ZSM-5 tandem catalysts in the propane dehydro-aromatization reaction (PDA) were investigated, especially focusing on the impact of ZSM-5 acidity and b-axis diffusion distance. The results indicate that the ZSM-5 zeolite with a low Si/Al ratio (∼25) and suitable b-axis diffusion distance (∼100 nm) coupled with PtFe@S-1 is more conducive on improving the PDA catalytic performance. When the mass ratio of PtFe@S-1/ZSM-5 was 1:1, the propane conversion and aromatics selectivity of PtFe@S-1&ZSM-5–25 remained above 78.9% and 40.5% within 500 min on stream, respectively.