Pt supported on Zn modified silicalite-1 zeolite as a catalyst for n-hexane aromatization

Platinum (Pt) supported on Zinc (Zn) modified silicalite-1 (S-1) zeolite (denoted as Pt-Zn/S-1) was prepared by using a wetness-impregnation method and applied in the n-hexane aromatization reaction for the first time. Both Lewis and Brønsted acid sites were detected in Pt-Zn/S-1 catalyst by means of FT-IR adsorption of NH3 experiment, which were identified as mostly weak and medium ones. Besides, Pt and Zn species showed strong interaction, as revealed by the TPR (Temperature-programmed reduction) and XPS (X-ray photoelectron spectroscopy) experiments. Pt-Zn/S-1 catalyst exhibited excellent aromatization function rather than isomerization and cracking side reactions in the conversion of n-hexane. Pulse experimental study showed that 75.6% of n-hexane conversion and 76.8% of benzene selectivity were obtained over Pt0.1-Zn6.0/S-1 catalyst at 550 °C and under atmospheric pressure. By spectroscopy tests and pulse experimental results, it was concluded that the n-hexane aromatization over Pt-Zn/S-1 catalyst follows a metal-acid bifunctional mechanism. Furthermore, with the assistance of Zn, the electron-deficient Pt species in Pt-Zn/S-1 showed good sulfur tolerance performance.