Enhanced catalytic activity of Pt/H-ZSM-12 via alkaline post-treatment for the hydroisomerization of n-hexane

Bifunctional Pt/H-ZSM-12 catalysts with enhanced inter-mesoporosity were prepared from synthesized ZSM-12 samples by alkaline post-treatments with or without the presence of the template in the zeolite pores, ammonium ion-exchange, and impregnation with Pt(NH3)(4)Cl-2. Different techniques, such as N-2 adsorption-desorption, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), NH3 temperature-programmed desorption (NH3-TPD), and pyridine-adsorption infra-red spectroscopy (Py-IR), were used to characterize the synthesized samples. The prepared Pt/H-ZSM-12 catalysts were evaluated in the hydroisomerization of n-hexane. The results show that the template-containing ZSM-12 is a better parent for introducing abundant inter-mesopores by the alkaline post-treatment, accompanying with a better preservation of microporosity and strong acid sites, in comparison to the template-free ZSM-12 as the parent. In addition, the dispersion of Pt on the alkaline-treated zeolite is increased as well, which is also helpful to enhance the conversion of n-hexane and the selectivity for the dibranched hexanes.