n-Pentane Hydroconversion Using Pt-loaded Zeolite Catalysts.

Pt/H-ZSM-5 and Pt/H-MOR catalysts with different Pt contents were prepared via impregnation using H2PtCl6 · 6H2O or via exchange using Pt(NH3)4Cl2, calcination in air at 530°C and reduction in H2 at 500°C. The prepared catalysts were tested for n-pentane hydroisomerization and hydrocracking via bifunctionality at 250-500°C using a micro-catalytic pulse reactor. It is found that the dispersion of Pt-exchanged zeolites is higher than the corresponding Pt-impregnated zeolites at all Pt contents. It is also found that the dispersion of Pt/H-ZSM-5 catalysts either exchanged or impregnated are higher than the corresponding Pt/H-MOR catalysts. Temperature-programmed desorption (TPD) data showed that the impregnated catalysts possess a higher acid sites number than the exchanged catalysts; and that the Pt/H-ZSM-5 catalysts have a higher number of acid sites than do the Pt/H-MOR catalysts, whereas the latter catalysts possess higher strength of acid sites at all Pt contents. The hydroisomerization activities using Pt exchanged catalysts, supported either on H-ZSM-5 or H-MOR, are higher than the impregnated catalysts at almost all Pt contents. It is also concluded that the H-ZSM-5-supported catalysts, either exchanged or impregnated, are more active than the H-MOR supported ones. Hydrocracking is higher using all loaded H-MOR catalysts. [ABSTRACT FROM AUTHOR]